A Study to Evaluate the Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus (CMV) Vaccine in Healthy Participants 16 to 40 Years of Age

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NCT05085366

Sponsored by ModernaTX, Inc. (industry) · MRNA — their whole pipeline →.

Phase

Phase 3

Status

Terminated

Study type

Interventional

Design

Randomized · Quadruple · Prevention

Enrollment

7,454actual

Sites

296

Countries

Australia, Belgium, Canada +10

Every value on this page is a field the sponsor filed with ClinicalTrials.gov, reproduced. Dates are their own estimates, revised as a study runs, unless the registry marks them actual. sources →

Source: ClinicalTrials.gov, retrieved 2026-08-19

Why the sponsor stopped it

The Sponsor decided to terminate the study after it did not meet the primary efficacy endpoint at final analysis. The safety profile was consistent with prior studies, and no safety concerns were raised by the Data and Safety Monitoring Board.

As filed on the registry record, in the sponsor's own words.

Dates

each axis at the precision it was filed, with the registry's own basis

Date

Filed

Basis

What it is

Start

2021-10-26

actual

When the study began enrolling

Primary completion

2025-11-04

actual

The date the last participant is measured for the primary outcome — the readout window

Study completion

2025-11-04

actual

The whole study's end, after follow-up

First posted

2021-10-20

actual

When this record first appeared on the registry

Results posted

—

When the sponsor posted results to the registry

Record updated

2025-12-15

actual

The sponsor's own last edit to this record — every projection above is as current as this date

What it studies

Condition

Cytomegalovirus Infection

Interventions

Biological: mRNA-1647
Biological: Placebo

Primary outcomes

what the primary-completion date above is the date OF

Seroconversion From a Negative to a Positive Result for Serum Immunoglobulin G (IgG) Against Antigens not Encoded by mRNA-1647

measured Day 197 (28 days after the third injection) up to Day 887 (24 months after the third injection)

Number of Participants With Solicited Adverse Reactions (ARs)

measured Up to 176 days (7 days after each injection)

Number of Participants With Unsolicited Adverse Events (AEs)

measured Up to 197 days (28 days after each injection)

Number of Participants With Medically-Attended Adverse Events (MAAEs)

measured Day 1 through 6 months after the last injection (up to 347 days)

Number of Participants With Adverse Event of Special Interests (AESIs) and Serious Adverse Events (SAEs)

measured Day 1 through Month 30

Geometric Mean Titers (GMTs) of Antigen-Specific Neutralizing Antibody (nAb)

measured Month 30 up to Month 54

Geometric Mean Concentration (GMC) of Binding Antibody

measured Month 30 up to Month 54

Seroconversion From a Negative to a Positive Result for Serum IgG Against Antigens not Encoded by mRNA-1647

measured Month 30 up to Month 54

Number of Participants With Systemic Viral Dissemination

measured Month 30 up to Month 54

Publications

PMID 38190492 — linked by the registry
PMID 37899366 — linked by the registry
PMID 36102707 — linked by the registry

Linked on the registry record. A “linked by the registry” entry is NLM's own automated PubMed match, not a claim by the sponsor that the paper reports this study.

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