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

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.

Shortened from the sponsor's brief summary. View official record on ClinicalTrials.gov

Conditions studied

• Clostridoides Difficile Associated Disease

Eligibility basics and study details

Study type

Interventional

Phase

Phase 3

Ages

65 years and older

Sex

All

Healthy volunteers

Accepted

Sponsor

Pfizer

Last updated on ClinicalTrials.gov

October 13, 2026

These are the basic criteria only. The full inclusion and exclusion criteria are on the official record, and the study team decides who can take part.

US recruiting sites