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A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older

NCT07282665 · Status: RECRUITING · Phase: PHASE3 · Type: INTERVENTIONAL · Enrollment: 32000

Last updated 2026-04-22

No results posted yet for this study

Summary

The purpose of the study is to learn about how effective, safe, and tolerable the Clostridioides difficile (C. difficile) vaccine is in decreasing the number of C. difficile infections (pCDI) in adults 65 years of age or older.

The participants will receive either the C. difficile vaccine or placebo (saline). A placebo does not contain any active ingredients. The vaccines will be given as a shot into the upper arm muscle.

This study looks at the number of diarrhea (loose stools) events related to a C. difficile infection, so the length of the study can change. If these events happen quickly, the study may finish sooner; if they happen slowly, it could take longer. Sometimes, the study might stop early if the vaccine clearly works or clearly doesn't. Participants will stay in the study until enough events have occurred to answer the main question. On average, each person is expected to take part for up to about three and a half years.

During this time, participants will have 3 planned clinical visits and 3 planned phone visits. After these visits, more scheduled clinic visits will happen every year until the end of study.

Besides the scheduled study visits, if at any time during the study a participant has 3 or more loose stools in 24 hours, they will be asked to save the next one (the fourth or later) and contact the study site. The study site will check to see if it could be a C. difficile infection. This check may happen at the clinic or through a phone or video call.

Conditions

  • Clostridioides Difficile Associated Disease

Interventions

BIOLOGICAL

C.difficile vaccine

C.difficile vaccine given as an intramuscular injection

OTHER

Saline Placebo

0.9% sodium chloride solution given as a intramuscular injection

Sponsors & Collaborators

Principal Investigators

  • Pfizer CT.gov Call Center · Pfizer

Study Design

Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
TRIPLE
Model
PARALLEL

Eligibility

Min Age
65 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2025-12-10
Primary Completion
2028-12-11
Completion
2029-06-07
FDA Drug
Yes

Countries

  • United States
  • Argentina
  • Japan
  • United Kingdom

Study Locations

More Related Trials

Entities

Companies

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT07282665 on ClinicalTrials.gov