Actively Recruiting
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
Led by Pfizer · Updated on 2026-05-26
32000
Participants Needed
174
Research Sites
25 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are evaluating the effectiveness, safety, and tolerability of a vaccine designed to reduce Clostridioides difficile (C. difficile) infections in adults aged 65 years and older. This phase 3 study compares the vaccine to a placebo in a group of older adults who have recent or planned contact with healthcare systems or recent antibiotic use. The purpose is to understand how well the vaccine works to prevent infections and to monitor any side effects or reactions. Participants will receive either the C. difficile vaccine or a placebo shot injected into the upper arm muscle. The study is randomized, double-blinded, and placebo-controlled. The vaccination period includes two doses and participants will be monitored for up to about three and a half years. Follow-up includes three planned clinical visits and three phone visits initially, then yearly clinic visits until the study ends. Participants are asked to report and save stool samples if they experience three or more loose stools in 24 hours to check for possible infection. During the study, researchers will track local and systemic reactions to the vaccine within seven days after each shot, adverse events up to one month after each vaccination, and serious adverse events for up to 18 months after the last dose. The main measurement is the occurrence of medically attended primary C. difficile infections from two weeks after the second vaccination through the surveillance period. Safety monitoring and annual visits will continue until the study is completed, which could be sooner or later depending on infection rates.
CONDITIONS
Brief Title
A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
Who Can Participate
Eligibility Criteria
You may qualify if you...
- People aged 65 years or older
- Recent or planned contact with healthcare systems or recent antibiotic use
- Willingness to receive study vaccinations and follow study procedures
You will not qualify if you...
- Previous Clostridioides difficile infection
- Surgery to remove part of the small or large intestine
- Frequent diarrhea (three or more loose stools per day, more than once a month)
- Prior receipt of a C. difficile vaccine or special antibody treatment
- History of serious allergic reaction to vaccines or study vaccine components
- Weakened immune system due to disease or treatment
- Presence of metastatic cancer, kidney failure, or other serious health problems
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Up to 2 doses over a short period
Participants receive either the C.difficile vaccine or a saline placebo as intramuscular injections.
2 vaccination visits (in-person)
Duration - Up to approximately 3.5 years
Participants are monitored for vaccine safety and the occurrence of Clostridioides difficile infection.
Periodic visits during surveillance period
Trial Site Locations
Total: 174 locations
1
North Alabama Research Center
Athens, Alabama, United States, 35611
Actively Recruiting
2
Lakeview Clinical Research
Guntersville, Alabama, United States, 35976
Actively Recruiting
3
Medical Affiliated Research Center
Huntsville, Alabama, United States, 35801
Actively Recruiting
4
Epic Medical Research-Sun City
Sun City, Arizona, United States, 85351
Actively Recruiting
5
Applied Research Center of Arkansas
Little Rock, Arkansas, United States, 72205
Actively Recruiting
6
Kaiser Permanente Daly City
Daly City, California, United States, 94015
Actively Recruiting
7
Kaiser Permanente Los Angeles Medical Center
Los Angeles, California, United States, 90027
Actively Recruiting
8
Kaiser Permanente Oncology Pharmacy #014C
Los Angeles, California, United States, 90027
Actively Recruiting
9
Sacramento VA Medical Center
Mather, California, United States, 95655
Not Yet Recruiting
10
Kaiser Permanente Oakland
Oakland, California, United States, 94611
Actively Recruiting
11
Kaiser Permanente Ontario Medical Center
Ontario, California, United States, 91761
Actively Recruiting
12
Southern California Permanente Medical Group
Pasadena, California, United States, 91101
Actively Recruiting
13
Kaiser Permanente Roseville
Roseville, California, United States, 95661
Actively Recruiting
14
Kaiser Permanente Sacramento
Sacramento, California, United States, 95815
Actively Recruiting
15
Kaiser Permanente South Sacramento
Sacramento, California, United States, 95823
Actively Recruiting
16
Velocity Clinical Research, San Bernardino
San Bernardino, California, United States, 92408
Actively Recruiting
17
Kaiser Permanente - San Diego Medical Center
San Diego, California, United States, 92123
Actively Recruiting
18
Kaiser Permanente Viewridge Medical Office
San Diego, California, United States, 92123
Actively Recruiting
19
Kaiser Permanente San Jose
San Jose, California, United States, 95119
Actively Recruiting
20
Carbon Health - San Mateo - Hillsdale Mall
San Mateo, California, United States, 94403
Actively Recruiting
21
Kaiser Permanente Santa Clara
Santa Clara, California, United States, 95051
Actively Recruiting
22
Med Partners, Inc. dba Premiere Medical Center of Burbank, Inc.
Toluca Lake, California, United States, 91602
Actively Recruiting
23
Kaiser Permanente Walnut Creek
Walnut Creek, California, United States, 94596
Actively Recruiting
24
Diablo Clinical Research, Inc.
Walnut Creek, California, United States, 94598
Actively Recruiting
25
GW Vaccine Research Unit
Washington D.C., District of Columbia, United States, 20037
Actively Recruiting
26
The GW Medical Faculty Associates
Washington D.C., District of Columbia, United States, 20037
Actively Recruiting
27
Bay Pines VA Healthcare System
Bay Pines, Florida, United States, 33744
Actively Recruiting
28
Proactive Clinical Research,LLC
Fort Lauderdale, Florida, United States, 33308
Actively Recruiting
29
Indago Research & Health Center, Inc
Hialeah, Florida, United States, 33012
Actively Recruiting
30
Clinical Neuroscience Solutions, Inc. dba CNS Healthcare
Jacksonville, Florida, United States, 32256
Actively Recruiting
31
M3 Wake Research - Lake City
Lake City, Florida, United States, 32055
Actively Recruiting
32
South Florida Research Organization
Medley, Florida, United States, 33166
Actively Recruiting
33
Care Research Inc
Miami, Florida, United States, 33130
Actively Recruiting
34
Entrust Clinical Research
Miami, Florida, United States, 33176
Actively Recruiting
35
Charisma Medical and Research Center
Miami Lakes, Florida, United States, 33014
Actively Recruiting
36
Palm Springs Community Health Center
Miami Lakes, Florida, United States, 33014
Actively Recruiting
37
Innovation Medical Research Center
Palmetto Bay, Florida, United States, 33157
Not Yet Recruiting
38
Angels Clinical Research Institute
Tampa, Florida, United States, 33614
Actively Recruiting
39
Emory Steiner Building Research Center
Atlanta, Georgia, United States, 30303
Actively Recruiting
40
Emory University Woodruff Extension Building (WEB)
Atlanta, Georgia, United States, 30303
Actively Recruiting
41
Centricity Research Columbus Georgia Multispecialty
Columbus, Georgia, United States, 31904
Actively Recruiting
42
The Hope Clinic of Emory University
Decatur, Georgia, United States, 30030
Actively Recruiting
43
Velocity Clinical Research, Savannah
Savannah, Georgia, United States, 31406
Actively Recruiting
44
DM Clinical Research - Chicago
Melrose Park, Illinois, United States, 60160
Actively Recruiting
45
Accellacare - McFarland
Ames, Iowa, United States, 50010
Actively Recruiting
46
McFarland Clinic, PC
Ames, Iowa, United States, 50010
Actively Recruiting
47
Velocity Clinical Research, Sioux City
Sioux City, Iowa, United States, 51106
Actively Recruiting
48
AMR Clinical
Newton, Kansas, United States, 67114
Actively Recruiting
49
Ochsner Medical Complex - The Grove
Baton Rouge, Louisiana, United States, 70836
Actively Recruiting
50
Ochsner Clinic Foundation - Kenner Clinical Trials Unit
Kenner, Louisiana, United States, 70065
Actively Recruiting
51
Ochsner Lafayette General Medical Center
Lafayette, Louisiana, United States, 70503
Actively Recruiting
52
Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland, United States, 21205
Not Yet Recruiting
53
Revive Research Institute, Inc.
Southfield, Michigan, United States, 48075
Actively Recruiting
54
DM Clinical Research - Detroit
Southfield, Michigan, United States, 48076
Actively Recruiting
55
Washington University School of Medicine
St Louis, Missouri, United States, 63110
Actively Recruiting
56
Sundance Clinical Research
St Louis, Missouri, United States, 63141
Actively Recruiting
57
Velocity Clinical Research, Grand Island
Grand Island, Nebraska, United States, 68803
Actively Recruiting
58
University of Nebraska Medical Center
Omaha, Nebraska, United States, 68105
Actively Recruiting
59
Velocity Clinical Research, Omaha
Omaha, Nebraska, United States, 68134
Actively Recruiting
60
University Of Nebraska Medical Center
Omaha, Nebraska, United States, 68198
Actively Recruiting
61
Renown Center for Advanced Medicine
Reno, Nevada, United States, 89502
Actively Recruiting
62
Renown Regional Medical Center
Reno, Nevada, United States, 89502
Actively Recruiting
63
University Health
Reno, Nevada, United States, 89519
Actively Recruiting
64
Hackensack Meridian Health Hackensack University Medical Center
Hackensack, New Jersey, United States, 07601
Actively Recruiting
65
HMH David Jurist Research Building
Hackensack, New Jersey, United States, 07601
Actively Recruiting
66
HMH Hackensack University Medical Center
Hackensack, New Jersey, United States, 07601
Actively Recruiting
67
Hackensack Meridian Jersey Shore University Medical Center
Neptune City, New Jersey, United States, 07753
Actively Recruiting
68
HOPE Tower at Jersey Shore University Medical Center
Neptune City, New Jersey, United States, 07753
Actively Recruiting
69
Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, United States, 08901
Not Yet Recruiting
70
South Jersey Infectious Disease
Somers Point, New Jersey, United States, 08244
Actively Recruiting
71
Albuquerque Clinical Trials, Inc.
Albuquerque, New Mexico, United States, 87102
Actively Recruiting
72
NYU Langone Health
Brooklyn, New York, United States, 11220
Actively Recruiting
73
Upstate Global Health Institute
East Syracuse, New York, United States, 13057
Actively Recruiting
74
Mount Sinai Queens
Long Island City, New York, United States, 11102
Actively Recruiting
75
North Shore University Hospital
Manhasset, New York, United States, 11030
Actively Recruiting
76
Northwell Health Infectious Disease
Manhasset, New York, United States, 11030
Actively Recruiting
77
NYU Langone Health
Mineola, New York, United States, 11501
Actively Recruiting
78
Northern Westchester Hospital
Mount Kisco, New York, United States, 10549
Actively Recruiting
79
NYU Langone Health
New York, New York, United States, 10016
Actively Recruiting
80
Mount Sinai West
New York, New York, United States, 10019
Actively Recruiting
81
Mount Sinai Morningside
New York, New York, United States, 10025
Actively Recruiting
82
Icahn School of Medicine at Mount Sinai
New York, New York, United States, 10029
Actively Recruiting
83
Columbia University Irving Medical Center
New York, New York, United States, 10032
Actively Recruiting
84
Rochester Clinical Research, LLC
Rochester, New York, United States, 14609
Actively Recruiting
85
Phelps Hospital Geriatric Medicine & Improvement Science
Sleepy Hollow, New York, United States, 10591
Actively Recruiting
86
Montefiore Medical Center
The Bronx, New York, United States, 10467
Actively Recruiting
87
James J. Peters VA Medical Center
The Bronx, New York, United States, 10468
Not Yet Recruiting
88
Accellacare - Cary
Cary, North Carolina, United States, 27518
Actively Recruiting
89
Duke Vaccine and Trials Unit
Durham, North Carolina, United States, 27703
Actively Recruiting
90
Medication Management
Greensboro, North Carolina, United States, 27405
Actively Recruiting
91
Accellacare - Hickory
Hickory, North Carolina, United States, 28601
Actively Recruiting
92
Atrium Health Wake Forest Baptist Infectious Disease-High Point
High Point, North Carolina, United States, 27262
Actively Recruiting
93
Accellacare - Raleigh
Raleigh, North Carolina, United States, 27609
Actively Recruiting
94
Duke University Health System
Raleigh, North Carolina, United States, 27609
Actively Recruiting
95
Raleigh Medical Group P.A.
Raleigh, North Carolina, United States, 27609
Actively Recruiting
96
Accellacare - Salisbury
Salisbury, North Carolina, United States, 28144
Actively Recruiting
97
Accellacare - Wilmington
Wilmington, North Carolina, United States, 28401
Actively Recruiting
98
Wilmington Health, PLLC
Wilmington, North Carolina, United States, 28401
Actively Recruiting
99
Accellacare - Winston-Salem
Winston-Salem, North Carolina, United States, 27103
Actively Recruiting
100
Wake Forest Baptist Health
Winston-Salem, North Carolina, United States, 27157
Actively Recruiting
101
CTI Clinical Research Center
Cincinnati, Ohio, United States, 45212
Actively Recruiting
102
VA Northeast Ohio Healthcare System Louis Stokes Cleveland VA Medical Center
Cleveland, Ohio, United States, 44106
Actively Recruiting
103
Kaiser Permanente Center for Health Research
Portland, Oregon, United States, 97227
Actively Recruiting
104
Capital Area Research, LLC
Camp Hill, Pennsylvania, United States, 17011
Actively Recruiting
105
DM Clinical Research - Philadelphia
Philadelphia, Pennsylvania, United States, 19107
Actively Recruiting
106
Walker Family Care
Little River, South Carolina, United States, 29566
Actively Recruiting
107
Trial Management Associates, LLC
Myrtle Beach, South Carolina, United States, 29572
Actively Recruiting
108
Trial Management Associates
Myrtle Beach, South Carolina, United States, 29572
Actively Recruiting
109
Velocity Clinical Research, Spartanburg
Spartanburg, South Carolina, United States, 29303
Actively Recruiting
110
New Phase Research and Development
Knoxville, Tennessee, United States, 37909
Actively Recruiting
111
Clinical Neuroscience Solutions Inc.
Memphis, Tennessee, United States, 38119
Actively Recruiting
112
The Vanderbilt Vaccine Research Program Clinic at The Village at Vanderbilt
Nashville, Tennessee, United States, 37212
Not Yet Recruiting
113
Vanderbilt Investigational Drug Service (IDS)
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
114
Vanderbilt University Medical Center
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
115
Vanderbilt Vaccine Research Program Laboratory
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
116
Vanderbilt Vaccine Research Program
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
117
Family Health Watch - KeyPoint Clinical Research
Dallas, Texas, United States, 75237
Actively Recruiting
118
KeyPoint Clinical Research
Dallas, Texas, United States, 75240
Actively Recruiting
119
North Texas Infectious Diseases Consultants, P.A
Dallas, Texas, United States, 75246
Actively Recruiting
120
Cedar Health Research - Euless
Euless, Texas, United States, 76040
Actively Recruiting
121
Baylor College of Medicine
Houston, Texas, United States, 77030
Actively Recruiting
122
Memorial Hermann Hospital - TMC
Houston, Texas, United States, 77030
Not Yet Recruiting
123
The University of Texas Health Science Center at Houston
Houston, Texas, United States, 77030
Not Yet Recruiting
124
UT Physicians
Houston, Texas, United States, 77030
Not Yet Recruiting
125
DM Clinical Research- Cyfair
Houston, Texas, United States, 77065
Actively Recruiting
126
Mercury Clinical Research - Santa Clara Family Clinic
Houston, Texas, United States, 77087
Actively Recruiting
127
Dynamed Clinical Research, LP d/b/a DM Clinical Research
Tomball, Texas, United States, 77375
Actively Recruiting
128
Northwest Houston Heart Center
Tomball, Texas, United States, 77375
Actively Recruiting
129
J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, United States, 84121
Actively Recruiting
130
The University of Vermont Medical Center Inc.
Burlington, Vermont, United States, 05401
Actively Recruiting
131
UVM Larner College of Medicine MMG/VCT
Burlington, Vermont, United States, 05401
Actively Recruiting
132
Clinical Research Partners, LLC
Richmond, Virginia, United States, 23226
Actively Recruiting
133
Providence Regional Medical Center Everett
Everett, Washington, United States, 98201
Actively Recruiting
134
Kaiser Permanente Washington Health Research Institute (KPWHRI)
Seattle, Washington, United States, 98101
Actively Recruiting
135
University of Washington - Harborview Medical Center
Seattle, Washington, United States, 98104
Actively Recruiting
136
Clinica Del Niño Y La Madre
Mar del Plata, Buenos Aires, Argentina, 7600
Actively Recruiting
137
Fundación Huésped
Buenos Aires, Buenos Aires F.D., Argentina, 1427
Actively Recruiting
138
Equipo Ciencia
Buenos Aires, Buenos Aires F.D., Argentina, C1428BNF
Actively Recruiting
139
Clinica Privada del Sol S.A
Córdoba, Córdoba Province, Argentina, X5000IIH
Actively Recruiting
140
CDC Centro Médico
Lujan de Cuyo, Mendoza Province, Argentina, 5505
Not Yet Recruiting
141
Sanatorio Sagrado Corazón
Buenos Aires, Argentina, 1039
Actively Recruiting
142
Centro Medico Barrio Parque
Buenos Aires, Argentina, 1425
Actively Recruiting
143
Investigaciones Clínicas Salta (ICSAL)
Salta, Argentina, A4400
Not Yet Recruiting
144
Kojunkai Daido Clinic
Nagoya, Aichi-ken, Japan, 457-8511
Not Yet Recruiting
145
Kamiiida daiichi General Hospital
Nagoya, Aichi-ken, Japan, 462-0802
Not Yet Recruiting
146
Aso Iizuka Hospital
Iizuka-shi, Fukuoka, Japan, 820-8505
Not Yet Recruiting
147
Seishinkai Inoue Hospital
Itoshima, Fukuoka, Japan, 819-1104
Not Yet Recruiting
148
Japan Community Healthcare Organization Kyushu Hospital
Kitakyushu-shi, Fukuoka, Japan, 806-8501
Not Yet Recruiting
149
Fukuoka Shinmizumaki Hospital
Onga-gun, Fukuoka, Japan, 807-0051
Not Yet Recruiting
150
Koga General Hospital
Koga, Ibaraki, Japan, 306-0041
Not Yet Recruiting
151
Japanese Red Cross Kumamoto Hospital
Kumamoto, Kumamoto, Japan, 861-8520, 862-8520
Not Yet Recruiting
152
National Hospital Organization Nagasaki Medical Center
Ōmura, Nagasaki, Japan, 856-8562
Actively Recruiting
153
Nanbu Tokushukai Hospital
Shimajiri, Okinawa, Japan, 901-0417
Not Yet Recruiting
154
Nozaki Tokushukai Hospital
Daitō, Osaka, Japan, 547-0074
Not Yet Recruiting
155
Tokyo-Eki Center-building Clinic
Chuo-ku, Tokyo, Japan, 103-0027
Actively Recruiting
156
Newquay Health Centre
Newquay, Cornwall, United Kingdom, TR7 1RU
Actively Recruiting
157
Royal Devon & Exeter Hospital
Exeter, Devon, United Kingdom, EX2 5DW
Actively Recruiting
158
Knowle House Surgery
Plymouth, Devon, United Kingdom, PL5 3JB
Actively Recruiting
159
Brunel Medical Practice (St Marychurch)
Torquay, Devon, United Kingdom, TQ1 4QX
Not Yet Recruiting
160
Panthera Biopartners - Preston
Preston, England, United Kingdom, PR2 9QB
Actively Recruiting
161
Synexus Scotland Clinical Research Centre
Glasgow, Glasgow CITY, United Kingdom, ML4 3NJ
Not Yet Recruiting
162
Southampton General Hospital
Southampton, Hampshire, United Kingdom, SO16 6YD
Actively Recruiting
163
Layton Medical Centre
Blackpool, Lancashire, United Kingdom, FY3 7EN
Actively Recruiting
164
Panthera Biopartners - Manchester
Rochdale, Manchester, United Kingdom, OL11 4AU
Actively Recruiting
165
Panthera Clinic - York
York, North Yorkshire, United Kingdom, YO24 4LJ
Actively Recruiting
166
Lakeside Surgery
Corby, Northamptonshire, United Kingdom, NN17 2UR
Actively Recruiting
167
Ormeau Clinical Trials
Belfast, Northern Ireland, United Kingdom, BT2 8BG
Actively Recruiting
168
Cheadle Community Hospital
Cheadle, Staffordshire, United Kingdom, ST10 1NS
Actively Recruiting
169
Synexus Midlands Clinical Research Centre
Birmingham, WEST Midlands, United Kingdom, B15 2SQ
Not Yet Recruiting
170
North Wales Clinical Research Facility
Wrexham, Wrexham [wrecsam Gb-wrc], United Kingdom, LL13 7YP
Not Yet Recruiting
171
Panthera Biopartners - Glasgow
Glasgow, United Kingdom, G51 4RY
Actively Recruiting
172
Manchester Royal Infirmary
Manchester, United Kingdom, M13 9WU
Not Yet Recruiting
173
Synexus Manchester Clinical Research Centre
Manchester, United Kingdom, M15 6SE
Actively Recruiting
174
Panthera Biopartners - Sheffield
Sheffield, United Kingdom, S2 5FX
Actively Recruiting
Research Team
P
Pfizer CT.gov Call Center
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
PREVENTION
Number of Arms
2
Frequently Asked Questions
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