A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
← catalyst calendarNCT07282665 · readout in 845 d
Sponsored by Pfizer (industry) · PFE — their whole pipeline →.
Phase
Phase 3
Status
Recruiting
Study type
Interventional
Design
Randomized · Quadruple · Prevention
Enrollment
32,500estimated
Sites
183
Countries
Argentina, Japan, United Kingdom +1
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
Dates
each axis at the precision it was filed, with the registry's own basis| Date | Filed | Basis | What it is |
|---|---|---|---|
| Start | 2025-12-10 | actual | When the study began enrolling |
| Primary completion | 2028-12-11 | estimated | The date the last participant is measured for the primary outcome — the readout window |
| Study completion | 2029-06-07 | estimated | The whole study's end, after follow-up |
| First posted | 2025-12-15 | actual | When this record first appeared on the registry |
| Results posted | — | When the sponsor posted results to the registry | |
| Record updated | 2026-08-14 | actual | The sponsor's own last edit to this record — every projection above is as current as this date |
What it studies
Condition
- Clostridoides Difficile Associated Disease
Interventions
- Biological: C.difficile vaccine
- Other: Saline Placebo
Primary outcomes
what the primary-completion date above is the date OFThe percentage of participants reporting local reactions
measured For 7 days after each vaccination
The percentage of participants reporting systemic events
measured For 7 days after each vaccination
Percentage of participants reporting adverse events
measured From each vaccination through 1 month after each vaccination
Percentage of participants reporting serious adverse events
measured From Vaccination 1 (Day 1) through 12 months after Vaccination 2 (last dose) (18 months)
The incidence of the first episode of medically attended and clinically meaningful primary Clostridioides difficile infection (CDI)
measured from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
The incidence of the first episode of medically attended primary CDI
measured from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
The incidence of the first episode of clinically meaningful primary CDI
measured from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
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