A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
BEETHOVEN
A PHASE 3, PLACEBO-CONTROLLED, DOUBLE-BLINDED, RANDOMIZED STUDY TO EVALUATE THE EFFICACY, SAFETY, AND TOLERABILITY OF A CLOSTRIDIOIDES DIFFICILE VACCINE IN ADULTS 65 YEARS OF AGE AND OLDER
1 other identifier
interventional
32,000
4 countries
174
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 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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for phase_3
Started Dec 2025
Typical duration for phase_3
174 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
December 5, 2025
CompletedStudy Start
First participant enrolled
December 10, 2025
CompletedFirst Posted
Study publicly available on registry
December 15, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
December 11, 2028
ExpectedStudy Completion
Last participant's last visit for all outcomes
June 7, 2029
May 26, 2026
May 1, 2026
3 years
December 5, 2025
May 22, 2026
Conditions
Outcome Measures
Primary Outcomes (7)
The percentage of participants reporting local reactions
Injection site pain, redness, and swelling as self-reported in electronic diaries
For 7 days after each vaccination
The percentage of participants reporting systemic events
Fever, vomiting, fatigue, headache, muscle pain, and joint pain as self-reported in electronic diaries
For 7 days after each vaccination
Percentage of participants reporting adverse events
As elicited by investigator site staff
From each vaccination through 1 month after each vaccination
Percentage of participants reporting serious adverse events
As elicited by investigator site staff
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)
First episode of medically attended and clinically meaningful primary CDI incidence per 1000 person- years of follow- up
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
First episode of medically attended primary CDI incidence per 1000 person- years of follow- up
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
First episode of clinically meaningful primary CDI incidence per 1000 person- years of follow- up
from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
Secondary Outcomes (4)
The incidence of antibiotic use in the treatment of a first episode of the primary CDI
from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
The incidence of severe primary CDI as defined by Infectious Diseases Society of America (IDSA)/ Society for Healthcare Epidemiology of America (SHEA)
from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
The incidence of a first episode of primary CDI (any severity)
from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
The incidence of all CDI (primary and recurrent)
from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
Study Arms (2)
C.difficile vaccine
EXPERIMENTALNovel vaccine formulation
Saline Placebo
OTHERInterventions
C.difficile vaccine given as an intramuscular injection
Eligibility Criteria
You may qualify if:
- People with recent or future planned contact with healthcare systems or who have recently received antibiotics.
You may not qualify if:
- 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, kidney failure, or another serious health problem.
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Pfizerlead
Study Sites (174)
North Alabama Research Center
Athens, Alabama, 35611, United States
Lakeview Clinical Research
Guntersville, Alabama, 35976, United States
Medical Affiliated Research Center
Huntsville, Alabama, 35801, United States
Epic Medical Research-Sun City
Sun City, Arizona, 85351, United States
Applied Research Center of Arkansas
Little Rock, Arkansas, 72205, United States
Kaiser Permanente Daly City
Daly City, California, 94015, United States
Kaiser Permanente Los Angeles Medical Center
Los Angeles, California, 90027, United States
Kaiser Permanente Oncology Pharmacy #014C
Los Angeles, California, 90027, United States
Sacramento VA Medical Center
Mather, California, 95655, United States
Kaiser Permanente Oakland
Oakland, California, 94611, United States
Kaiser Permanente Ontario Medical Center
Ontario, California, 91761, United States
Southern California Permanente Medical Group
Pasadena, California, 91101, United States
Kaiser Permanente Roseville
Roseville, California, 95661, United States
Kaiser Permanente Sacramento
Sacramento, California, 95815, United States
Kaiser Permanente South Sacramento
Sacramento, California, 95823, United States
Velocity Clinical Research, San Bernardino
San Bernardino, California, 92408, United States
Kaiser Permanente - San Diego Medical Center
San Diego, California, 92123, United States
Kaiser Permanente Viewridge Medical Office
San Diego, California, 92123, United States
Kaiser Permanente San Jose
San Jose, California, 95119, United States
Carbon Health - San Mateo - Hillsdale Mall
San Mateo, California, 94403, United States
Kaiser Permanente Santa Clara
Santa Clara, California, 95051, United States
Med Partners, Inc. dba Premiere Medical Center of Burbank, Inc.
Toluca Lake, California, 91602, United States
Kaiser Permanente Walnut Creek
Walnut Creek, California, 94596, United States
Diablo Clinical Research, Inc.
Walnut Creek, California, 94598, United States
GW Vaccine Research Unit
Washington D.C., District of Columbia, 20037, United States
The GW Medical Faculty Associates
Washington D.C., District of Columbia, 20037, United States
Bay Pines VA Healthcare System
Bay Pines, Florida, 33744, United States
Proactive Clinical Research,LLC
Fort Lauderdale, Florida, 33308, United States
Indago Research & Health Center, Inc
Hialeah, Florida, 33012, United States
Clinical Neuroscience Solutions, Inc. dba CNS Healthcare
Jacksonville, Florida, 32256, United States
M3 Wake Research - Lake City
Lake City, Florida, 32055, United States
South Florida Research Organization
Medley, Florida, 33166, United States
Care Research Inc
Miami, Florida, 33130, United States
Entrust Clinical Research
Miami, Florida, 33176, United States
Charisma Medical and Research Center
Miami Lakes, Florida, 33014, United States
Palm Springs Community Health Center
Miami Lakes, Florida, 33014, United States
Innovation Medical Research Center
Palmetto Bay, Florida, 33157, United States
Angels Clinical Research Institute
Tampa, Florida, 33614, United States
Emory Steiner Building Research Center
Atlanta, Georgia, 30303, United States
Emory University Woodruff Extension Building (WEB)
Atlanta, Georgia, 30303, United States
Centricity Research Columbus Georgia Multispecialty
Columbus, Georgia, 31904, United States
The Hope Clinic of Emory University
Decatur, Georgia, 30030, United States
Velocity Clinical Research, Savannah
Savannah, Georgia, 31406, United States
DM Clinical Research - Chicago
Melrose Park, Illinois, 60160, United States
Accellacare - McFarland
Ames, Iowa, 50010, United States
McFarland Clinic, PC
Ames, Iowa, 50010, United States
Velocity Clinical Research, Sioux City
Sioux City, Iowa, 51106, United States
AMR Clinical
Newton, Kansas, 67114, United States
Ochsner Medical Complex - The Grove
Baton Rouge, Louisiana, 70836, United States
Ochsner Clinic Foundation - Kenner Clinical Trials Unit
Kenner, Louisiana, 70065, United States
Ochsner Lafayette General Medical Center
Lafayette, Louisiana, 70503, United States
Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland, 21205, United States
Revive Research Institute, Inc.
Southfield, Michigan, 48075, United States
DM Clinical Research - Detroit
Southfield, Michigan, 48076, United States
Washington University School of Medicine
St Louis, Missouri, 63110, United States
Sundance Clinical Research
St Louis, Missouri, 63141, United States
Velocity Clinical Research, Grand Island
Grand Island, Nebraska, 68803, United States
University of Nebraska Medical Center
Omaha, Nebraska, 68105, United States
Velocity Clinical Research, Omaha
Omaha, Nebraska, 68134, United States
University Of Nebraska Medical Center
Omaha, Nebraska, 68198, United States
Renown Center for Advanced Medicine
Reno, Nevada, 89502, United States
Renown Regional Medical Center
Reno, Nevada, 89502, United States
University Health
Reno, Nevada, 89519, United States
Hackensack Meridian Health Hackensack University Medical Center
Hackensack, New Jersey, 07601, United States
HMH David Jurist Research Building
Hackensack, New Jersey, 07601, United States
HMH Hackensack University Medical Center
Hackensack, New Jersey, 07601, United States
Hackensack Meridian Jersey Shore University Medical Center
Neptune City, New Jersey, 07753, United States
HOPE Tower at Jersey Shore University Medical Center
Neptune City, New Jersey, 07753, United States
Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, 08901, United States
South Jersey Infectious Disease
Somers Point, New Jersey, 08244, United States
Albuquerque Clinical Trials, Inc.
Albuquerque, New Mexico, 87102, United States
NYU Langone Health
Brooklyn, New York, 11220, United States
Upstate Global Health Institute
East Syracuse, New York, 13057, United States
Mount Sinai Queens
Long Island City, New York, 11102, United States
North Shore University Hospital
Manhasset, New York, 11030, United States
Northwell Health Infectious Disease
Manhasset, New York, 11030, United States
NYU Langone Health
Mineola, New York, 11501, United States
Northern Westchester Hospital
Mount Kisco, New York, 10549, United States
NYU Langone Health
New York, New York, 10016, United States
Mount Sinai West
New York, New York, 10019, United States
Mount Sinai Morningside
New York, New York, 10025, United States
Icahn School of Medicine at Mount Sinai
New York, New York, 10029, United States
Columbia University Irving Medical Center
New York, New York, 10032, United States
Rochester Clinical Research, LLC
Rochester, New York, 14609, United States
Phelps Hospital Geriatric Medicine & Improvement Science
Sleepy Hollow, New York, 10591, United States
Montefiore Medical Center
The Bronx, New York, 10467, United States
James J. Peters VA Medical Center
The Bronx, New York, 10468, United States
Accellacare - Cary
Cary, North Carolina, 27518, United States
Duke Vaccine and Trials Unit
Durham, North Carolina, 27703, United States
Medication Management
Greensboro, North Carolina, 27405, United States
Accellacare - Hickory
Hickory, North Carolina, 28601, United States
Atrium Health Wake Forest Baptist Infectious Disease-High Point
High Point, North Carolina, 27262, United States
Accellacare - Raleigh
Raleigh, North Carolina, 27609, United States
Duke University Health System
Raleigh, North Carolina, 27609, United States
Raleigh Medical Group P.A.
Raleigh, North Carolina, 27609, United States
Accellacare - Salisbury
Salisbury, North Carolina, 28144, United States
Accellacare - Wilmington
Wilmington, North Carolina, 28401, United States
Wilmington Health, PLLC
Wilmington, North Carolina, 28401, United States
Accellacare - Winston-Salem
Winston-Salem, North Carolina, 27103, United States
Wake Forest Baptist Health
Winston-Salem, North Carolina, 27157, United States
CTI Clinical Research Center
Cincinnati, Ohio, 45212, United States
VA Northeast Ohio Healthcare System Louis Stokes Cleveland VA Medical Center
Cleveland, Ohio, 44106, United States
Kaiser Permanente Center for Health Research
Portland, Oregon, 97227, United States
Capital Area Research, LLC
Camp Hill, Pennsylvania, 17011, United States
DM Clinical Research - Philadelphia
Philadelphia, Pennsylvania, 19107, United States
Walker Family Care
Little River, South Carolina, 29566, United States
Trial Management Associates, LLC
Myrtle Beach, South Carolina, 29572, United States
Trial Management Associates
Myrtle Beach, South Carolina, 29572, United States
Velocity Clinical Research, Spartanburg
Spartanburg, South Carolina, 29303, United States
New Phase Research and Development
Knoxville, Tennessee, 37909, United States
Clinical Neuroscience Solutions Inc.
Memphis, Tennessee, 38119, United States
The Vanderbilt Vaccine Research Program Clinic at The Village at Vanderbilt
Nashville, Tennessee, 37212, United States
Vanderbilt Investigational Drug Service (IDS)
Nashville, Tennessee, 37232, United States
Vanderbilt University Medical Center
Nashville, Tennessee, 37232, United States
Vanderbilt Vaccine Research Program Laboratory
Nashville, Tennessee, 37232, United States
Vanderbilt Vaccine Research Program
Nashville, Tennessee, 37232, United States
Family Health Watch - KeyPoint Clinical Research
Dallas, Texas, 75237, United States
KeyPoint Clinical Research
Dallas, Texas, 75240, United States
North Texas Infectious Diseases Consultants, P.A
Dallas, Texas, 75246, United States
Cedar Health Research - Euless
Euless, Texas, 76040, United States
Baylor College of Medicine
Houston, Texas, 77030, United States
Memorial Hermann Hospital - TMC
Houston, Texas, 77030, United States
The University of Texas Health Science Center at Houston
Houston, Texas, 77030, United States
UT Physicians
Houston, Texas, 77030, United States
DM Clinical Research- Cyfair
Houston, Texas, 77065, United States
Mercury Clinical Research - Santa Clara Family Clinic
Houston, Texas, 77087, United States
Dynamed Clinical Research, LP d/b/a DM Clinical Research
Tomball, Texas, 77375, United States
Northwest Houston Heart Center
Tomball, Texas, 77375, United States
J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, 84121, United States
The University of Vermont Medical Center Inc.
Burlington, Vermont, 05401, United States
UVM Larner College of Medicine MMG/VCT
Burlington, Vermont, 05401, United States
Clinical Research Partners, LLC
Richmond, Virginia, 23226, United States
Providence Regional Medical Center Everett
Everett, Washington, 98201, United States
Kaiser Permanente Washington Health Research Institute (KPWHRI)
Seattle, Washington, 98101, United States
University of Washington - Harborview Medical Center
Seattle, Washington, 98104, United States
Clinica Del Niño Y La Madre
Mar del Plata, Buenos Aires, 7600, Argentina
Fundación Huésped
Buenos Aires, Buenos Aires F.D., 1427, Argentina
Equipo Ciencia
Buenos Aires, Buenos Aires F.D., C1428BNF, Argentina
Clinica Privada del Sol S.A
Córdoba, Córdoba Province, X5000IIH, Argentina
CDC Centro Médico
Lujan de Cuyo, Mendoza Province, 5505, Argentina
Sanatorio Sagrado Corazón
Buenos Aires, 1039, Argentina
Centro Medico Barrio Parque
Buenos Aires, 1425, Argentina
Investigaciones Clínicas Salta (ICSAL)
Salta, A4400, Argentina
Kojunkai Daido Clinic
Nagoya, Aichi-ken, 457-8511, Japan
Kamiiida daiichi General Hospital
Nagoya, Aichi-ken, 462-0802, Japan
Aso Iizuka Hospital
Iizuka-shi, Fukuoka, 820-8505, Japan
Seishinkai Inoue Hospital
Itoshima, Fukuoka, 819-1104, Japan
Japan Community Healthcare Organization Kyushu Hospital
Kitakyushu-shi, Fukuoka, 806-8501, Japan
Fukuoka Shinmizumaki Hospital
Onga-gun, Fukuoka, 807-0051, Japan
Koga General Hospital
Koga, Ibaraki, 306-0041, Japan
Japanese Red Cross Kumamoto Hospital
Kumamoto, Kumamoto, 861-8520, 862-8520, Japan
National Hospital Organization Nagasaki Medical Center
Ōmura, Nagasaki, 856-8562, Japan
Nanbu Tokushukai Hospital
Shimajiri, Okinawa, 901-0417, Japan
Nozaki Tokushukai Hospital
Daitō, Osaka, 547-0074, Japan
Tokyo-Eki Center-building Clinic
Chuo-ku, Tokyo, 103-0027, Japan
Newquay Health Centre
Newquay, Cornwall, TR7 1RU, United Kingdom
Royal Devon & Exeter Hospital
Exeter, Devon, EX2 5DW, United Kingdom
Knowle House Surgery
Plymouth, Devon, PL5 3JB, United Kingdom
Brunel Medical Practice (St Marychurch)
Torquay, Devon, TQ1 4QX, United Kingdom
Panthera Biopartners - Preston
Preston, England, PR2 9QB, United Kingdom
Synexus Scotland Clinical Research Centre
Glasgow, Glasgow CITY, ML4 3NJ, United Kingdom
Southampton General Hospital
Southampton, Hampshire, SO16 6YD, United Kingdom
Layton Medical Centre
Blackpool, Lancashire, FY3 7EN, United Kingdom
Panthera Biopartners - Manchester
Rochdale, Manchester, OL11 4AU, United Kingdom
Panthera Clinic - York
York, North Yorkshire, YO24 4LJ, United Kingdom
Lakeside Surgery
Corby, Northamptonshire, NN17 2UR, United Kingdom
Ormeau Clinical Trials
Belfast, Northern Ireland, BT2 8BG, United Kingdom
Cheadle Community Hospital
Cheadle, Staffordshire, ST10 1NS, United Kingdom
Synexus Midlands Clinical Research Centre
Birmingham, WEST Midlands, B15 2SQ, United Kingdom
North Wales Clinical Research Facility
Wrexham, Wrexham [wrecsam Gb-wrc], LL13 7YP, United Kingdom
Panthera Biopartners - Glasgow
Glasgow, G51 4RY, United Kingdom
Manchester Royal Infirmary
Manchester, M13 9WU, United Kingdom
Synexus Manchester Clinical Research Centre
Manchester, M15 6SE, United Kingdom
Panthera Biopartners - Sheffield
Sheffield, S2 5FX, United Kingdom
Related Links
Study Officials
- STUDY DIRECTOR
Pfizer CT.gov Call Center
Pfizer
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 3
- Allocation
- RANDOMIZED
- Masking
- TRIPLE
- Who Masked
- PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
- Purpose
- PREVENTION
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
December 5, 2025
First Posted
December 15, 2025
Study Start
December 10, 2025
Primary Completion (Estimated)
December 11, 2028
Study Completion (Estimated)
June 7, 2029
Last Updated
May 26, 2026
Record last verified: 2026-05
Data Sharing
- IPD Sharing
- Will share
Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.