Item 1A. Risk Factors.

The following information sets forth risk factors that could cause our actual results to differ materially from those contained in forward-looking statements we have made in this Annual Report on Form 10-K and those we may make from time to time. You should carefully consider the risks described below, in addition to the other information contained in this Annual Report on Form 10-K and our other public filings. Our business, financial condition or results of operations could be harmed by any of these risks. The risks and uncertainties described below are not the only ones we face. Additional risks not presently known to us or other factors not perceived by us to present significant risks to our business at this time also may impair our business operations.

Risks Related to our Financial Position and Capital Needs

Our financial condition raises substantial doubt regarding our ability to continue as a going concern.

Our consolidated financial statements have been prepared assuming that we will continue to operate as a going concern, which contemplates the realization of assets, and the satisfaction of liabilities and commitments in the ordinary course of business. Based on our current operating plans and excluding any contribution from future revenues or external financing, however, we believe that our existing cash and cash equivalents will not be sufficient to fund our operating expenses and capital expenditure requirements for more than one year from the issuance of the consolidated financial statements for the year ended December 31, 2025. As a result, we have determined that there is substantial doubt regarding our ability to continue as a going concern, and our independent registered public accounting firm has included in its audit opinion for the year ended December 31, 2025, an explanatory paragraph about such substantial doubt regarding our ability to continue as a going concern.

The substantial doubt regarding our ability to continue as a going concern may adversely affect our stock price and our ability to raise capital necessary to execute our current operating plans. If we are unable to obtain additional capital, we may not be able to continue our operations on the scope or scale as currently conducted, and that could have a material adverse effect on our business, results of operations, financial condition, and ability to operate as a going concern.

We have incurred significant losses since our inception and are highly dependent on the commercial success of our only authorized product, PEMGARDA, for the foreseeable future, until VYD2311 or any other product candidate is authorized or approved and successfully commercialized, if ever. We may not achieve or maintain profitability.

Since our inception, we have incurred significant losses, and we may continue to incur significant expenses and operating losses for the foreseeable future. Our net losses were $52.5 million and $169.9 million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $954.5 million. Since our inception, we have financed our operations primarily with net proceeds from several public and private offerings of our capital stock. After receiving EUA in March 2024, we have also funded our operations from sales of PEMGARDA, but have no other products authorized or approved for commercialization.

We may continue to incur significant expenses and operating losses. Our net losses may fluctuate significantly from quarter to quarter and year to year. Our expenses could increase substantially as we:

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continue to commercialize PEMGARDA, as well as advance development of our other product candidates, such as VBY329;

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advance the development of VYD2311 and prepare for its potential commercial launch, if approved;

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initiate and conduct clinical trials of our product candidates, including our REVOLUTION clinical program for VYD2311;

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develop product candidates in new indications or patient populations;

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advance our preclinical and discovery programs, such as RSV and measles, including development and screening of additional antibodies;

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seek regulatory authorization or approval for any product candidates that successfully complete clinical trials;

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pursue regulatory authorizations or approvals and coverage and reimbursement for our product candidates, if authorized or approved;

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acquire or in-license other product candidates, intellectual property and/or technologies;

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validate our commercial-scale cGMP manufacturing processes, and manufacture material under cGMP at our contracted manufacturing facilities for clinical trials and potential commercial sales;

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maintain, expand, enforce, defend and protect our intellectual property portfolio;

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comply with regulatory requirements established by the applicable regulatory authorities;

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maintain and expand a sales, marketing and distribution infrastructure to commercialize any product candidates for which we may obtain regulatory authorization or approval;

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hire and retain personnel, including research, clinical, development, manufacturing quality control, quality assurance, regulatory, scientific, and other personnel; and

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incur additional legal, accounting and other expenses in operating as a public company.

Our ability to become and remain profitable is heavily dependent on our ability to develop and commercialize product candidates that generate significant revenue. This will require us to be successful in a range of challenging activities on a timeline that keeps pace with viral evolution, including completing preclinical testing and clinical trials of our product candidates, validating manufacturing processes, obtaining regulatory authorization or approval, and manufacturing, distributing, marketing, and selling any products for which we obtain regulatory authorization or approval, as well as discovering and developing additional product candidates. We will remain highly dependent on the commercial success of our only authorized product, PEMGARDA, for the foreseeable future, until VYD2311 or any other product candidate is authorized or approved and successfully commercialized, if ever.

Because of the numerous risks and uncertainties associated with product candidate development, we are unable to accurately predict the timing or amount of expenses or when, or if, we will be able to achieve profitability. Even if we achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress the value of our company and could impair our ability to raise capital, expand our business, maintain our development efforts, obtain product authorizations or approvals, diversify our offerings or continue our operations. A decline in the value of our company could also cause you to lose all or part of your investment.

We have a limited operating history and limited experience with commercializing products, which may make it difficult for an investor to evaluate the success of our business to date and to assess our future viability.

We are a biopharmaceutical company with a limited operating history. We commenced operations in June 2020, and to date, we have received regulatory authorization for only one product candidate, PEMGARDA, which received an EUA from the FDA in March 2024 for pre-exposure prophylaxis of COVID-19 in certain immunocompromised patients. It is uncertain as to if or when we may be successful in expanding the authorized use of PEMGARDA, if ever. Our operations to date have been largely focused on organizing and staffing, building an intellectual property portfolio, business planning, conducting research and development, regulatory activities, establishing and executing arrangements for third-party manufacturing of our product candidates, commercializing PEMGARDA, and capital raising. Our recent focus has been and will continue to be supporting the commercialization of PEMGARDA, advancing VYD2311 as our next generation mAb candidate for COVID-19, and preparing for the potential commercial launch of VYD2311, if approved. Furthermore, while we continue to advance our BLA-enabling clinical program for VYD2311, it is uncertain as to if or when we may submit such BLA for VYD2311 or an application for regulatory authorization or approval for any other product candidate, and we may not be successful in receiving any such additional regulatory authorization or approval. Consequently, any predictions you make about our future success or viability may not be as accurate as they could be if we had a longer operating or commercial history. In addition, as a business with a limited operating history, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors.

We will require additional funding through a combination of contribution from revenues, equity offerings, government or private-party grants, debt financings or other capital sources, such as collaborations with other companies, strategic alliances or licensing arrangements to support our continuing operations and pursue our growth strategy. If we are unable to secure and access additional funding when needed, we could be forced to curtail our planned operations and the pursuit of our growth strategy.

Our operations have consumed substantial amounts of cash since inception, and, although we received an EUA from the FDA for PEMGARDA in March 2024, we may continue to incur significant expenses and operating losses as we continue to advance VYD2311 as our next generation mAb candidate for COVID-19 and otherwise develop our product candidate pipeline. Aside from any revenue generated from sales of PEMGARDA, additional revenue, if any, will be derived from sales of products that may not be commercially available for a number of years, if at all. Furthermore, even if we obtain regulatory authorization to expand the authorized use of PEMGARDA or if we obtain regulatory approval of VYD2311 or regulatory authorization or approval for another product candidate that we develop or otherwise acquire, we may incur significant commercialization expenses related to product sales, marketing, distribution and manufacturing. Accordingly, until such time, if ever, as we can generate substantial revenue from PEMGARDA or sales of any future authorized or approved product, we expect to finance

our operations through a combination of equity offerings, government or private-party grants, debt financings or other capital sources, such as collaborations with other companies, strategic alliances or licensing arrangements.

As of December 31, 2025, we had cash and cash equivalents of $226.7 million. We plan to use our cash and cash equivalents to fund research and development, manufacturing supply and commercialization costs for our product candidates, the development of additional programs in our pipeline and for working capital and other general corporate purposes. The timing and amount of our funding requirements will depend on many factors, including:

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the revenue received from sales of PEMGARDA and any other product candidates for which we receive future regulatory authorization or approval;

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the rate of progress in the development of our product candidates, such as VYD2311 and VBY329;

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the scope, progress, results and costs of discovery, nonclinical studies, preclinical development, laboratory testing and clinical trials for our product candidates and associated development programs;

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the extent to which we develop, in-license or acquire other product candidates, intellectual property and/or technologies;

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the scope, progress, results and costs of manufacturing and validation activities associated with our current product candidates and with the development and manufacturing of our future product candidates as we advance them through preclinical and clinical development;

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the number and development requirements of product candidates that we may pursue;

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the costs, timing and outcome of regulatory review of our product candidates;

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our headcount growth and associated costs as we expand our research and development capabilities and build and maintain a commercial infrastructure;

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the timing and costs of securing sufficient manufacturing capacity for clinical and commercial supply of our product candidates, or the raw material components thereof;

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the costs and timing of commercialization activities, including product manufacturing, marketing, sales and distribution, for any of our product candidates for which we receive regulatory authorization or approval;

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the costs necessary to obtain regulatory authorizations or approvals, and the costs of post-marketing studies that could be required by regulatory authorities in jurisdictions where authorization or approval is obtained;

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the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims;

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the continuation of our existing licensing and collaboration arrangements and entry into new collaborations and licensing arrangements, if at all;

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the costs we incur in maintaining business operations;

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the need to implement additional internal systems and infrastructure;

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the effect of competing technological, product and market developments;

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the costs of operating as a public company; and

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the impact of any business interruptions to our operations or to those of our third-party contractors resulting from any public health crisis.

We expect to require additional capital to achieve our business objectives. In December 2023, we entered into a Controlled Equity OfferingSM Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co., as sales agent (“Cantor”), pursuant to which we may, at our option, offer and sell shares of our common stock from time to time through Cantor in transactions deemed to be “at the market offerings”, as defined in Rule 415 under the Securities Act of 1933. Funds additional to the proceeds we may raise under the Sales Agreement may not be available on a timely basis, on favorable terms or at all, and such funds, if raised, may not be sufficient to enable us to continue to implement our long-term business strategy. Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our product candidates. Further, our ability to raise additional capital may be adversely impacted by potential worsening global economic conditions, including tariff uncertainty, higher inflation rates, changes in interest rates and the recent disruptions to and volatility in the credit and financial markets in the U.S. and worldwide. If we are

unable to secure additional funding when needed, we could be forced to curtail our planned operations and the pursuit of our growth strategy.

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate substantial revenue from sales of authorized or approved products, such as PEMGARDA, we expect to finance our operations through a combination of equity offerings, government or private-party grants, debt financings or other capital sources, such as collaborations with other companies, strategic alliances or licensing arrangements. Aside from our milestone-based Term Facility (as defined below), we do not currently have any other committed external source of funds. To the extent that we raise additional capital through the sale of equity, including pursuant to our existing Sales Agreement with Cantor, or convertible debt securities, your ownership interest will be diluted, and the terms of such securities may include liquidation or other preferences that adversely affect your rights as a common stockholder. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Such restrictions could adversely impact our ability to conduct our operations and execute our business plan.

If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, we may be required to relinquish valuable rights to our technologies, future revenue streams or product candidates, grant licenses on terms that may not be favorable to us or commit to future payment streams. If we are unable to raise additional funds when needed, we may be required to delay, limit, reduce or terminate our product development or commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Our failure to comply with the covenants or other terms of our Loan Agreement, including as a result of events beyond our control, could result in a default under the Loan Agreement that could materially and adversely affect the ongoing viability of our business.

On April 18, 2025 (the “Closing Date”), we entered into that certain Loan and Security Agreement (the “Loan Agreement”) with Silicon Valley Bank, a division of First-Citizens Bank & Trust Company, as lender (the “Lender”), that provides for a senior secured term loan facility in an aggregate principal amount of up to $30 million (the “Term Facility”) consisting of: (a) Term A Loans in an aggregate principal amount of up to $10 million, which shall be available to be drawn from and after August 15, 2025 through December 31, 2026 upon compliance with certain financial covenants and conditions; (b) Term B Loans in an aggregate principal amount of up to $10 million, which shall be available to be drawn during the period commencing on the date of the achievement of certain net product revenue milestones and ending on June 30, 2027; and (c) Term C Loans in an aggregate principal amount of up to $10 million, which shall be available to be drawn during the period commencing on the date of the achievement of certain net product revenue milestones and ending on June 30, 2027 (collectively, the “Term Loans”).

The Term Loans (i) are due and payable on March 1, 2029 (the “Maturity Date”) and (ii) bear interest that is payable monthly (commencing with the month in which any loans are funded under the Term Facility) in arrears at a per annum rate (subject to increase during an Event of Default (as defined in the Loan Agreement)) equal to the greater of (x) the Wall Street Journal prime rate minus 0.25% (subject to a 9.00% cap) and (y) 6.00%. Commencing on April 1, 2027 (which date may be extended to April 1, 2028 upon the achievement of certain net product revenue milestones (the “Interest-Only Period Extension”)), we will be required to repay the principal of the Term Facility in 24 consecutive equal monthly installments (or, in the case of the Interest-Only Period Extension, 12 consecutive equal monthly installments). At maturity, or if earlier prepaid, we will also be required to pay a final payment fee equal to 4.50% of the aggregate principal amount of the Term Loans advanced under the Term Facility. The Loan Agreement provides for an unused term loan commitment fee equal to 1.00% of the Term Facility upon the earliest to occur of (1) July 1, 2027, (2) the occurrence of an Event of Default and (3) the termination of the Loan Agreement; provided, that such fee will be waived by the Lender in the event that we have requested and the Lender has funded any loans under the Term Facility prior to such date.

Our obligations under the Loan Agreement are secured by a pledge of substantially all of our assets, excluding intellectual property. Certain of our future subsidiaries, if any, will be required to become co-borrowers under the Loan Agreement or guarantee our obligations under the Loan Agreement. In addition, such subsidiaries will be required to pledge substantially all of their assets, excluding intellectual property, to secure our obligations under the Loan Agreement. None of our subsidiaries in existence as of the Closing Date were required to be co-borrowers or guarantors or to so pledge their assets.

The Loan Agreement contains affirmative and negative covenants, including limitations on our ability and our subsidiaries’ abilities, among other things, to incur additional debt, grant or permit additional liens, make investments and acquisitions, merge or consolidate with others, dispose of assets, pay dividends and distributions, enter into affiliate transactions and change our line of business, in each case, subject to certain exceptions. In addition, the Loan Agreement contains quarterly financial covenants requiring us to maintain (a) commencing at the end of the quarter following the advance of any loans under

the Term Facility, a certain amount of minimum net product revenue and (b) commencing with the quarter ending December 31, 2025, either (i) a certain amount of minimum EBITDA or (ii) minimum unrestricted cash and cash equivalents in an amount equal to or greater than the greater of (x) an amount equal to the sum of our six-month Cash Burn (as defined in the Loan Agreement) and the aggregate amount of loans outstanding under the Term Facility and (y) the aggregate amount of loans outstanding under the Term Facility multiplied by two (the “Minimum Cash Threshold”). In addition, if we no longer maintain active sales of a product in the U.S., we will be required to maintain the Minimum Cash Threshold at all times.

The Loan Agreement also includes Events of Default, in certain cases subject to customary periods to cure, following which the Lender may accelerate all amounts outstanding under the Term Facility and stop advancing money or extending credit. For example, the Lender may elect to accelerate the repayment of all unpaid principal of the Term Loans, accrued interest and other amounts owed under the Loan Agreement upon the occurrence of certain Events of Default, including, among other things:

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our default in a payment obligation under the Loan Agreement;

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our breach of the restrictive covenants or other terms of the Loan Agreement;

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the occurrence of a material adverse change in our business operations or condition (financial or otherwise);

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a material impairment in the perfection or priority of the Lender’s lien in the collateral specified in the Loan Agreement;

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certain specified judgment defaults and cross-defaults to other debt agreements;

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the consummation of a specified change of control transaction; and

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certain specified insolvency and bankruptcy-related events.

If we draw down any of the Term Loans under the Term Facility, our assets or cash flow may not be sufficient to fully repay our obligations under the Loan Agreement if the obligations thereunder are accelerated upon any Events of Default. Further, if we are unable to repay, refinance or restructure our obligations under the Loan Agreement, the Lender could proceed to protect and enforce their rights under the Loan Agreement by exercising such remedies (including foreclosure on the assets securing our obligations under the Loan Agreement) as are available to the Lender and in respect thereof under applicable law, either by suit in equity or by action at law, or both, whether for specific performance of any covenant or other agreement contained in the Loan Agreement or in aid of the exercise of any power granted in the Loan Agreement. The foregoing would materially and adversely affect the ongoing viability of our business.

If we are unable to satisfy certain conditions in the Loan Agreement, we will be unable to draw down the amounts of the term loan facility.

For our Loan Agreement, we must satisfy certain conditions to be eligible to draw down the Term Loans.

The Term A Loans shall be available to be drawn from and after August 15, 2025 through December 31, 2026 upon compliance with certain financial covenants, provided that we satisfy certain conditions described in the Loan Agreement. The Term B Loans shall be available to be drawn during the period commencing on the date of the achievement of certain net product revenue milestones and ending on June 30, 2027, provided that we satisfy certain conditions described in the Loan Agreement. The Term C Loans shall be available to be drawn during the period commencing on the date of the achievement of certain net product revenue milestones and ending on June 30, 2027, provided that we satisfy certain conditions described in the Loan Agreement. As of December 31, 2025, we had not satisfied certain financial covenants and conditions, including the net product revenue milestone required to be eligible to access proceeds from the Term Facility. Accordingly, as of December 31, 2025, no amounts have been drawn down under the Loan Agreement.

If we are unable to satisfy those conditions, we would not be able to draw down the respective Term Loans and may not be able to obtain alternative financing on commercially reasonable terms or at all.

Our Loan Agreement contains restrictions that limit our flexibility in operating our business.

The Loan Agreement contains various covenants that limit our ability to engage in specified types of transactions without the prior consent of the Lender, including our ability to, among other things:

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convey, sell, lease, transfer, assign, or otherwise dispose of our assets;

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engage in any business other than the businesses currently engaged in by us or reasonably related thereto;

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liquidate or dissolve;

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merge or consolidate;

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acquire all or substantially all of the stock, partnership, membership, or other ownership interest or other equity securities or property of another entity;

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create, incur or assume additional indebtedness;

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encumber or permit liens on certain of our assets;

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make restricted payments, including paying dividends on, repurchasing or making distributions with respect to our common stock, subject to certain exceptions;

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make specified investments; and

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enter into certain transactions with our affiliates.

The covenants in our Loan Agreement may limit our ability to take certain actions that may be in our long-term best interests. In the event that we breach one or more covenants, the Lender may choose to declare an Event of Default and require that we immediately repay any amounts outstanding under the Loan Agreement, plus fees, terminate the Lender’s commitments to fund any undrawn Term Loans and foreclose on the collateral granted to them to secure the obligations under the Loan Agreement. Such repayment could have a material adverse effect on our business, operating results and financial condition.

To service our indebtedness, as applicable, we will require a significant amount of cash and our ability to generate cash depends on many factors beyond our control.

Our ability to make cash payments on our indebtedness, as applicable, will depend on our ability to generate significant operating cash flow in the future. This ability is, to a significant extent, subject to general economic, financial, competitive, legislative, regulatory and other factors, that will be beyond our control. In addition, our business may not generate sufficient cash flow from operations to enable us to pay our indebtedness or to fund our other liquidity needs. In any such circumstance, we may need to refinance all or a portion of our indebtedness, on or before maturity. We may not be able to refinance any indebtedness on commercially reasonable terms or at all. If we cannot service our indebtedness, as applicable, we may have to take actions such as selling assets, seeking additional equity or reducing or delaying capital expenditures, strategic acquisitions and investments. Any such action, if necessary, may not be effected on commercially reasonable terms or at all. The instruments governing our indebtedness may restrict our ability to sell assets and our use of the proceeds from such sales.

Risks Related to the Development of our Product Candidates

Newly emerging and future SARS-CoV-2 variants could reduce the activity and effectiveness of mAbs for potential prevention of or treatment for symptomatic COVID-19, which may significantly and adversely affect our ability to complete our clinical trials and to obtain and maintain authorization or approval of and commercialize our product candidates.

Our primary focus since inception has been the development of antibodies against COVID-19. Multiple variants of the virus that causes COVID-19 have been documented in the U.S. and globally, and newly emerging and future SARS-CoV-2 variants could reduce the activity and effectiveness of mAbs for potential prevention of or treatment for symptomatic COVID-19, which may significantly and adversely affect our ability to complete our clinical trials and to obtain and maintain authorization or approval of and commercialize our product candidates. For example, although preclinical studies showed that our investigational mAb adintrevimab had the potential to broadly neutralize SARS-CoV-2 and previously predominantly circulating variants, including Alpha, Beta, Delta, and Gamma, in vitro analyses to evaluate neutralizing activity of adintrevimab against the Omicron variant and its sublineages generated data showing reduced neutralizing activity of adintrevimab against the Omicron BA.1 and BA.1.1 sublineages compared to a reference strain and a lack of neutralizing activity against Omicron BA.2. As a result, we paused enrollment in adintrevimab’s Phase 2/3 trials in January 2022, which were subsequently closed, and we paused submission of an EUA request.

PEMGARDA, which received an EUA from the FDA in March 2024, is an engineered version of adintrevimab, which we modified to improve binding to the Omicron variant and its sublineages. PEMGARDA is authorized for use only when the combined national frequency of variants with substantially reduced susceptibility to PEMGARDA is less than or equal to 90%. To date, PEMGARDA has demonstrated in vitro neutralizing activity against major SARS-CoV-2 variants, including JN.1, KP.3.1.1, XEC, LP.8.1 and XFG. However, newly emerging and future SARS-CoV-2 variants could reduce the neutralizing activity and effectiveness of PEMGARDA. If this were to occur, the FDA may revise or revoke the EUA for PEMGARDA, which would adversely affect our commercial prospects, and our ability to generate revenues from PEMGARDA may be limited or lost.

As the SARS-CoV-2 virus evolves over time, we anticipate leveraging our integrated technology platform to periodically introduce new mAb candidates. Our platform is designed to produce new mAb candidates that provide broad in vitro neutralization against past and current VOCs and their sublineages and that exert continuous pharmaceutical activity in the face

of viral evolution. For example, in January 2024, we nominated VYD2311, a mAb optimized for neutralization potency against SARS-CoV-2 lineages such as BA.2.86 and JN.1, as a drug candidate. However, new SARS-CoV-2 variants could be less susceptible to such modifications and their mechanisms of action, or the results shown in preclinical studies may not be replicated in clinical trials. Additionally, it is possible that even if a product candidate showed in vitro neutralizing activity against the predominant SARS-CoV-2 variant at the initiation of a clinical trial, the predominant circulating variant may evolve and neutralizing activity of the candidate become reduced or negligible during the course of a clinical trial or at the time of our planned submission for regulatory authorization or approval. Further, we may not be able to address reductions in neutralization potency with adjustments to the dose or dosing frequency, and our current and future product candidates may not be durable enough to increase the probability of providing a longer period of protection than other antibody solutions or be high-functioning and long-lasting with a high barrier to viral escape. These risks may significantly and adversely affect our ability to complete our clinical trials and obtain and maintain approval of and commercialize VYD2311 or any other product candidates. In addition, if our planned dosing of a product candidate were to be increased in response to reduction in neutralizing activity against dominant circulating SARS-CoV-2 variants or for other reasons, it could impact drug supply and pricing, which could adversely affect our commercial prospects. Even if we obtain authorization or approval, such authorization or approval may be revised or revoked based on changes in circulating variants that reduce the neutralizing activity or effectiveness of our product candidates.

To date, we have received regulatory authorization for only one product candidate, PEMGARDA. If we are unable to successfully develop, receive and maintain an EUA or regulatory approval for and commercialize our product candidates for the indications we seek, or successfully develop any other product candidates, or experience significant delays in doing so, our business will be substantially harmed.

To date, we have received regulatory authorization for only one product candidate, PEMGARDA, which has not been approved, but has been authorized for emergency use by the FDA under an EUA only for pre-exposure prophylaxis of COVID-19 in certain adults and adolescent individuals (12 years of age and older weighing at least 40 kg). We currently have no other products approved or authorized for sale. In January 2024, we nominated VYD2311, a next generation mAb candidate for COVID-19, as a drug candidate, and in October 2025, we announced that the FDA cleared our IND application for VYD2311 and provided feedback to advance our REVOLUTION clinical program, which is our development program for VYD2311 comprising two clinical trials, DECLARATION and LIBERTY. In December 2025, we initiated DECLARATION, and in February 2026, we announced alignment with the FDA on LIBERTY, each as further described in Part I, Item 1 “Business” of this Annual Report on Form 10-K. However, we cannot be certain of the current or future development, regulatory or commercialization timelines of VYD2311. Our ability to generate revenue from VYD2311 or any of our other product candidates will depend heavily on successfully completing development, obtaining regulatory authorization or approval, obtaining manufacturing supply, capacity and expertise, and eventually commercializing such product candidates.

The success of PEMGARDA, VYD2311 or any other product candidates that we develop or otherwise may acquire will depend on many factors, including:

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whether the epitopes targeted by PEMGARDA, VYD2311 or any other COVID-19 mAb candidates remain structurally intact, and whether any such product candidates are able to demonstrate and sustain neutralizing activity against new or emerging SARS-CoV-2 variants or whether such SARS-CoV-2 variants reduce the neutralizing activity and effectiveness of such product candidates;

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the continuing need for therapies for the prevention and treatment of COVID-19, including as a result of the development of COVID-19 into an endemic disease, and the existence of any other available therapies that effectively prevent or treat COVID-19 in the populations targeted by our product candidates;

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the timing and progress of our discovery, nonclinical, and clinical development activities;

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the number and scope of nonclinical and clinical programs we decide to pursue;

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our ability to successfully work with the FDA or other regulatory authorities to establish streamlined development pathways that would allow us to efficiently periodically introduce new mAb candidates targeting SARS-CoV-2, including willingness of regulators to utilize a correlate of protection (surrogate of clinical efficacy) to understand and quantify the relationship between COVID-19 mAbs and estimated clinical protection for related mAbs derived from the same platform without requiring clinical assessment of every individual SARS-CoV-2 variant;

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filing acceptable IND applications with the FDA or comparable foreign applications that allow commencement of our planned clinical trials or future clinical trials for our product candidates;

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our ability to align with the FDA or other regulatory authorities as to the design or implementation of our clinical trials, and our eligibility for expedited regulatory review and approval approaches that we may pursue for our product candidates;

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our ability to align with the FDA or other regulatory authorities on the data required to support the regulatory authorization or approvals that we seek for our product candidates;

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the sufficiency of our financial and other resources to complete the necessary nonclinical studies and clinical trials, manufacture our product candidates and complete associated regulatory activities;

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our ability to establish and maintain agreements for clinical and commercial supply of our product candidates, and to successfully develop, obtain regulatory authorization or approval for, and commercialize our product candidates;

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successful enrollment and timely completion of clinical trials, including our ability to generate positive data from any such clinical trials;

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the costs associated with the discovery and development of any additional product candidates we identify in-house or acquire through collaborations;

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timely receipt of regulatory authorizations or approvals, and the scope and duration of any emergency use authorization received, such as the EUA for PEMGARDA;

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developing and expanding sales, marketing and distribution capabilities and commercializing products, if authorized or approved, whether alone or in collaboration with others;

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our ability to secure and maintain required state licenses for distribution of our products, if authorized or approved, or other distribution disruptions;

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acceptance of the benefits and use of our products, including method of administration, if authorized or approved, by patients, the medical community and third-party payors, for their authorized or approved indications;

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the prevalence and severity of adverse events experienced with our product candidates;

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the availability, perceived advantages, cost, safety and efficacy of alternative therapies for any product candidate that we develop;

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our ability to obtain and maintain third-party coverage and adequate reimbursement for our product candidates, if authorized or approved, and the extent to which patients are willing to pay out-of-pocket for such products, in the absence of such coverage or reimbursement;

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the terms and timing of any collaboration, license or other arrangement, including the terms and timing of any milestone payments thereunder;

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our ability to obtain and maintain patent, trademark and trade secret protection and regulatory exclusivity for our product candidates if approved, and otherwise protecting our rights in our intellectual property portfolio;

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our ability to maintain compliance with regulatory requirements, cGCP, cGLP, and cGMP, and to comply effectively with other rules, regulations and procedures applicable to the development and sale of pharmaceutical products;

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potential significant and changing government regulation, regulatory guidance and requirements and evolving treatment guidelines;

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our ability to maintain a continued acceptable safety, tolerability and efficacy profile of products following any authorization or approval; and

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the impact of any business interruptions to our operations or those of third parties with which we work, including as a result of any public health crisis.

If we are not successful with respect to one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully commercialize PEMGARDA or any other product candidates for which we receive regulatory authorization or approval, which would substantially harm our business. If we do not maintain regulatory authorization for PEMGARDA or receive and maintain regulatory authorization or approval for VYD2311 or any other product candidates we develop or otherwise may acquire, we may not be able to continue our operations.

Because our COVID-19 product candidates represent novel approaches to the prevention and/or treatment of a relatively new disease, there are many uncertainties regarding the development, market acceptance, third-party

reimbursement coverage and commercial potential of our COVID-19 product candidates. We may not be successful in aligning with regulators on an expedited and replicable pathway to SARS-CoV-2 mAb authorization or approval.

COVID-19 is a relatively new disease, and the prevention and treatment of this disease is evolving. Another party may be successful in producing a more efficacious prophylaxis or treatment for COVID-19, which may make it more difficult for us to obtain funding or lead to decreased demand for our product candidates. Other small and large companies may be developing therapies for the prevention and/or treatment of COVID-19, including antibodies, vaccines, antivirals and other products. Some of these are being marketed and others are further along in the development and commercialization process than we are and several of these companies have access to larger pools of capital, including government funding, and broader infrastructure that may make them more successful at developing, manufacturing or commercializing their products for the prevention and/or treatment of COVID-19. The success or failure of other companies, or perceived success or failure, may impact our ability to obtain future funding or to successfully commercialize our product candidates for COVID-19 prevention and/or treatment.

As of the date of this report, no mAb has been approved in the U.S. for prevention (pre- or post-exposure) or treatment of COVID-19. Other than the EUA for PEMGARDA issued by the FDA in March 2024, the FDA previously issued an EUA for tixagevimab/cilgavimab for pre-exposure prophylaxis of COVID-19, in addition to EUAs for casirivimab/imdevimab and bamlanivimab/etesevimab for post-exposure prophylaxis of COVID-19 in certain individuals. In addition, four mAb products, casirivimab/imdevimab, bamlanivimab/etesevimab, sotrovimab, and bebtelovimab received an EUA from the FDA for the treatment of COVID-19 in patients at high risk of disease progression. However, the clinical utility of these products has varied over time due to the emergence of SARS-CoV-2 variants demonstrating partial or full resistance to neutralization and at this time none of these products are authorized for the treatment of COVID-19 and, other than PEMGARDA, none of these products are authorized for prevention of COVID-19 in the U.S., due to loss of activity as new variants emerged.

Because the use of mAbs is a relatively new and expanding area of novel therapeutic interventions, there are many uncertainties related to development, marketing, reimbursement and the commercial potential for our product candidates. For example, the development pathways for our COVID-19 mAb candidates have evolved over time. In pursuing, and eventually obtaining, an EUA for PEMGARDA (pemivibart) in the U.S., we aligned with the FDA on a primary efficacy analysis for our CANOPY Phase 3 pivotal clinical trial that used a correlate of protection (surrogate of clinical efficacy) in an immunobridging approach comparing data obtained in the CANOPY clinical trial to certain historical data from our previous Phase 2/3 clinical trial of adintrevimab for the prevention of COVID-19 (EVADE). Based on FDA feedback, the use of a correlate of protection in an immunobridging approach to a pivotal EUA-directed clinical trial may be a reasonable approach for a new mAb candidate when clinical trial data from a “prototype” mAb is available and the new mAb candidate satisfies certain criteria. With respect to VYD2311, our next-generation mAb candidate for COVID-19, rather than pursuing an EUA in the U.S., we aligned with the FDA on a compact and, therefore, rapid pathway to potential BLA approval. As part of Type C meeting feedback, the FDA advised that a single, randomized, placebo-controlled trial evaluating mAb efficacy in prevention of RT-PCR-confirmed symptomatic COVID-19 disease events could support a BLA submission for VYD2311 for the prevention of COVID-19 in a broad population of Americans, and the FDA subsequently cleared our IND application and provided feedback to advance our REVOLUTION clinical program for VYD2311.

We continue to engage with the FDA with the aim of establishing expedited and replicable pathways for the authorization or approval of SARS-CoV-2 mAbs. We are leveraging and applying our experience with adintrevimab, which demonstrated clinically meaningful results and a robust safety package, and PEMGARDA to new therapeutic candidates, including VYD231. We seek to streamline nonclinical toxicology studies where possible, with the intention of reducing dependence on animal studies, and to leverage data to enable the application of surrogate endpoints in COVID development programs. However, there can be no assurance of the outcome of these discussions. In addition, the FDA or other comparable foreign regulatory authorities may take longer than usual to come to a decision on any request for authorization or approval that we submit and may ultimately determine that there is insufficient data, information or experience with our product candidates to support an authorization or approval decision. For example, in July 2024, we submitted a request to the FDA to expand the existing EUA for PEMGARDA to cover treatment of mild-to-moderate COVID-19 in certain immunocompromised patients, and thereafter we provided the FDA with updates as the SARS-CoV-2 virus evolved and we generated data for new variants as part of our ongoing industrial virology effort. The EUA process in the U.S. does not rely on a statutory timeline such as the timelines embedded into PDUFA-based regulatory actions such as a BLA approval process, and the FDA has discretion with respect to EUAs in making its determination about whether, based on the totality of scientific evidence available, the known and potential benefits of a product candidate outweigh the known and potential risks. In February 2025, the FDA declined our EUA amendment request.

The FDA or other comparable foreign regulatory authorities may also require that we conduct additional post-marketing studies or implement risk management programs, such as REMS, until more experience with our product candidates is obtained. Finally, after increased usage, we may find that our product candidates do not have the intended effect or have unanticipated side effects, potentially jeopardizing initial or continuing regulatory authorization or approval and commercial prospects.

The success of our business depends largely upon our ability to develop and periodically introduce new mAbs that can broadly neutralize SARS-CoV-2. Beyond PEMGARDA, which is currently authorized only for pre-exposure prophylaxis of COVID-19 in certain immunocompromised patients, we may fail to deliver future mAbs that effectively prevent or treat symptomatic COVID-19. Even if we are able to identify and develop such mAbs, such as VYD2311, we cannot ensure that such product candidates will achieve regulatory authorization or approval, or achieve commercial success, even if authorized or approved.

If we uncover any previously unknown risks related to our mAbs, or if we experience unanticipated expenses, problems or delays in developing our product candidates, we may be unable to continuously discover and engineer new mAb candidates that can be leveraged to exert continuous pharmaceutical activity in the face of viral evolution. Further, competitors who are developing products with similar technology may experience problems with their products that could identify problems that would potentially harm our business.

There is no assurance that the approaches offered by our product candidates will gain broad acceptance among healthcare practitioners or patients or that governmental agencies or third-party medical insurers will be willing to provide reimbursement coverage for our product candidates. Since our product candidates represent novel approaches to treating various conditions, it may be difficult, in any event, to accurately estimate the potential revenues from these product candidates. Accordingly, we may spend significant capital trying to obtain regulatory authorization or approval for product candidates that have an uncertain commercial market. The market for any products that we successfully develop will also depend on the product profile, including the route of administration, and cost of the product. If we do not successfully develop and commercialize products based upon our approach or find suitable and economical sources for materials used in the production of our products, we will not become profitable, which would materially and adversely affect the value of our common stock.

Preclinical studies and clinical trials are expensive, time-consuming, difficult to design and implement, and involve an uncertain outcome. Further, we may encounter substantial delays in completing the development of our product candidates. If we are not able to obtain and maintain required regulatory authorizations or approvals, we will not be able to successfully commercialize our product candidates, and our ability to generate product revenue will be adversely affected.

To date, we have received regulatory authorization for only one product candidate, PEMGARDA, which has not been approved, but has been authorized for emergency use by the FDA under an EUA only for pre-exposure prophylaxis of COVID-19 in certain immunocompromised patients. VYD2311 is in Phase 3 clinical development. All of our other product candidates, other than adintrevimab, are in preclinical development and their risk of failure is high. The clinical trials and manufacturing of our product candidates are, and the manufacturing and marketing of our products, if authorized or approved, will be, subject to extensive and rigorous review and regulation by numerous government authorities in the U.S. and in other countries where we may test and market our product candidates. Before obtaining regulatory authorization to commercialize any of our product candidates, we must demonstrate through complex and expensive preclinical testing and clinical trials certain efficacy and safety requirements of the applicable regulatory agencies. For regulatory approval, we must demonstrate that our product candidates are both safe and effective for use in each target indication, typically requiring lengthy, large, well-controlled clinical studies. In particular, because our product candidates are subject to regulation as biological products, we will need to demonstrate that they are safe, pure and potent for use in their target indications. Each product candidate must demonstrate an adequate risk versus benefit profile in its intended patient population and for its intended use.

Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain and depends upon numerous factors, including the substantial discretion of the regulatory authorities. In addition, authorization or approval policies, regulations or the type and amount of clinical data necessary to gain authorization or approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions. We cannot guarantee that any clinical trials will be conducted as planned or completed on schedule, if at all. Failure can occur at any time during the clinical trial process, and we could encounter problems that cause us to abandon or repeat clinical trials. Even if our future clinical trials are completed as planned, we cannot be certain that their results will support the safety and effectiveness of our product candidates for their targeted indications or support continued clinical development of such product candidates. Our current or future clinical trial results may not be successful.

In addition, even if such trials are successfully completed, we cannot guarantee that the FDA or foreign regulatory authorities will interpret the results as we do, and more trials could be required before we submit our product candidates for authorization or approval. Moreover, results acceptable to support authorization or approval in one jurisdiction may be deemed inadequate by another regulatory authority to support authorization or approval in that other jurisdiction. To the extent that the results of our trials are not satisfactory to the FDA or foreign regulatory authorities for support of an authorization or approval, we may be required to expend significant resources, which may not be available to us, to conduct additional preclinical studies

or trials for our product candidates either prior to or post-authorization or approval, or they may object to elements of our clinical development program, requiring their alteration.

Of the large number of products in development, only a small percentage successfully complete the FDA’s or comparable foreign regulatory authorities’ approval or authorization processes and are commercialized. Even if we eventually complete clinical testing and receive authorization for emergency use or approval of a BLA or foreign marketing application for our product candidates, the FDA or the comparable foreign regulatory authorities may grant approval or other marketing authorization contingent on the performance of costly additional clinical trials, including post-market clinical trials. The FDA or the comparable foreign regulatory authorities also may authorize or approve for marketing a product candidate for a more limited indication or patient population than we originally request, and the FDA or comparable foreign regulatory authorities may not approve or authorize the labeling that we believe is necessary or desirable for the successful commercialization of a product candidate. Any delay in obtaining, or inability to obtain, applicable regulatory authorization or approval would delay or prevent commercialization of that product candidate and adversely impact our business and prospects.

We have and may experience delays in beginning or conducting clinical trials or numerous unforeseen events before, during or as a result of clinical trials that could delay or prevent our ability to complete clinical trials, receive regulatory authorization or approval or commercialize our product candidates.

We have and may again in the future experience delays in conducting clinical trials, and we do not know whether our clinical trials will begin on time, need to be redesigned, recruit and enroll patients on time or be completed on schedule, or at all. We may experience numerous unforeseen events before, during or after the conduct of our clinical trials that could delay or prevent our ability to complete such trials or receive regulatory authorization or approval for or commercialize our product candidates, or that could significantly increase the cost of such trials, including:

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inability to generate sufficient preclinical, toxicology or other in vivo or in vitro data to support the initiation of clinical trials;

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delays in sufficiently developing, characterizing or controlling a manufacturing process suitable for advanced clinical trials;

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delays in developing suitable assays for screening patients for eligibility for trials with respect to certain product candidates;

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delays in reaching agreement with the FDA or other regulatory authorities as to the design or implementation of our clinical trials, including the use of a correlate of protection (surrogate of clinical efficacy);

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delays in obtaining regulatory authorization to commence a clinical trial;

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challenges in reaching an agreement on acceptable terms with clinical trial sites or prospective CROs, the terms of which can be subject to extensive negotiation and may vary significantly among different clinical trial sites;

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delays in obtaining IRB approval or Ethics Committees opinions at each trial site;

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challenges in recruiting suitable patients to participate in a clinical trial;

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challenges in having patients complete a clinical trial or return for post-treatment follow-up;

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findings from inspections of clinical trial sites or operations by applicable regulatory authorities, or the imposition of a clinical hold;

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clinical sites, CROs or other third parties deviating from trial protocol or dropping out of a trial, including as a result of changing standards of care or the ineligibility of a site to participate;

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failure to perform in accordance with the applicable regulatory requirements, including the FDA’s regulations and cGCP requirements, or applicable regulatory requirements in other countries;

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addressing patient safety concerns that arise during the course of a trial, including the occurrence of adverse events associated with the product candidate that are viewed to outweigh its potential benefits;

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the evolution of SARS-CoV-2 variants during the course of a clinical trial may adversely impact the neutralizing activity of our product candidates and our ability to complete the trial if the potential benefits are no longer determined to outweigh the potential risks of any such product candidate as a result of reduced neutralizing activity against circulating SARS-CoV-2 variants;

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inability to recruit and/or successfully contract with a sufficient number of clinical trial sites;

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difficulties in manufacturing sufficient quantities of product candidate for use in clinical trials, including as a result of supply chain challenges or otherwise;

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suspensions or terminations by IRBs or Ethics Committees at the institutions where such trials are being conducted, by the independent Data Monitoring Committee for such trial or by the FDA or other regulatory authorities due to a number of factors, including those described above;

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changes in regulatory requirements or guidance, or feedback from regulatory authorities that requires us to modify the design or conduct of our clinical trials;

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clinical trials of our product candidates may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon development programs;

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the number of patients required for clinical trials of our product candidates may be larger than we anticipate, especially if regulatory bodies require the completion of non-inferiority or superiority trials or the sample size needs to be increased based on the outcome rates observed during early trial conduct, enrollment in these clinical trials may be slower than we anticipate, or participants may drop out of these clinical trials at a higher rate than we anticipate;

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enrollment in clinical trials may be impacted by the emergence of variants and rate of infection prevalence in the relevant communities, which can change once a trial is initiated;

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the evolution of SARS-CoV-2 variants during the course of a clinical trial may impact the prevalent variant of infection for patients at one or more sites and adversely impact enrollment potential;

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the screen failure rate for clinical trials of our product candidates may be higher than we anticipate, requiring us to screen larger numbers of patients than originally planned;

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the need or desire to modify a trial protocol;

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unforeseen safety issues;

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emergence of dosing issues;

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lack of effectiveness data during clinical trials, including as a result of lower than anticipated viral attack rates in a study population that may inhibit the clinical trial from producing meaningful, statistically valid results, or require expanding the size of the clinical trial, which may be time-consuming and costly;

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changes in the standard of care of the indication being studied;

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our third-party contractors may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

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we or our investigators might have to suspend or terminate clinical trials of our product candidates for various reasons, including non-compliance with regulatory requirements, a finding that our product candidates have undesirable side effects or other unexpected characteristics, or a finding that the participants are being exposed to unacceptable health risks;

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we conducted our STAMP trial (evaluating adintrevimab for the treatment of COVID-19) at sites outside of the U.S.; in the future, the applicable foreign regulatory authorities may determine that a placebo-controlled trial would expose patients to unacceptable health risks (because alternative effective therapies are or may become available in these regions during the conduct of the trial), which could delay enrollment of a trial and the authorization or approval of our products;

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the cost of clinical trials of our product candidates may be greater than we anticipate, and we may not have funds to cover the costs;

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the supply or quality of our product candidates or other materials necessary to conduct clinical trials of our product candidates may be insufficient or inadequate or may not be able to be procured or distributed as needed;

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regulators may revise the guidance or requirements for authorizing or approving our product candidates, or such guidance or requirements may not be as we anticipate; and

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any future collaborators that conduct clinical trials may face any of the above issues and may conduct clinical trials in ways they view as advantageous to them but that are suboptimal for us.

If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully and timely complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we may:

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incur unplanned costs;

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be delayed or unsuccessful in obtaining authorization or approval for our product candidates;

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obtain authorization or approval for indications or patient populations that are not as broad as intended or desired;

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obtain authorization or approval with labeling that includes significant use or distribution restrictions or safety warnings, including boxed warnings (such as for PEMGARDA) or REMS;

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be subject to additional post-marketing testing requirements;

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be subject to changes in the way the product is administered; or

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have regulatory authorities withdraw or suspend their authorization or approval of the product or impose restrictions on its distribution after obtaining authorization or approval.

We, the FDA, other regulatory authorities outside the U.S. or an IRB or Ethics Committees may suspend a clinical trial at any time for various reasons, including if it appears that the clinical trial is exposing participants to unacceptable health risks, including, for example, because the predominant SARS-CoV-2 variant in the country or clinical trial site is not susceptible to our product candidate, or if the FDA or other regulatory authorities outside the U.S. find deficiencies in our IND or similar application outside the U.S. or the conduct of the trial. If we experience delays in the completion of, or the termination of, any clinical trial of any of our product candidates, the commercial prospects of such product candidate will be harmed, and our ability to generate product revenues from such product candidate will be delayed or rendered impossible. In addition, any delays in completing our clinical trials will increase our costs, slow down our product candidate development and authorization or approval process, and jeopardize our ability to commence product sales and generate revenues.

PEMGARDA has not been approved, but has been authorized for emergency use by the FDA under an EUA. All of our product candidates will require extensive clinical testing before we would be in a position to submit a BLA to the FDA or MAA to the EMA or to other regulatory authorities for regulatory approval. We cannot predict with any certainty if or when we might complete the clinical development for our product candidates and submit a BLA or MAA for regulatory approval of any of our product candidates, if at all, or whether any such BLA or MAA will be approved. We may also seek feedback from the FDA, EMA or other regulatory authorities on our clinical development program, and the FDA, EMA or other regulatory authorities may not provide such feedback on a timely basis, or such feedback may not be favorable, which could further delay our development programs.

We cannot predict with any certainty whether or when we might complete a given clinical trial, including those that are part of our REVOLUTION clinical program for VYD2311. If we experience delays in the commencement or completion of our clinical trials, or if we terminate a clinical trial prior to completion, the commercial prospects of our product candidates could be harmed, and our ability to generate revenues from our product candidates may be delayed or lost. In addition, any delays in our clinical trials could increase our costs, slow down the development and authorization or approval process and jeopardize our ability to commence product sales and generate revenues. Any of these occurrences may harm our business, financial condition and results of operations. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory authorization or approval of our product candidates.

There can be no assurance that the public health emergency in the U.S. declared under Section 564 of the FDCA permitting the FDA to authorize COVID-19 drugs and biologics for emergency use, such as the EUA for PEMGARDA, will continue to be in place for an extended period of time. If the EUA for PEMGARDA is terminated or revoked, we will be unable to sell PEMGARDA and instead would need to pursue traditional regulatory approval processes, which are lengthy, time consuming and inherently unpredictable, and which we may determine not to pursue. If we are not able to maintain regulatory authorization for PEMGARDA, our business will be substantially harmed.

PEMGARDA is our first and only product candidate that has received regulatory authorization. PEMGARDA is not approved, but has been authorized for emergency use by the FDA under an EUA only for pre-exposure prophylaxis of COVID-19 in certain immunocompromised patients. Such EUA authorizes us to market and sell PEMGARDA in the U.S. under certain conditions. The FDA may issue an EUA during a public health emergency declared under the FDCA if the FDA determines that the known and potential benefits of a product outweigh the known and potential risks and if other regulatory criteria are met. On February 4, 2020, the Secretary of HHS determined pursuant to his authority under Section 564 of the FDCA that COVID-19 represented a public health emergency with significant potential to affect national security or the health and security

of U.S. citizens living abroad. Following this determination, on March 27, 2020, the Secretary of HHS declared that circumstances exist justifying the authorization of emergency use of COVID-19 drugs and biologics, subject to the terms of any authorization issued by the FDA. The EUA for PEMGARDA was issued under this declaration. The Secretary of HHS may terminate this EUA declaration at any time. If the Secretary of HHS terminates an EUA declaration under the FDCA, then any EUAs issued based on that declaration will cease to be in effect, and the FDA may no longer issue EUAs for products covered by that declaration. Accordingly, there is no guarantee of the duration for which we will be able to maintain the PEMGARDA EUA. The emergency use of PEMGARDA is only authorized for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of drugs and biological products under Section 564 of the FDCA, unless the declaration is terminated or authorization is revoked sooner.

We may not market any drug product candidates in the U.S. until we receive regulatory authorization with an EUA or approval of a BLA from the FDA, and we cannot market in the European Union until we receive marketing authorization from the European Commission, or other required regulatory authorization or approval in other countries. Other than the EUA for PEMGARDA in the U.S. for pre-exposure prophylaxis of COVID-19 in certain immunocompromised patients, we have not obtained regulatory authorization or approval for any other product candidate, and it is possible that we may never be successful in expanding the authorized use of PEMGARDA or obtain regulatory authorization or approval for any other product candidates in the future, particularly in light of the FDA’s discretion with respect to EUAs in the U.S. in making its determination about whether, based on the totality of scientific evidence available, the known and potential benefits of a product candidate outweigh the known and potential risks.

Although we received an EUA from the FDA for PEMGARDA, there is no guarantee that we will apply for an EUA or similar authorization for any other product candidates or, if we do apply, that we will be able to obtain an EUA or such similar authorization. If an EUA or other authorization is granted, we will rely on the FDA or other applicable regulatory authority policies and guidance governing products authorized in this manner in connection with the marketing and sale of our product. If these policies and guidance change unexpectedly and/or materially or if we misinterpret them, potential sales of our product could be adversely impacted. Additionally, the FDA may terminate an EUA if safety issues or other concerns about our product, such as loss of neutralizing activity against dominant circulating SARS-CoV-2 variants, arise or if we fail to comply with the conditions of authorization.

If an existing EUA, such as the EUA for PEMGARDA, is revised or revoked, we would be unable to sell our product candidate and instead, we would need to pursue traditional regulatory approval processes. The time required to obtain approval or other marketing authorizations by the FDA and comparable foreign authorities is unpredictable, and it typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. In addition, authorization or approval policies, regulations, and the type and amount of clinical data necessary to gain authorization or approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions.

The FDA and other regulatory authorities may also change their policies, issue additional regulations or revise existing regulations, or take other actions, which may prevent or delay authorization or approval of our future products under development on a timely basis. Such policy or regulatory changes could impose additional requirements upon us that could delay our ability to obtain, increase the costs of compliance or restrict our ability to maintain any regulatory authorizations or approvals we may have obtained. Further, evolving or changing plans or priorities at the FDA or other regulatory bodies, including based on regulatory policy changes, such as those at U.S. agencies such as HHS, FDA and the U.S. Centers for Disease Control due to the change in U.S. presidential administration in January 2025, may significantly impact our ability to obtain or maintain an EUA, including our EUA for PEMGARDA.

We may not succeed in obtaining the regulatory approval necessary to sell our product candidates.

We have devoted significant financial resources and business efforts to the development of our product candidates. While PEMGARDA is our first and only product candidate that has received regulatory authorization, we cannot be certain that PEMGARDA, VYD2311 or any of our other product candidates will receive full regulatory approval.

The development of a product candidate and issues relating to its approval and marketing are subject to extensive regulation by the FDA and other regulatory authorities in the U.S. and by comparable regulatory authorities in other countries. Other than pursuant to an EUA, such as the EUA for PEMGARDA, we are not permitted to market our product candidates in the U.S. until we receive approval of a BLA from the FDA. The time required to obtain regulatory approval by the FDA or comparable foreign authorities is unpredictable but typically takes many years following the commencement of clinical trials and depends on numerous factors, including the substantial discretion of the regulatory authorities. In addition, conditions for approval, regulations, standards of care or the type and amount of clinical data necessary to gain approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions. In August 2025, we announced that we received and aligned with advice from the FDA on a compact and, therefore, rapid pathway to potential BLA for mAb candidate VYD2311 for the prevention of COVID-19. In October 2025, we announced the FDA subsequently cleared our IND

application and provided feedback to advance our REVOLUTION clinical program for VYD2311 and, in December 2025, we announced initiation of our DECLARATION pivotal clinical trial. However, we cannot be certain that VYD2311 will receive the BLA that we are pursuing in the U.S.

Prior to obtaining approval pursuant to a traditional regulatory approval process to commercialize any drug product candidate in the U.S. or abroad, we must demonstrate with substantial evidence from well-controlled clinical trials, and to the satisfaction of the FDA or foreign regulatory agencies, that such product candidate is safe, pure and effective for its intended uses. BLA submissions must also include significant information regarding CMC for the product candidate. Results from preclinical studies and clinical trials can be interpreted in different ways. Even if we believe the preclinical or clinical data for our product candidates are promising, such data may not be sufficient to support approval by the FDA and other regulatory authorities. The FDA may also require us to conduct additional preclinical studies or clinical trials for our product candidates either prior to or after approval, or it may object to elements of our clinical development programs.

Our product candidates could fail to receive regulatory approval for many reasons, including the following:

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the FDA or comparable foreign regulatory authorities may disagree with the design or implementation of our clinical trials or with our interpretation of data from preclinical studies or clinical trials;

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we may be unable to demonstrate to the satisfaction of the FDA or comparable foreign regulatory authorities that a product candidate is safe and effective for its proposed indication;

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the results of clinical trials may not meet the level of statistical significance required by the FDA or comparable foreign regulatory authorities for approval;

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we may be unable to demonstrate that a product candidate’s clinical and other benefits outweigh its safety risks;

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we may be unable to collect sufficient data from clinical trials of our product candidates to support the submission and filing of a BLA with the FDA, MAA with the EMA or other submission;

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we may fail bioresearch monitoring, FDA inspection or comparable foreign regulatory authorities’ inspection;

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we may fail an FDA or comparable foreign regulatory authorities’ inspection of our third-party contract manufacturing or testing facilities for which we contract and test clinical and commercial supplies;

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the FDA or comparable foreign regulatory authorities may find our contract manufacturing related activities (e.g., process validation, product characterization, product stability and expiry, and comparability establishment) insufficient for approval; and

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the approval policies or regulations of the FDA or comparable foreign authorities may significantly change in a manner rendering our clinical data insufficient for approval.

Even if a product candidate is approved, the FDA may limit the indication for which the product candidate may be marketed, require extensive warnings on the product labeling, or impose other expensive and time-consuming requirements or restrictions as conditions of approval, such as post-market requirements and commitments to conduct clinical trials or nonclinical testing, additional safety monitoring and reporting obligations, or restrictions on sale and distribution. Regulators in other countries and jurisdictions have their own procedures for approval of product candidates with which we must comply prior to marketing in those countries or jurisdictions.

Obtaining regulatory approval for marketing of a product candidate in one country does not ensure that we will be able to obtain regulatory approval in any other country. In addition, delays in approvals or rejections of marketing applications in the U.S. or other countries may be based upon many factors, including regulatory requests for additional analyses, reports, data, preclinical studies and clinical trials, regulatory questions regarding different interpretations of data and results, changes in regulatory policy during the period of product development and the emergence of new information regarding our product candidates or other products. Also, following approval, regulators may impose new or additional requirements or restrictions, or may withdraw regulatory approval altogether.

Any delay or setback in the regulatory approval or commercialization of any of our product candidates could delay our ability to generate revenue and negatively impact our business, financial condition, results of operations and prospects.

Success in preclinical studies or earlier clinical trials may not be indicative of results in future clinical trials. Our product candidates may not have favorable results in later clinical trials, if any, or receive regulatory authorization or approval.

Success in preclinical testing and early clinical trials does not ensure that later clinical trials will generate the same results or otherwise provide adequate data to demonstrate the efficacy and safety of a product candidate. Preclinical tests and Phase 1 and Phase 2 clinical trials are primarily designed to test safety, to study pharmacokinetics and pharmacodynamics and to

understand the side effects of product candidates at various doses and schedules. Success in preclinical or animal studies and early clinical trials does not ensure that later large-scale clinical trials will be successful, nor does it predict final results. For example, we may be unable to identify suitable animal disease models for our product candidates, which could delay or frustrate our ability to proceed into clinical trials or obtain regulatory authorization or approval. Our product candidates may fail to show the desired safety and efficacy in clinical development despite having progressed through preclinical studies and initial clinical trials.

Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials even after achieving promising results in preclinical testing and earlier-stage clinical trials. Data obtained from preclinical and clinical activities are subject to varying interpretations, which may delay, limit or prevent regulatory authorization or approval. In addition, we may experience regulatory delays or rejections as a result of many factors, including changes in regulatory policy during the period of our product candidate development. Any such delays could negatively impact our business, financial condition, results of operations and prospects.

Interim, top-line, initial and preliminary results from our clinical trials that we announce or publish from time to time may change as more data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publicly disclose interim, top-line, initial or preliminary results from our clinical trials. Interim results from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Preliminary or top-line results also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, interim and preliminary data should be viewed with caution until the final data are available. Differences between interim, top-line, initial or preliminary data and final data could significantly harm our business prospects and may cause the trading price of our common stock to fluctuate significantly. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, any top-line results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results once additional data have been received and fully evaluated.

Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in early-stage development and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, preclinical and other nonclinical findings made while clinical trials were underway or safety or efficacy observations made in preclinical studies and clinical trials, including previously unreported adverse events. Further, others, including regulatory agencies may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular development program, the approvability or commercialization of the particular product candidate or product and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and you or others may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure. Any information we determine not to disclose may ultimately be deemed meaningful by you or others with respect to future decisions, conclusions, views, activities or otherwise regarding a particular product candidate or our business.

If the interim, top-line, initial or preliminary data that we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain authorization or approval for, and commercialize, our product candidates may be harmed, which could significantly harm our business prospects.

Our preclinical studies and clinical trials may fail to demonstrate substantial evidence of the safety and efficacy of our product candidates, or serious adverse or unacceptable side effects may be identified during the development of our product candidates, which could prevent, delay or limit the scope of regulatory authorization or approval of our product candidates, limit their commercialization, increase our costs or necessitate the abandonment or limitation of the development of some of our product candidates.

To obtain the requisite regulatory authorizations or approvals to commercialize our product candidates, we must demonstrate through lengthy, complex and expensive preclinical testing and clinical trials that our product candidates are safe, pure and potent for use in each target indication for obtaining product approval, or meet the clinical or surrogate efficacy and the safety primary endpoints of the pivotal clinical trial(s) for an EUA (in addition to other regulatory requirements) towards obtaining an EUA. These trials are expensive and time consuming, and their outcomes are inherently uncertain. Failures can occur at any time during the development process. Preclinical studies and clinical trials often fail to demonstrate safety or efficacy of the product candidate studied for the target indication, and most product candidates that begin clinical trials are never approved. We may fail to demonstrate with substantial evidence from adequate and well-controlled trials, and to the

satisfaction of the FDA or comparable foreign regulatory authorities, that our product candidates are safe and effective for their intended uses or otherwise meet requirements for an EUA.

If our product candidates are associated with undesirable effects in preclinical studies or clinical trials or have characteristics that are unexpected, we may decide or be required to perform additional preclinical studies or to halt or delay further clinical development of our product candidates or to limit their development to more narrow uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective, which may limit the commercial use for the product candidate, if authorized or approved. Some side effects may not be appropriately recognized or managed by the treating medical staff, such as anaphylaxis that has been seen in the class of mAbs of which PEMGARDA is a part, and toxicities resulting from mAb therapy targeting an exogenous target, as with our product candidates, which can be nonspecific. Anaphylaxis has been observed with PEMGARDA.

If any such adverse events occur, our clinical trials could be suspended or terminated. If we cannot demonstrate that any adverse events were not caused by the drug, the FDA or foreign regulatory authorities could order us to cease further development of, or deny approval of, our product candidates for any or all targeted indications, or require that we conduct additional animal or human studies regarding the safety and efficacy of our product candidates that we have not planned or anticipated. Side effects may also lead regulatory authorities to require stronger product warnings on the product label including boxed warnings or warnings and precautions, costly post-marketing studies, and/or a REMS, among other possible requirements. For example, PEMGARDA has been authorized with a boxed warning for anaphylaxis, which could impede our ability to successfully market and commercialize PEMGARDA and our ability to compete successfully against our competitors.

Such findings could further result in regulatory authorities failing to provide authorization or approval for our product candidates or limiting the scope of the authorized or approved indication, if authorized or approved. Many product candidates that initially showed promise in early-stage testing have later been found to cause side effects that prevented further development of the product candidate. Even if we are able to demonstrate that any serious adverse events are not product-related, such occurrences could affect patient recruitment or the ability of enrolled patients to complete the trial. Moreover, if we elect, or are required, to not initiate, delay, suspend or terminate any future clinical trial of any of our product candidates, the commercial prospects of such product candidates may be harmed and our ability to generate product revenues from any of these product candidates may be delayed or eliminated. Any of these occurrences may harm our ability to develop other product candidates and may harm our business, financial condition and prospects significantly.

Additionally, if one or more of our product candidates receives authorization or approval, and we or others identify undesirable side effects caused by such products, a number of potentially significant negative consequences could result, including:

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regulatory authorities may suspend, withdraw or limit authorizations or approvals of such product, or seek an injunction against its manufacture or distribution;

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regulatory authorities may require additional warnings on the label, such as the boxed warning for PEMGARDA for anaphylaxis;

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we may be required to create a medication guide outlining the risks of such side effects for distribution to patients or other requirements subject to a REMS;

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we may be required to change the way a product is administered or conduct additional trials;

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we could be sued and held liable for harm caused to patients;

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we may decide to remove the product from the market;

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we may not be able to achieve or maintain third-party payor coverage and adequate reimbursement;

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we may be subject to fines, injunctions or civil or criminal penalties; and

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our reputation and physician or patient acceptance of our products may suffer.

There can be no assurance that we will resolve any issues related to any product-related adverse events to the satisfaction of the FDA or foreign regulatory agency in a timely manner or at all. Moreover, any of these events could prevent us from achieving or maintaining market acceptance of the particular product candidate, if authorized or approved, and could significantly harm our business, results of operations and prospects.

Lack of awareness or negative public opinion of mAb therapies and increased regulatory scrutiny of mAb therapies to prevent or treat COVID-19 or other infectious diseases may adversely impact the development or commercial success of our product candidates.

The clinical and commercial success of our mAb therapies will depend in part on public acceptance of the use of mAb therapies to prevent or treat COVID-19 or other infectious diseases. Any adverse public attitudes about the use of mAb therapies may adversely impact our ability to enroll clinical trials or successfully commercialize any of our mAb therapies that are authorized or approved. Moreover, our success will depend upon physicians prescribing, and their patients’ willingness to receive, treatments that involve the use of product candidates we may develop in lieu of, or in addition to, existing treatments with which they are already familiar and for which greater clinical data may be available. Additionally, our success may be impacted by overall evolving dynamics in the commercial market for COVID-19 therapeutics, such as greater seasonality of demand, particularly as COVID-19 has developed into an endemic disease.

More restrictive government regulations or negative public opinion may have a negative effect on our business or financial condition and may delay or impair the development and commercialization of our product candidates or demand for any products that are authorized or approved. Adverse events in our or others’ clinical trials, even if not ultimately attributable to our product candidates, and the resulting publicity could result in increased governmental regulation, unfavorable public perception, potential regulatory delays in the authorization or approval of our product candidates, stricter labeling requirements for those product candidates that are authorized or approved or a decrease in demand for any such product candidates, all of which would have a negative impact on our business and operations.

We may experience delays or difficulties in the enrollment and/or retention of patients in clinical trials, or we may pause, delay or terminate enrollment of our clinical trials, which could in turn delay or prevent our receipt of necessary regulatory authorizations or approvals.

Successful and timely completion of clinical trials will require that we enroll, and maintain the enrollment of, a sufficient number of patients. Patient enrollment, a significant factor in the timing of clinical trials, is affected by many factors, including the size and nature of the patient population and competition for patients eligible for our clinical trials with competitors that may have ongoing clinical trials for product candidates that are under development to treat the same indications as one or more of our product candidates, or approved products for the conditions for which we are developing our product candidates.

Further, we may determine that enrollment in a clinical trial should be paused, delayed or terminated in order to revise trial protocols in light of preliminary data generated by the trial or new data generated in other studies. For example, following our review of data generated in external in vitro analyses examining the neutralizing activity of adintrevimab against the Omicron SARS-CoV-2 BA.1 variant in both authentic and pseudovirus assays, in January 2022 we paused enrollment of new patients in both our EVADE (evaluating adintrevimab for the prevention of COVID-19) and STAMP (evaluating adintrevimab for the treatment of COVID-19) clinical trials to assess dosing strategy and revise our trial protocols in light of the global spread of the Omicron variant and its sublineages; we reported preliminary safety and efficacy data from both trials in March 2022, but as a result of the lack of neutralizing activity against the Omicron BA.2 variant, we paused the submission of an EUA request, and we closed such trials. Trials may also be subject to delays as a result of patient enrollment taking longer than anticipated or patient withdrawal. We may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or foreign regulatory authorities. We cannot predict how successful we will be at enrolling patients in future clinical trials. Patient enrollment is affected by other factors, including:

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the eligibility and exclusion criteria for the trial in question;

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the size of the patient population and process for identifying patients;

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the severity and difficulty of diagnosing the disease under investigation;

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the impact infection prevalence may have on enrollment, as well as the emergence and evolution of SARS-CoV-2 variants, which may impact the prevalent variant of infection for patients at one or more clinical trial sites and adversely impact enrollment potential;

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our ability to recruit clinical trial investigators with the appropriate competencies and experience;

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the design of the trial protocol, including but not limited to the use of a placebo control or active comparator;

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the perceived risks and benefits of the product candidate in the trial, including relating to mAb and/or vaccine approaches;

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the availability of competing commercially available therapies and other competing therapeutic candidates’ clinical trials for the disease or condition under investigation;

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the willingness of patients to be enrolled in our clinical trials;

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the ability to obtain and maintain subject consents;

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the efforts to facilitate timely enrollment in clinical trials;

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potential disruptions caused by a public health crisis, such as the COVID-19 pandemic, including difficulties in initiating clinical sites, enrolling and retaining participants, diversion of healthcare resources away from clinical trials, vaccine mandate policies, travel or quarantine policies that may be implemented, our ability to import and export clinical trial supplies, raw materials and commercial supply and other factors;

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the patient referral practices of physicians;

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the ability to monitor patients adequately during and after treatment;

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the risk that subjects enrolled in our clinical trials will drop out of the trials before completion; and

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the proximity and availability of clinical trial sites for prospective patients.

Our inability to enroll, or maintain the enrollment of, a sufficient number of patients for clinical trials would result in significant delays and could require us to abandon one or more clinical trials altogether. Enrollment pauses or delays in clinical trials may result in increased development costs for our product candidates, which would cause the value of our company to decline and limit our ability to obtain additional financing. Furthermore, we expect to rely on CROs and clinical trial sites to ensure the proper and timely conduct of our clinical trials, and we will have limited influence over their performance.

The accelerated approval pathway, a Fast Track designation or a breakthrough therapy designation in the U.S. or the equivalent thereof in foreign jurisdictions (where available) for any product candidate may not lead to a faster development or regulatory review or approval process, and it does not increase the likelihood that the product candidate will receive full marketing approval.

The FDA has established various expedited drug development programs to facilitate more rapid and efficient development, review and approval of certain types of drugs. Such programs include accelerated approval, Fast Track designation and breakthrough therapy designation. In December 2025, the FDA granted VYD2311 Fast Track designation for the prevention of COVID in individuals with underlying risk factors for severe COVID. The FDA has broad discretion on whether or not to admit a drug candidate for these programs, so even if we believe a particular product candidate is eligible for an expedited drug development program, we cannot be sure that the FDA would agree. Even if any of our product candidates is admitted to any of the expedited drug development programs, such as the Fast Track designation granted for VYD2311,we may not experience a faster development process, review or approval compared to conventional FDA timelines, and the FDA may still ultimately decide to not grant full marketing approval to VYD2311 or any of such other product candidates.

For example, we may pursue accelerated approval or the equivalent thereof in foreign jurisdictions (where available), for our product candidates. The FDA may grant accelerated approval to a product candidate for a serious or life-threatening condition that provides meaningful therapeutic advantage to patients over existing treatments based upon a determination that the product candidate has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit. The FDA may also grant accelerated approval for such a condition when the product candidate has an effect on an intermediate clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality, and that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. As a condition of a grant of accelerated approval, the FDA may require that the sponsor perform one or more controlled post-marketing clinical trials. Accelerated approval of a product candidate may be withdrawn if these trials fails to verify clinical benefit or do not demonstrate sufficient clinical benefit to justify the risks associated with the product candidate (e.g., shows a significantly smaller magnitude or duration of benefit than was anticipated based on the observed effect on the surrogate).

The FDA granted Fast Track designation for VYD2311 in December 2025, and we may pursue Fast Track designation for other product candidates in the U.S., or the equivalent thereof in foreign jurisdictions (where available), which is designed to facilitate the development and expedite the review of therapies for serious conditions that fill an unmet medical need. A product candidate with a Fast Track designation may benefit from early and frequent communications with the FDA, be eligible for priority review and has the ability to submit a rolling application for regulatory review. If any of our product candidates receive Fast Track designation but do not continue to meet the criteria for Fast Track designation, or if our clinical trials are delayed, suspended or terminated, or put on clinical hold due to unexpected adverse events or issues with clinical supply or due to other issues, we will not receive the benefits associated with the Fast Track program. Fast Track designation alone does not guarantee qualification for the FDA’s priority review procedures.

In addition, we may apply for breakthrough therapy designation in the U.S. or the equivalent thereof in foreign jurisdictions (where available), for our product candidates. A breakthrough therapy is defined as a product candidate that is intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the product candidate may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For product candidates that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development. Product candidates designated as breakthrough therapies by the FDA are also eligible for priority review if supported by clinical data at the time of the submission of the BLA.

Granting accelerated approval, Fast Track designation or breakthrough therapy designation is within the discretion of the FDA. Accordingly, even if we determine to pursue a BLA and we believe that one of our product candidates meets the criteria for accelerated approval, Fast Track designation or breakthrough therapy designation, the FDA may disagree and instead determine not to grant such designation. Even if one or more of our product candidates receives conditional approval via the accelerated approval pathway, the FDA may later decide that the product candidate no longer meets the qualifying criteria for such approval, or it may decide that the confirmatory trial(s) failed to verify the clinical benefit or demonstrate sufficient clinical benefit to justify the risks associated with the product candidate, and the FDA may withdraw its conditional approval and/or refuse to grant full approval. Furthermore, the receipt of a Fast Track designation or breakthrough therapy designation for a product candidate may not result in a faster development process, review or full approval compared to product candidates considered for approval under conventional FDA procedures or the traditional FDA approval pathway, and such designations would not assure ultimate approval by the FDA. In addition, even if one or more of our product candidates qualify for Fast Track designation or breakthrough therapy designation, the FDA may later decide that the product candidate no longer meets the conditions for qualification, or it may otherwise not shorten the application review period.

We may expend our limited resources to pursue a particular product candidate or indication and fail to capitalize on product candidates or indications that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial and management resources, we must focus on development programs and product candidates that we identify for specific indications. As such, our current mission is focused on antibody-based therapies that protect vulnerable people from the consequences of viral threats, beginning with SARS-CoV-2, and we have committed a significant portion of our financial and personnel resources to the manufacturing and commercialization of PEMGARDA, which received an EUA from the FDA in March 2024, and the manufacturing and development of VYD2311, our next generation mAb candidate for COVID-19. Our business could be negatively impacted by our allocation of significant resources to a global health threat that is unpredictable and could change, dissipate or stabilize, which could limit or eliminate demand for PEMGARDA, VYD2311 or any new mAb candidates that we anticipate periodically introducing in the future as the SARS-CoV-2 virus evolves over time.

Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future development programs and product candidates for specific indications may not yield any commercially viable products. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

We have conducted and may in the future conduct clinical trials for our product candidates outside the U.S., and the FDA and similar foreign regulatory authorities may not accept data from such trials conducted in locations outside of their jurisdiction.

We have conducted and may in the future conduct clinical trials for our product candidates outside the U.S. The FDA may not accept or may impose additional conditions on trial data from clinical trials conducted outside the U.S. submitted in support of an IND, EUA or BLA. For example, in order for the FDA to accept a foreign clinical trial as support for an IND or application for marketing approval, the FDA requires the following conditions are met: (i) the foreign data are applicable to the U.S. population and U.S. medical practice; (ii) the trial was conducted in accordance with cGCP standards; and (iii) the FDA is able to validate the data from the trial through an onsite inspection if the FDA deems it necessary. Additionally, the FDA’s clinical trial requirements, including sufficient size of patient populations and statistical powering, must be met. Many foreign regulatory bodies have similar approval requirements. In addition, such foreign trials would be subject to the applicable local laws of the foreign jurisdictions where the trials are conducted. There can be no assurance that the FDA or any similar foreign regulatory authority will accept data from trials conducted outside of the U.S. or the applicable jurisdiction. If the FDA or any similar foreign regulatory authority does not accept such data, it would result in the need for additional trials, which would be costly and time-consuming and delay aspects of our business plan, and which may result in our product candidates not receiving approval or authorization for commercialization in the applicable jurisdiction.

We may not be successful in our efforts to build a pipeline of additional product candidates through internal efforts or through partnerships for discovery of novel antibody product candidates.

We may not be able to continue to identify and develop new product candidates in addition to our current pipeline. Even if we are successful in continuing to build our pipeline of antibody therapies for COVID-19 and other serious viral infectious diseases, such as RSV and measles, the potential product candidates that we identify may not be suitable for clinical development. For example, product candidates may be shown to have harmful side effects or other characteristics that indicate that they are unlikely to be successfully developed, much less receive authorization or approval and achieve market acceptance. Further, even if we obtain authorization or approval for a product candidate for one indication that may have potential for new or additional indications, we may determine that those additional indications are not worth pursuing for strategic reasons, including new legislation that may impact our ability to commercialize such compounds for such indications, if authorized or approved. If we do not successfully develop and commercialize product candidates based upon our approach, we will not be able to obtain product revenue in future periods, which would result in significant harm to our financial position and adversely affect our stock price.

Our business and operations may be adversely affected by public health outbreaks, pandemics or epidemics, such as the COVID-19 pandemic.

COVID-19, the disease caused by SARS-CoV-2 and its variants, gave rise to a global pandemic in 2020, and continues to present public health and economic challenges around the world. The evolution and impact of the disease and the continued emergence of VoCs, and the availability, administration and acceptance of vaccines, mAbs, antiviral agents and other therapies may affect the design and enrollment of our clinical trials, the potential regulatory authorization or approval of our product candidates and the commercialization of our product candidates, if authorized or approved.

In addition, our business and operations may be more broadly adversely affected by public health outbreaks, pandemics or epidemics, such as the COVID-19 pandemic, which pose the risk that we or our third-party contractors may be prevented from conducting normal business activities or operations due to spread of the disease, or due to restrictions that may be requested or mandated by federal, state or local governmental authorities.

We experienced some delays in our development activities as a result of the COVID-19 pandemic. For example, in December 2020, shipment of adintrevimab clinical supply by WuXi Biologics was delayed due to the introduction by the Chinese government of a new procedure for the approval of the export of products for the treatment of COVID-19. There could be other disruptions, delays or uncertainties in our development activities as a result of any future public health outbreak, pandemic or epidemic.

Public health outbreaks, pandemics or epidemics, such as the COVID-19 pandemic, which caused a broad impact globally, may also materially affect us economically. For example, a widespread outbreak, pandemic or epidemic could result in significant disruption of global financial markets, reducing our ability to access capital, which could in the future negatively affect our liquidity.

In addition, to the extent that any public health outbreaks, pandemics or epidemics, such as the COVID-19 pandemic, adversely affects our business, financial condition and results of operations, it may also have the effect of heightening many of the other risks and uncertainties described in this “Risk Factors” section.

Our product candidates may be negatively impacted by future development or regulatory difficulties.

Authorized and approved drug products are subject to ongoing regulatory requirements and oversight, including requirements related to manufacturing, quality control, further development, labeling, packaging, storage, distribution, safety surveillance, import, export, advertising, promotion, recordkeeping and reporting. In addition, we are subject to continued compliance with cGMP and cGCP requirements for any clinical trials that we conduct post-authorization or approval. If we or any of the third parties on which we rely fail to meet those requirements, the FDA or comparable regulatory authorities outside the U.S. could initiate enforcement action. Other potential consequences include the issuance of fines, warning letters, untitled letters or holds on clinical trials, product seizure or detention or refusal to permit the import or export of our product candidates, permanent injunctions and consent decrees, or the imposition of civil or criminal penalties, any of which could significantly impair our ability to successfully commercialize a given product. If the FDA or a comparable regulatory authority outside the U.S. becomes aware of new safety information, it can impose additional restrictions on how the product is marketed or may seek to withdraw marketing authorization or approval altogether.

Risks Related to the Manufacturing of our Product Candidates

Monoclonal antibody therapies are complex, difficult and time-consuming to manufacture, and we currently rely on a single contract manufacturer for our COVID-19 product candidates. We could experience manufacturing problems, may be unable to access desired future manufacturing capacity within desired timeframes, or may be unable to access raw

materials due to global supply chain shortages or otherwise, that result in delays in the development, supply, or commercialization of our product candidates or otherwise harm our business.

The manufacture of mAbs and other protein-based therapies are technically complex and necessitate substantial expertise and capital investment. Production difficulties caused by unforeseen events may delay the availability of material for our clinical trials or commercialization efforts.

We rely on WuXi Biologics, a CDMO, for the development and manufacture of our COVID-19 product candidates for clinical and commercial use. Manufacturers of pharmaceutical products must comply with strictly enforced cGMP requirements, state and federal regulations, as well as foreign requirements when applicable. Any failure of us or our CDMO to adhere to or document compliance to such regulatory requirements could lead to a delay or interruption in the availability of product for clinical trials or commercial use, or enforcement action from the FDA or foreign or state regulatory authorities. If we or our CDMO were to fail to comply with the FDA or foreign or state regulatory authorities, it could result in sanctions being imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of authorizations or approvals, license revocation, seizures or recalls of product candidates or products, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our product candidates. Our dependence upon others for the manufacture of our product candidates may also adversely affect our future profit margins, if any, and our ability to commercialize any product candidates that receive regulatory authorization or approval on a timely and competitive basis.

Biological products are inherently difficult and time-consuming to manufacture. Our program materials are manufactured and tested using technically complex processes and/or methods requiring specialized equipment and facilities and other production constraints, including a number of highly specific raw materials, cell lines and reagents with limited suppliers. Even though we aim to have backup supplies of raw materials, cell lines and reagents whenever possible, we cannot be certain they will be sufficient if our primary sources are unavailable. A shortage of a critical raw material, cell line or reagent, or a technical issue during development, manufacturing or testing, may lead to an inability to manufacture our product candidate, resulting in delays in clinical development or commercialization plans. Any changes in the manufacturing of components of the raw materials we use for manufacturing or testing of our product candidates could result in unanticipated or unfavorable effects in our manufacturing processes or product quality or timelines, resulting in delays.

Given the complex, difficult and time-consuming nature of manufacturing our product candidates, we must devote significant resources to the manufacture of our product candidates for clinical and potential commercial supply prior to receiving regulatory authorization or approval, and we may not realize a return on our investment in such supply if a product candidate is not ultimately authorized or approved. For example, we built supply of adintrevimab in anticipation of seeking regulatory authorization, but based on feedback from the FDA regarding adintrevimab’s lack of neutralizing activity against the Omicron BA.2 variant, we paused the submission of an EUA request. More recently, we have incurred substantial costs in building supply of VYD2311, which is currently in Phase 3 development, and we cannot be certain as to if or when we will receive regulatory approval for such product candidate. Even if we ultimately receive regulatory authorization or approval to commercialize a product candidate, such as the EUA for PEMGARDA, if sales do not meet the expected forecasts or a portion of our inventory becomes expired, it may be necessary to write down or write off such obsolete inventory, which could adversely affect our operating results.

While we believe that we have secured sufficient supply to meet demand for PEMGARDA and anticipated initial demand for VYD2311, if approved, any delay, failure or inability to manufacture or test on a timely basis in the future could impact the timelines for our future clinical trials or our commercialization plans. Such delay, failure or inability to manufacture or test can result from:

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a failure in the manufacturing process itself, for example by an error in manufacturing process, operator or human error, equipment failure, raw material or reagent failure, failure in any step of the manufacturing process, failure to maintain a cGMP environment or failure in quality systems applicable to manufacture (whether by us or our third-party contract development and manufacturing organization), sterility failures, testing failure or contamination during processing;

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a lack of reliability or reproducibility in the manufacturing process itself leading to variability in process execution or in product quality, which may lead to regulatory authorities placing a hold on a clinical trial or commercial supply and distribution or requesting further information on the process, which could in turn result in delays to the clinical trials or commercial supply and distributions;

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inability to obtain manufacturing or testing slots within desired timeframes or to have enough manufacturing slots to manufacture our product candidates to meet clinical or commercial requirements and demands;

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unfavorable FDA or foreign or state regulatory inspection of the manufacturing or testing site;

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inability to procure raw materials and reagents due to global supply chain shortages or otherwise;

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loss, depletion or performance degradation of the cell line starting material; and

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loss of or close-down of any manufacturing facility used in the manufacture of our product candidates, or the inability to find alternative manufacturing capability in a timely fashion.

Our product candidates are biologics, and the manufacture of our product candidates is complex and subject to extensive regulations. If we or our third-party contractors fail to comply with such regulations, regulatory authorities may impose sanctions or require remedial measures that could be costly or time-consuming, and our ability to provide supply of our product candidates for clinical trials or commercialization could be delayed or stopped.

All entities involved in the preparation of therapeutics for clinical trials or commercialization, including our existing contract manufacturer and testing facilities, labeling, packaging and storage facilities, and distributors, are subject to extensive regulation. Components of a finished therapeutic product authorized or approved for commercialization or used in clinical trials must be manufactured, tested, and stored in accordance with cGMP. These regulations govern manufacturing processes and procedures (including record keeping) and the implementation and operation of quality systems to control and ensure the quality of investigational products and products authorized or approved for sale. Poor control of production processes can lead to the introduction of adventitious agents or other contaminants, or to inadvertent changes in the properties or stability of our product candidates that may not be detectable in final product testing. We or our contract manufacturer must supply all necessary documentation in support of regulatory authorization or approval on a timely basis. Our facilities and quality systems and the facilities and quality systems of some or all of our third-party contractors will likely need to pass a pre-approval inspection (and may need to pass a pre-authorization inspection) for compliance with the applicable regulations as a condition of regulatory approval (or authorization) of our product candidates. In addition, regulatory authorities may, at any time, audit or inspect us or any of our contract manufacturing, testing, and storage facilities involved with the preparation of our product candidates or our other potential products or the associated quality systems for compliance with the regulations applicable to the activities being conducted, and they could put a hold on one or more of our clinical trials (or could delay regulatory authorization or approval) if the facilities or quality systems of our or third-party contractors do not pass such audit or inspections. Certain of our third-party contractors’ facilities have not yet been inspected by regulatory authorities. If any of our third-party contractors’ facilities do not pass a pre-approval, pre-authorization, or other facility inspection, regulatory approval or authorization of the products may not be granted.

The regulatory authorities also may, at any time following authorization or approval of a product for sale, inspect or audit us or our third-party contractors. If any such inspection or audit identifies a failure to comply with applicable regulations or if compliance discrepancies with our product specifications or violations of applicable regulations occur independent of such an inspection or audit, we or the relevant regulatory authority may require remedial measures that may be costly and/or time-consuming for us or a third party to implement and that may include the temporary or permanent suspension of a clinical trial or commercial sales or the temporary or permanent closure of a facility. Any such remedial measures imposed upon us or third parties with whom we contract could harm our business. If we or any of our third-party contractors fail to maintain regulatory compliance, the FDA or other regulatory authorities can impose regulatory sanctions, including, among other things, refusal to authorize or approve a pending application or to issue a positive opinion for a new drug product, or revocation of a pre-existing authorization or approval. As a result, our business, financial condition and results of operations may be harmed. Additionally, if supply from an approved manufacturer is interrupted, there could be a significant disruption in commercial supply of any authorized or approved products. An alternative manufacturer would need to be qualified and approved, which could result in further delay. The regulatory agencies may also require additional studies if a new manufacturer is relied upon for commercial production. Switching manufacturers may involve substantial costs and is likely to result in a delay in our desired commercial timelines.

These factors could cause the delay of clinical trials, regulatory submissions, required approvals or commercialization of our product candidates, cause us to incur higher costs and prevent us from commercializing our products successfully, if authorized or approved, or could delay commercial supply once authorized or approved. Furthermore, if our third-party contractors fail to meet contractual requirements, and we are unable to secure one or more replacement contractors capable of production at a substantially equivalent cost, our clinical trials or commercialization efforts may be delayed or we could lose potential revenue.

We currently depend on sole-source third-party suppliers and a single contract manufacturer for materials and services that are necessary for the conduct of preclinical studies, manufacture and testing of our COVID-19 product candidates for clinical trials and commercial supply, and the loss of these third-party suppliers or contract manufacturer or their inability to supply us with sufficient quantities of adequate materials or services, or to do so at acceptable quality levels, acceptable pricing terms, and on a timely basis, could harm our business.

Manufacturing and testing our product candidates and commercialization of any authorized or approved products requires many specialty materials and equipment, some of which are manufactured or supplied by small companies with limited

resources and experience to support commercial biologics production. We currently depend on a limited number of vendors for certain materials and equipment used in the manufacture and testing of our product candidates. For example, we are reliant on WuXi Biologics, our current CDMO, as the procurer of the raw materials used in the manufacture of our COVID-19 product candidates, including certain single-source purification resins and cell culture media, which increases the risk of delays in production.

Our current CDMO’s or potential future CDMOs’ raw material suppliers may not have the capacity to support clinical and commercial products manufactured under cGMP by biopharmaceutical firms or may otherwise be ill-equipped to support our needs. We also do not have supply contracts with many of these suppliers directly, and we, our current CDMO or potential future CDMOs may not be able to obtain supply contracts with them on acceptable terms or at all. Accordingly, we, our current CDMO or potential future CDMOs may experience delays in receiving key raw materials and equipment to support clinical or commercial manufacturing.

For some of these specialty materials, we, our current CDMO or potential future CDMOs rely on and may in the future rely on sole-source suppliers or a limited number of suppliers. The supply of specialty materials and equipment that are necessary to produce our product candidates could be reduced or interrupted at any time. In such case, identifying and engaging an alternative supplier could result in delay, and we may not be able to find other acceptable suppliers on acceptable terms, or at all. Switching our suppliers may involve substantial costs and is likely to result in a delay in our desired clinical and commercial timelines. If our key suppliers are lost, or if the supply of the materials is diminished or discontinued, we may not be able to develop, test, manufacture and market our product candidates in a timely and competitive manner, or at all. An inability to continue to source product from any of these suppliers, which could be due to a number of issues, including regulatory actions or requirements affecting the supplier, adverse financial or other strategic developments experienced by a supplier, labor disputes or shortages, unexpected demands or quality issues, could adversely affect our ability to satisfy demand for our product candidates, which could adversely and materially affect our product sales and operating results or our ability to conduct clinical trials, either of which could significantly harm our business.

In addition, to date, we have relied on WuXi Biologics as our only CDMO for our COVID-19 product candidates. We have partnered with WuXi Biologics for CMC development and for clinical and commercial drug substance and drug product supply. While we believe that we have secured sufficient supply to meet demand for PEMGARDA and anticipated initial demand for VYD2311, if approved, the loss of this CDMO, a disruption in production at this CDMO or the inability of this CDMO to timely manufacture sufficient quantities on acceptable pricing terms to meet our needs, and our failure to find alternative manufacturing capability in a timely fashion, would impair our ability to develop and commercialize our product candidates. Although we believe there are other potential alternative CDMOs, the number of CDMOs with the necessary manufacturing and regulatory expertise and facilities to manufacture biologics like our mAb candidates is limited, and switching manufacturers or manufacturing sites would be expensive, difficult and time consuming. A new manufacturer or manufacturing site would have to be educated on, or develop substantially equivalent processes for, production of our product candidates, and it may be difficult or impossible to transfer certain elements of our manufacturing process to a new manufacturer or for us to find a replacement manufacturer on acceptable terms quickly, or at all. Furthermore, switching manufacturers or manufacturing sites may hinder our ability to leverage our platform approach to facilitate the generation of mAbs to exert continuous pharmaceutical activity in the face of viral evolution, which we expect will require a consistent CMC platform. Transferring manufacturing to a new manufacturer or manufacturing site could therefore interrupt supply, delay our clinical trials and commercialization efforts, increase our costs for our product candidates and disrupt our plans to use any potential streamlined development pathway that requires a consistent CMC platform, any of which could have an adverse effect on our business, financial condition, results of operations, and/or growth prospects.

Any contamination or interruption in our manufacturing process, shortages of raw materials or failure of our suppliers of reagents to deliver necessary components could result in delays in our clinical development or commercialization schedules.

Given the nature of mAb manufacturing, there is a risk of contamination, including in the manufacture of raw materials and in the manufacturing of our product candidates, or in the manufacturing or testing facility itself. Any contamination could adversely affect our ability to supply product candidates on schedule and could, therefore, harm our results of operations and cause reputational damage. Some of the raw materials required in our manufacturing process are derived from biologic sources. Such raw materials are difficult to procure and may be subject to contamination or recall. A material shortage, contamination, recall or restriction on the use of biologically derived substances in the manufacture or testing of our product candidates could adversely impact or disrupt the supply of commercial or clinical material, which could adversely affect our development timelines and our business, financial condition, results of operations and prospects.

Changes in methods of product candidate manufacturing or formulation may result in additional costs or delay.

As product candidates proceed through preclinical studies to late-stage clinical trials towards potential approval and commercialization, it is common that various aspects of the development program, such as manufacturing methods and

formulation, are altered along the way in an effort to optimize processes and product characteristics. Such changes carry the risk that they will not achieve our intended objectives. Any such changes could cause our product candidates to perform differently or impact product stability and expiry and affect the results of planned clinical trials or other future clinical trials conducted with the materials manufactured using altered processes or could impact our planned development or commercialization schedule. Such changes may also require additional testing, FDA notification or FDA approval (and similar notifications and approvals by other comparable foreign regulatory authorities). This could delay completion of clinical trials, require the conduct of bridging clinical trials or the repetition of one or more clinical trials, increase clinical trial costs, delay approval of our product candidates and jeopardize our ability to commence sales and generate revenue.

Risks Related to the Commercialization of Our Product Candidates

If the FDA revokes or terminates our EUA for PEMGARDA, we will be required to stop commercial distribution of PEMGARDA immediately unless we can obtain FDA approval for PEMGARDA under a traditional regulatory pathway, which may be lengthy and expensive, which could harm our future business prospects.

Under the FDCA, the FDA has authority to allow certain unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions when there are no adequate, approved, and available alternatives. In issuing an EUA, the FDA will consider the totality of scientific evidence available to the FDA regarding safety, efficacy, and known and potential risks of such products and availability of alternatives to the emergency use products, among others. EUAs issued by the FDA specify the scope of authorization and conditions of authorization, including limitations on distribution and conditions related to product advertising and promotion. Once granted, an EUA is effective until the declaration permitting emergency use authorization is terminated or the EUA is revoked, after which the product must be approved by the FDA under a traditional pathway in order to remain on the market or to continue commercialization of the product in the U.S.

On March 22, 2024, we received an EUA from the FDA for PEMGARDA for the pre-exposure prophylaxis (prevention) of COVID-19 in adults and adolescents (12 years of age and older weighing at least 40 kg) who have moderate-to-severe immune compromise due to certain medical conditions or receipt of certain immunosuppressive medications or treatments and are unlikely to mount an adequate immune response to COVID-19 vaccination. Recipients should not be currently infected with or have had a known recent exposure to an individual infected with SARS-CoV-2.

The distribution and advertising conditions set forth in our EUA limit our market opportunities and restrict how we can commercialize PEMGARDA. For example, according to our EUA, among other requirements, all descriptive printed matter, advertising, and promotional materials relating to the emergency use of PEMGARDA under the EUA must be consistent with the authorized labeling and other terms set forth in the EUA and such materials must be tailored to the intended audience, not take the form of reminder advertisements or reminder labeling, and be accompanied by authorized labeling under certain circumstances. In addition, according to our EUA, printed matter, advertising, and promotional materials relating to the emergency use of PEMGARDA must provide accurate descriptions of safety results and efficacy results on a clinical endpoint(s) or surrogate endpoint(s) from the clinical trial(s) summarized in the authorized labeling, including any limitations of the clinical trial data as described in the authorized labeling, and contain certain clear and conspicuous statements regarding the emergency use authorization. In addition, the PEMGARDA Fact Sheet for Healthcare Providers (“HCPs”) includes a boxed warning for anaphylaxis. If the FDA’s policies and guidance change unexpectedly and/or materially or if we misinterpret them, potential sales of PEMGARDA could be adversely impacted.

In addition, the FDA would be required to revoke our existing or any future EUA if HHS determines that emergency use is no longer warranted. The FDA may also revoke our existing or any future EUA if new evidence becomes available that indicates that PEMGARDA is not as safe, effective, or reliable as the data provided in the EUA request. For example, the FDA may revise or revoke the EUA for PEMGARDA based on changes in circulating SARS-CoV-2 variants and a reduction in neutralizing activity or effectiveness of PEMGARDA against such variants. PEMGARDA is authorized for use only when the combined national frequency of variants with substantially reduced susceptibility to PEMGARDA is less than or equal to 90%. We cannot predict how long our EUA will remain effective, and we may not receive advance notice from the FDA regarding revocation of our EUA. The termination or revocation of our existing EUA for PEMGARDA would cause us to cease our commercialization efforts until and if we have obtained approval from the FDA through another regulatory pathway and would adversely impact our business, financial condition and results of operations.

Additionally, changes in FDA policies, guidance, and requirements for the submission of an EUA request may delay authorization of any additional emergency uses for PEMGARDA. Further, given the high volume of EUA requests received by the FDA, the FDA’s review of an amended or additional EUA request may be significantly delayed. The FDA may not grant an EUA for additional emergency uses of PEMGARDA on a timely basis or at all, which could harm our future business prospects. For example, in July 2024, we submitted a request to the FDA to expand the existing EUA for PEMGARDA to

cover treatment of mild-to-moderate COVID-19 in certain immunocompromised patients, which request was denied by the FDA in February 2025.

Our product candidates may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success, due to the product profile, reimbursement dynamics or other reasons.

If any of our product candidates receive authorization or approval, such as PEMGARDA, which received an EUA from the FDA in March 2024, they may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors and others in the medical community, due to the product profile, reimbursement dynamics or other reasons. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant revenue and we may not become profitable. The degree of market acceptance of our product candidates, if authorized or approved for sale, including PEMGARDA, will depend on a number of factors, including:

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the efficacy, safety and potential advantages compared to alternative treatments, including oral, intramuscular (IM) and intravenous (IV) options;

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our ability to offer our products for sale at competitive prices;

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the convenience and ease of administration, including compared to any alternative treatments;

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product labeling or product insert requirements of the FDA or other foreign regulatory authorities, including any limitations or warnings contained in a product’s approved labeling, including any boxed warning (such as the boxed warning for anaphylaxis for PEMGARDA) or REMS;

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whether we are required by the FDA or other regulatory authorities to conduct additional clinical trials or to modify the design of our current trials to support the initial or continued authorization or approval of a product candidate;

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the willingness of the target patient population to try new treatments and of physicians to prescribe these treatments;

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our ability to maintain and expand our sales force in the U.S.;

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the strength of marketing and distribution support;

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the availability of third-party coverage and adequate reimbursement for any product candidates, once authorized or approved;

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the prevalence and severity of any side effects, such as anaphylaxis for which PEMGARDA received a boxed warning;

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any restrictions on the use of our products together with other medications or requirements that our products be used in combination with other products; and

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the ability to be effective against emerging SARS-CoV-2 variants.

The commercial success of our product candidates, if authorized or approved, is dependent upon market acceptance by physicians, HCPs and patients, which will be informed, in part, by cost, convenience, route of administration, safety and efficacy, including efficacy against emerging SARS-CoV-2 variants over time.

If we are unable to continue to build and maintain sales, marketing and distribution capabilities for PEMGARDA or any other product candidate that may receive regulatory authorization or approval, we may not be successful in commercializing PEMGARDA or such other product candidates if and when they are authorized or approved.

We began commercializing PEMGARDA after we received an EUA from the FDA in March 2024. As a result, we have limited experience marketing our product candidates. Our financial condition and results of operations are and will continue to be highly dependent on the ability of our marketing function to adequately promote PEMGARDA, or any other product candidate that receives regulatory authorization or approval, for appropriate patients in a manner that complies with applicable laws and regulations.

We will need to continue to build and maintain a commercial infrastructure to support the marketing and distribution of PEMGARDA and any other product candidates that may be authorized or approved in the future. To support the commercialization of PEMGARDA, we initially directly hired key leaders for our sales, marketing, market access, and medical affairs teams, and leveraged contract organizations for certain field-based roles. We subsequently determined to invest in direct hire resources, including an internal sales force.

There are risks involved with both establishing our own commercialization capabilities and with entering into arrangements with contract organizations. To the extent that we rely on third parties to perform sales, marketing or distribution services, we likely will have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our products effectively. On the other hand, there are risks involved with establishing our commercial infrastructure. For example, establishing and training our own commercial team is expensive and time consuming.

Factors that may inhibit our efforts to continue to build and maintain our commercialization capabilities include:

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our inability to recruit, train and retain adequate numbers of effective sales and marketing personnel;

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the inability of sales personnel to obtain access to physicians in order to educate physicians about our product candidates, once authorized or approved;

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the lack of complementary products to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive product lines; and

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unforeseen costs and expenses associated with creating independent sales, marketing and market access organizations.

If we do not establish sales, marketing and distribution capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.

A key element of our business strategy is the continued expansion of our marketing infrastructure and building brand awareness. As we continue to increase our marketing efforts in connection with the expansion of PEMGARDA sales, we will need to further expand the reach of our marketing networks. Our future success will depend largely on our ability to continue to hire, train, retain and motivate a skilled marketing workforce, directly or through contract organizations, with significant industry-specific knowledge in various areas, including healthcare, prophylactic treatments, complex biologics, and applicable laws and regulations.

If we are unable to expand our marketing capabilities, we may not be able to effectively commercialize PEMGARDA. Relatedly, if any of our marketing platforms significantly increase their advertising fees, our ability to expand our marketing reach will be greatly impeded. Any such failure could adversely affect our reputation, revenue, and results of operations.

The affected populations for our product candidates, including PEMGARDA, may be smaller than we or third parties currently project, which may affect the addressable markets for our product candidates.

Our mission is to deliver antibody-based therapies that protect vulnerable people from the consequences of viral threats, beginning with COVID-19. In considering the market potential for our product candidates, our projections of the number of immunocompromised people in the U.S. who may not adequately respond to COVID-19 vaccination and the estimated U.S. total addressable market for our mAb candidates for the pre-exposure prophylaxis of COVID-19 are estimates based on Invivyd-sponsored market research and our internal analysis. The number of immunocompromised people in the U.S. who may not adequately respond to COVID-19 vaccination and the estimated U.S. total addressable market for our mAb candidates for the pre-exposure prophylaxis of COVID-19 may turn out to be lower than expected, and patients may not be amenable to our product candidates or may become increasingly difficult to identify and access, all of which would adversely affect our financial condition, results of operations and prospects. Further, even if we obtain authorization or approval for our product candidates, the FDA or other regulators may limit their authorized or approved indications to more narrow uses or subpopulations within the populations for which we are targeting development of our product candidates.

A decline, or a widespread perception of a decline, in the spread or severity of COVID-19, including disease due to variants with relative or absolute resistance to other products, or an increase in available alternative therapies for or widespread immunity to COVID-19, could reduce the total addressable market for our product candidates targeting COVID-19. Similarly, if new SARS-CoV-2 variants are less impacted by our product candidates and their mechanism of action than expected and such variants become more prevalent, the number of patients that we will be able to successfully treat with our product candidates, if authorized or approved, such as PEMGARDA, will be decreased.

The total addressable market opportunity for our product candidates, including PEMGARDA, will ultimately depend upon a number of factors, including the diagnosis and treatment criteria included on the final label, if authorized or approved for sale in specified indications, acceptance by the medical community, patient access, and product pricing and reimbursement. Incidence and prevalence estimates are frequently based on information and assumptions that are not exact and may not be appropriate, and the methodology is forward-looking and speculative. The process we have used in developing an estimated total addressable market has involved using a third party to model the number of people at high risk for severe COVID-19 based on a combination of different data sets, such as the incidence and prevalence of different medical conditions based on primary literature, the portion of patients who are receiving immunosuppressants based on claims data, and interviews/surveys with health care professionals. Accordingly, these estimates included in this filing may turn out to be inaccurate. Further, the

data and statistical information used in this Annual Report on Form 10-K, and in our other filings with the SEC, including estimates derived from them, may differ from information and estimates made by our competitors or from current or future studies conducted by independent sources.

Any revenue we are able to generate from product sales will be dependent, in part, upon the size of the market in the U.S. (and any other jurisdiction for which we may in the future obtain an EUA or similar authorization or obtain regulatory approval and have commercial rights) and our ability to meet the market demand. If the markets or patient subsets that we are targeting are not as significant as we estimate, or if we do not have sufficient supply to meet the market demand, we may not generate significant revenues from sales of such products, even if authorized or approved.

Our commercial prospects may be harmed if academic or other third-party labs not related to us generate virologic activity data that creates doubt regarding the neutralization activity of pemivibart or any other of our product candidates, even if such data is ultimately shown to be inconsistent with neutralization data generated through our industrial-grade virology efforts.

From time to time, academic or other third-party labs not related to us may produce and run tests on their own molecules meant to resemble our molecules, such as pemivibart, or may run tests on our molecules utilizing differing assays and put neutralization findings of unknown quality into the public domain. In connection with the EUA for PEMGARDA, the FDA has acknowledged that neutralization findings from sources other than our independent, contracted vendor may differ due to, among other reasons, assay differences or because the molecule tested by other labs differs from pemivibart in sequence. Nevertheless, publicly available neutralization data against emerging SARS-CoV-2 variants are reviewed by the FDA and may be factored into the totality of evidence when considering the potential for adequate neutralization activity of PEMGARDA to support continued emergency use authorization.

IVVD US Equity

IVVD · 10-K · period ended 2025-12-31

Item 1A. Risk Factors.

IVVD US Equity☆

IVVD · 10-K · period ended 2025-12-31

Item 1A. Risk Factors.

IVVD US Equity