Recruiting

Phase 3

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

Sponsor:

Pfizer

Code:

NCT07282665

Conditions

Clostridoides Difficile Associated Disease

Eligibility Criteria

Sex: All

Age: 65+

Healthy Volunteers: Accepted

Interventions

C.difficile vaccine

Saline Placebo

Study Details

Brief 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 does not work. 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 clinic 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

Clostridoides Difficile Associated Disease

Study ID

NCT07282665

Start date

Dec 10, 2025

Status verified date

Aug, 2026

Completion date

Jun 7, 2029

Anticipated

Primary completion date

Dec 11, 2028

Anticipated

Eligibility Criteria

Sex: All

Age: 65+

Healthy Volunteers: Accepted

Who Can Join the Study (Inclusion Criteria):

• People with recent or future planned contact with healthcare systems, recent antibiotic exposure, or a diagnosis of certain chronic medical conditions.

Who Cannot Join the Study (Exclusion Criteria):

Anyone who has had CDI before.
Anyone who has had surgery to remove part of their small or large intestine.
Anyone who often has diarrhea (meaning three or more loose stools in a day, more than once a month).
Anyone who has already received a vaccine or special antibody treatment for C. difficile.
Anyone who has had a serious allergic reaction to a vaccine or to any part of the study vaccines.
Anyone who might not respond well to the vaccine because their immune system is weak (either from a disease or from treatment).
Anyone with cancer that has spread or another serious health problem.

Study Design

Enrollment

32500 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: C.difficile vaccine

Novel vaccine formulation

other: Saline Placebo

Interventions

C.difficile vaccine

C.difficile vaccine given as an intramuscular injection

Saline Placebo

0.9% sodium chloride solution given as a intramuscular injection

Primary outcome measure

The percentage of participants reporting local reactions [ Time Frame: For 7 days after each vaccination ]
The percentage of participants reporting systemic events [ Time Frame: For 7 days after each vaccination ]
Percentage of participants reporting adverse events [ Time Frame: From each vaccination through 1 month after each vaccination ]
Percentage of participants reporting serious adverse events [ Time Frame: 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) [ Time Frame: 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 [ Time Frame: 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 [ Time Frame: from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years) ]

Central Contacts and Locations

Central contacts

Pfizer CT.gov Call Center

1-800-718-1021 ClinicalTrials.gov_Inquiries@pfizer.com

Locations

North Alabama Research Center

Recruiting

Athens, Alabama, United States, 35611

Lakeview Clinical Research

Recruiting

Guntersville, Alabama, United States, 35976

Medical Affiliated Research Center

Recruiting

Huntsville, Alabama, United States, 35801

Chinle Center for Indigenous Health

Recruiting

Chinle, Arizona, United States, 86503

Chinle Comprehensive Health Care Facility

Recruiting

Chinle, Arizona, United States, 86503

Epic Medical Research-Sun City

Recruiting

Sun City, Arizona, United States, 85351

Applied Research Center of Arkansas

Recruiting

Little Rock, Arkansas, United States, 72205

Kaiser Permanente Daly City

Recruiting

Daly City, California, United States, 94015

Kaiser Permanente Los Angeles Medical Center

Recruiting

Los Angeles, California, United States, 90027

Kaiser Permanente Oncology Pharmacy #014C

Recruiting

Los Angeles, California, United States, 90027

Sacramento VA Medical Center

Recruiting

Mather, California, United States, 95655

Kaiser Permanente Oakland

Recruiting

Oakland, California, United States, 94611

Kaiser Permanente Ontario Medical Center

Recruiting

Ontario, California, United States, 91761

Kaiser Permanente Roseville

Recruiting

Roseville, California, United States, 95661

Kaiser Permanente Sacramento

Recruiting

Sacramento, California, United States, 95815

Kaiser Permanente South Sacramento

Recruiting

Sacramento, California, United States, 95823

Velocity Clinical Research, San Bernardino

Recruiting

San Bernardino, California, United States, 92408

Kaiser Permanente - San Diego Medical Center

Recruiting

San Diego, California, United States, 92123

Kaiser Permanente Viewridge Medical Office

Recruiting

San Diego, California, United States, 92123

Kaiser Permanente San Jose

Recruiting

San Jose, California, United States, 95119

Kaiser Permanente Santa Clara

Recruiting

Santa Clara, California, United States, 95051

Med Partners, Inc. dba Premiere Medical Center of Burbank, Inc.

Recruiting

Toluca Lake, California, United States, 91602

Kaiser Permanente Walnut Creek

Recruiting

Walnut Creek, California, United States, 94596

Diablo Clinical Research, Inc.

Recruiting

Walnut Creek, California, United States, 94598

GW Vaccine Research Unit

Recruiting

Washington D.C., District of Columbia, United States, 20037

The GW Medical Faculty Associates

Recruiting

Washington D.C., District of Columbia, United States, 20037

Bay Pines VA Healthcare System

Recruiting

Bay Pines, Florida, United States, 33744

Proactive Clinical Research,LLC

Recruiting

Fort Lauderdale, Florida, United States, 33308

Clinical Neuroscience Solutions, Inc. dba CNS Healthcare

Recruiting

Jacksonville, Florida, United States, 32256

M3 Wake Research - Lake City

Recruiting

Lake City, Florida, United States, 32055

South Florida Research Organization

Recruiting

Medley, Florida, United States, 33166

Care Research Inc

Recruiting

Miami, Florida, United States, 33130

Entrust Clinical Research

Recruiting

Miami, Florida, United States, 33176

Charisma Medical and Research Center

Recruiting

Miami Lakes, Florida, United States, 33014

Palm Springs Community Health Center

Recruiting

Miami Lakes, Florida, United States, 33014

Indago Research & Health Center, Inc

Recruiting

Miami Lakes, Florida, United States, 33016

Angels Clinical Research Institute

Recruiting

Tampa, Florida, United States, 33614

Emory Steiner Building Research Center

Recruiting

Atlanta, Georgia, United States, 30303

Emory University Woodruff Extension Building (WEB)

Recruiting

Atlanta, Georgia, United States, 30303

Centricity Research Columbus Georgia Multispecialty

Recruiting

Columbus, Georgia, United States, 31904

The Hope Clinic of Emory University

Recruiting

Decatur, Georgia, United States, 30030

Atlanta VA Medical Center

Recruiting

Decatur, Georgia, United States, 30033

Velocity Clinical Research, Savannah

Recruiting

Savannah, Georgia, United States, 31406

DM Clinical Research - Chicago

Recruiting

Melrose Park, Illinois, United States, 60160

Accellacare - McFarland

Recruiting

Ames, Iowa, United States, 50010

McFarland Clinic, PC

Recruiting

Ames, Iowa, United States, 50010

Velocity Clinical Research, Sioux City

Recruiting

Sioux City, Iowa, United States, 51106

AMR Clinical

Recruiting

Newton, Kansas, United States, 67114

Ochsner Medical Complex - The Grove

Recruiting

Baton Rouge, Louisiana, United States, 70836

Ochsner Clinic Foundation - Kenner Clinical Trials Unit

Recruiting

Kenner, Louisiana, United States, 70065

Ochsner Lafayette General Medical Center

Recruiting

Lafayette, Louisiana, United States, 70503

Johns Hopkins Bloomberg School of Public Health

Recruiting

Baltimore, Maryland, United States, 21205

Johns Hopkins Bloomberg School of Public Health

Recruiting

Baltimore, Maryland, United States, 21231

VA Boston Healthcare System - West Roxbury

Recruiting

West Roxbury, Massachusetts, United States, 02132

Revive Research Institute, Inc.

Recruiting

Southfield, Michigan, United States, 48075

DM Clinical Research - Detroit

Recruiting

Southfield, Michigan, United States, 48076

Washington University School of Medicine

Recruiting

St Louis, Missouri, United States, 63110

Sundance Clinical Research

Recruiting

St Louis, Missouri, United States, 63141

Velocity Clinical Research, Grand Island

Recruiting

Grand Island, Nebraska, United States, 68803

University of Nebraska Medical Center

Recruiting

Omaha, Nebraska, United States, 68105

Velocity Clinical Research, Omaha

Recruiting

Omaha, Nebraska, United States, 68134

University Of Nebraska Medical Center

Recruiting

Omaha, Nebraska, United States, 68198

Renown Center for Advanced Medicine

Recruiting

Reno, Nevada, United States, 89502

Renown Regional Medical Center

Recruiting

Reno, Nevada, United States, 89502

University Health

Recruiting

Reno, Nevada, United States, 89519

Hackensack Meridian Health Hackensack University Medical Center

Recruiting

Hackensack, New Jersey, United States, 07601

HMH David Jurist Research Building

Recruiting

Hackensack, New Jersey, United States, 07601

HMH Hackensack University Medical Center

Recruiting

Hackensack, New Jersey, United States, 07601

Hackensack Meridian Health Jersey Shore University Medical Center

Recruiting

Neptune City, New Jersey, United States, 07753

HOPE Tower at Jersey Shore University Medical Center

Recruiting

Neptune City, New Jersey, United States, 07753

Rutgers Robert Wood Johnson Medical School

Recruiting

New Brunswick, New Jersey, United States, 08901

South Jersey Infectious Disease

Recruiting

Somers Point, New Jersey, United States, 08244

Albuquerque Clinical Trials, Inc.

Recruiting

Albuquerque, New Mexico, United States, 87102

Gallup Center for Indigenous Health

Recruiting

Gallup, New Mexico, United States, 87301

Gallup Indian Medical Center

Recruiting

Gallup, New Mexico, United States, 87301

Northern Navajo Medical Center

Recruiting

Shiprock, New Mexico, United States, 87420

Shiprock Center for Indigenous Health

Recruiting

Shiprock, New Mexico, United States, 87420

NYU Langone Health

Recruiting

Brooklyn, New York, United States, 11220

Upstate Global Health Institute

Recruiting

East Syracuse, New York, United States, 13057

Mount Sinai Queens

Recruiting

Long Island City, New York, United States, 11102

North Shore University Hospital

Recruiting

Manhasset, New York, United States, 11030

Northwell Health Infectious Disease

Recruiting

Manhasset, New York, United States, 11030

NYU Langone Health

Recruiting

Mineola, New York, United States, 11501

Northern Westchester Hospital

Recruiting

Mount Kisco, New York, United States, 10549

NYU Langone Health

Recruiting

New York, New York, United States, 10016

Mount Sinai West

Recruiting

New York, New York, United States, 10019

Mount Sinai Morningside

Recruiting

New York, New York, United States, 10025

Icahn School of Medicine at Mount Sinai

Recruiting

New York, New York, United States, 10029

Columbia University Irving Medical Center

Recruiting

New York, New York, United States, 10032

Rochester Clinical Research, LLC

Recruiting

Rochester, New York, United States, 14609

Phelps Hospital Geriatric Medicine & Improvement Science

Recruiting

Sleepy Hollow, New York, United States, 10591

Staten Island University Hospital

Recruiting

Staten Island, New York, United States, 10305

Montefiore Medical Center

Recruiting

The Bronx, New York, United States, 10467

James J. Peters VA Medical Center

Recruiting

The Bronx, New York, United States, 10468

Accellacare - Cary

Recruiting

Cary, North Carolina, United States, 27518

Duke Vaccine and Trials Unit

Recruiting

Durham, North Carolina, United States, 27703

Medication Management

Recruiting

Greensboro, North Carolina, United States, 27405

Accellacare - Hickory

Recruiting

Hickory, North Carolina, United States, 28601

Atrium Health Wake Forest Baptist Infectious Disease-High Point

Recruiting

High Point, North Carolina, United States, 27262

Accellacare - Raleigh

Recruiting

Raleigh, North Carolina, United States, 27609

Duke University Health System

Recruiting

Raleigh, North Carolina, United States, 27609

Raleigh Medical Group P.A.

Recruiting

Raleigh, North Carolina, United States, 27609

Accellacare - Salisbury

Recruiting

Salisbury, North Carolina, United States, 28144

Accellacare - Wilmington

Recruiting

Wilmington, North Carolina, United States, 28401

Wilmington Health, PLLC

Recruiting

Wilmington, North Carolina, United States, 28401

Accellacare - Winston-Salem

Recruiting

Winston-Salem, North Carolina, United States, 27103

Wake Forest Baptist Health

Recruiting

Winston-Salem, North Carolina, United States, 27157

CTI Clinical Research Center

Recruiting

Cincinnati, Ohio, United States, 45212

VA Northeast Ohio Healthcare System Louis Stokes Cleveland VA Medical Center

Recruiting

Cleveland, Ohio, United States, 44106

Kaiser Permanente Center for Health Research

Recruiting

Portland, Oregon, United States, 97227

Capital Area Research, LLC

Recruiting

Camp Hill, Pennsylvania, United States, 17011

DM Clinical Research - Philadelphia

Recruiting

Philadelphia, Pennsylvania, United States, 19107

Walker Family Care

Recruiting

Little River, South Carolina, United States, 29566

Velocity Clinical Research, Spartanburg

Recruiting

Spartanburg, South Carolina, United States, 29303

New Phase Research and Development

Recruiting

Knoxville, Tennessee, United States, 37909

Clinical Neuroscience Solutions Inc.

Recruiting

Memphis, Tennessee, United States, 38119

The Vanderbilt Vaccine Research Program Clinic at The Village at Vanderbilt

Recruiting

Nashville, Tennessee, United States, 37212

Vanderbilt Investigational Drug Service (IDS)

Recruiting

Nashville, Tennessee, United States, 37232

Vanderbilt University Medical Center

Recruiting

Nashville, Tennessee, United States, 37232

Vanderbilt Vaccine Research Program Laboratory

Recruiting

Nashville, Tennessee, United States, 37232

Vanderbilt Vaccine Research Program

Recruiting

Nashville, Tennessee, United States, 37232

Family Health Watch - KeyPoint Clinical Research

Recruiting

Dallas, Texas, United States, 75237

KeyPoint Clinical Research

Recruiting

Dallas, Texas, United States, 75240

North Texas Infectious Diseases Consultants, P.A

Recruiting

Dallas, Texas, United States, 75246

Cedar Health Research - Euless

Recruiting

Euless, Texas, United States, 76040

Baylor College of Medicine

Recruiting

Houston, Texas, United States, 77030

Memorial Hermann Hospital - TMC

Recruiting

Houston, Texas, United States, 77030

The University of Texas Health Science Center at Houston

Recruiting

Houston, Texas, United States, 77030

UT Physicians

Recruiting

Houston, Texas, United States, 77030

DM Clinical Research- Cyfair

Recruiting

Houston, Texas, United States, 77065

Mercury Clinical Research - Santa Clara Family Clinic

Recruiting

Houston, Texas, United States, 77087

Dynamed Clinical Research, LP d/b/a DM Clinical Research

Recruiting

Tomball, Texas, United States, 77375

Northwest Houston Heart Center

Recruiting

Tomball, Texas, United States, 77375

J. Lewis Research, Inc. / Foothill Family Clinic South

Recruiting

Salt Lake City, Utah, United States, 84121

The University of Vermont Medical Center Inc.

Recruiting

Burlington, Vermont, United States, 05401

UVM Larner College of Medicine MMG/VCT

Recruiting

Burlington, Vermont, United States, 05401

Clinical Research Partners, LLC

Recruiting

Richmond, Virginia, United States, 23226

Providence Regional Medical Center Everett

Recruiting

Everett, Washington, United States, 98201

Kaiser Permanente Washington Health Research Institute (KPWHRI)

Recruiting

Seattle, Washington, United States, 98101

University of Washington - Harborview Medical Center

Recruiting

Seattle, Washington, United States, 98104

More Information

Sponsor

Pfizer

Last update posted

Aug 14, 2026

Last verified

Aug, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Pfizer on 2026-08-14.