Actively Recruiting
A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
Led by Pfizer · Updated on 2026-04-22
32000
Participants Needed
158
Research Sites
182 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
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
Official 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 with recent or future planned contact with healthcare systems or who have recently received antibiotics.
You will not qualify if you...
- 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.
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Trial Site Locations
Total: 158 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
Not Yet Recruiting
11
Kaiser Permanente Ontario Medical Center
Ontario, California, United States, 91761
Actively Recruiting
12
Kaiser Permanente Roseville
Roseville, California, United States, 95661
Actively Recruiting
13
Kaiser Permanente Sacramento
Sacramento, California, United States, 95815
Actively Recruiting
14
Kaiser Permanente South Sacramento
Sacramento, California, United States, 95823
Actively Recruiting
15
Velocity Clinical Research, San Bernardino
San Bernardino, California, United States, 92408
Actively Recruiting
16
Kaiser Permanente - San Diego Medical Center
San Diego, California, United States, 92123
Actively Recruiting
17
Kaiser Permanente Viewridge Medical Office
San Diego, California, United States, 92123
Actively Recruiting
18
Kaiser Permanente San Jose
San Jose, California, United States, 95119
Actively Recruiting
19
Carbon Health - San Mateo - Hillsdale Mall
San Mateo, California, United States, 94403
Actively Recruiting
20
Kaiser Permanente Santa Clara
Santa Clara, California, United States, 95051
Actively Recruiting
21
Med Partners, Inc. dba Premiere Medical Center of Burbank, Inc.
Toluca Lake, California, United States, 91602
Actively Recruiting
22
Kaiser Permanente Walnut Creek
Walnut Creek, California, United States, 94596
Actively Recruiting
23
Diablo Clinical Research, Inc.
Walnut Creek, California, United States, 94598
Actively Recruiting
24
GW Vaccine Research Unit
Washington D.C., District of Columbia, United States, 20037
Actively Recruiting
25
The GW Medical Faculty Associates
Washington D.C., District of Columbia, United States, 20037
Actively Recruiting
26
Bay Pines VA Healthcare System
Bay Pines, Florida, United States, 33744
Not Yet Recruiting
27
Proactive Clinical Research,LLC
Fort Lauderdale, Florida, United States, 33308
Actively Recruiting
28
Indago Research & Health Center, Inc
Hialeah, Florida, United States, 33012
Actively Recruiting
29
Clinical Neuroscience Solutions, Inc. dba CNS Healthcare
Jacksonville, Florida, United States, 32256
Actively Recruiting
30
M3 Wake Research - Lake City
Lake City, Florida, United States, 32055
Actively Recruiting
31
South Florida Research Organization
Medley, Florida, United States, 33166
Actively Recruiting
32
Care Research Inc
Miami, Florida, United States, 33130
Actively Recruiting
33
Entrust Clinical Research
Miami, Florida, United States, 33176
Actively Recruiting
34
Charisma Medical and Research Center
Miami Lakes, Florida, United States, 33014
Actively Recruiting
35
Palm Springs Community Health Center
Miami Lakes, Florida, United States, 33014
Not Yet Recruiting
36
Innovation Medical Research Center
Palmetto Bay, Florida, United States, 33157
Not Yet Recruiting
37
Angels Clinical Research Institute
Tampa, Florida, United States, 33614
Actively Recruiting
38
Emory Steiner Building Research Center
Atlanta, Georgia, United States, 30303
Not Yet Recruiting
39
Emory University Woodruff Extension Building (WEB)
Atlanta, Georgia, United States, 30303
Not Yet Recruiting
40
Centricity Research Columbus Georgia Multispecialty
Columbus, Georgia, United States, 31904
Actively Recruiting
41
The Hope Clinic of Emory University
Decatur, Georgia, United States, 30030
Actively Recruiting
42
Velocity Clinical Research, Savannah
Savannah, Georgia, United States, 31406
Actively Recruiting
43
DM Clinical Research - Chicago
Melrose Park, Illinois, United States, 60160
Actively Recruiting
44
Accellacare - McFarland
Ames, Iowa, United States, 50010
Actively Recruiting
45
McFarland Clinic, PC
Ames, Iowa, United States, 50010
Actively Recruiting
46
Velocity Clinical Research, Sioux City
Sioux City, Iowa, United States, 51106
Actively Recruiting
47
AMR Clinical
Newton, Kansas, United States, 67114
Actively Recruiting
48
Ochsner Medical Complex - The Grove
Baton Rouge, Louisiana, United States, 70836
Not Yet Recruiting
49
Ochsner Clinic Foundation - Kenner Clinical Trials Unit
Kenner, Louisiana, United States, 70065
Not Yet Recruiting
50
Ochsner Lafayette General Medical Center
Lafayette, Louisiana, United States, 70503
Not Yet Recruiting
51
Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland, United States, 21205
Not Yet Recruiting
52
Revive Research Institute, Inc.
Southfield, Michigan, United States, 48075
Actively Recruiting
53
DM Clinical Research - Detroit
Southfield, Michigan, United States, 48076
Actively Recruiting
54
Washington University School of Medicine
St Louis, Missouri, United States, 63110
Actively Recruiting
55
Sundance Clinical Research
St Louis, Missouri, United States, 63141
Actively Recruiting
56
Velocity Clinical Research, Grand Island
Grand Island, Nebraska, United States, 68803
Actively Recruiting
57
University of Nebraska Medical Center
Omaha, Nebraska, United States, 68105
Not Yet Recruiting
58
Velocity Clinical Research, Omaha
Omaha, Nebraska, United States, 68134
Actively Recruiting
59
University Of Nebraska Medical Center
Omaha, Nebraska, United States, 68198
Not Yet Recruiting
60
Renown Center for Advanced Medicine
Reno, Nevada, United States, 89502
Actively Recruiting
61
Renown Regional Medical Center
Reno, Nevada, United States, 89502
Actively Recruiting
62
University Health
Reno, Nevada, United States, 89519
Actively Recruiting
63
Hackensack Meridian Health Hackensack University Medical Center
Hackensack, New Jersey, United States, 07601
Actively Recruiting
64
HMH David Jurist Research Building
Hackensack, New Jersey, United States, 07601
Actively Recruiting
65
HMH Hackensack University Medical Center
Hackensack, New Jersey, United States, 07601
Actively Recruiting
66
Hackensack Meridian Jersey Shore University Medical Center
Neptune City, New Jersey, United States, 07753
Actively Recruiting
67
HOPE Tower at Jersey Shore University Medical Center
Neptune City, New Jersey, United States, 07753
Actively Recruiting
68
Rutgers Robert Wood Johnson Medical School
New Brunswick, New Jersey, United States, 08901
Not Yet Recruiting
69
South Jersey Infectious Disease
Somers Point, New Jersey, United States, 08244
Actively Recruiting
70
Albuquerque Clinical Trials, Inc.
Albuquerque, New Mexico, United States, 87102
Actively Recruiting
71
NYU Langone Health
Brooklyn, New York, United States, 11220
Actively Recruiting
72
Upstate Global Health Institute
East Syracuse, New York, United States, 13057
Actively Recruiting
73
Mount Sinai Queens
Long Island City, New York, United States, 11102
Actively Recruiting
74
North Shore University Hospital
Manhasset, New York, United States, 11030
Actively Recruiting
75
Northwell Health Infectious Disease
Manhasset, New York, United States, 11030
Actively Recruiting
76
NYU Langone Health
Mineola, New York, United States, 11501
Actively Recruiting
77
Northern Westchester Hospital
Mount Kisco, New York, United States, 10549
Actively Recruiting
78
NYU Langone Health
New York, New York, United States, 10016
Actively Recruiting
79
Mount Sinai West
New York, New York, United States, 10019
Actively Recruiting
80
Mount Sinai Morningside
New York, New York, United States, 10025
Actively Recruiting
81
Icahn School of Medicine at Mount Sinai
New York, New York, United States, 10029
Actively Recruiting
82
Columbia University Irving Medical Center
New York, New York, United States, 10032
Not Yet Recruiting
83
Rochester Clinical Research, LLC
Rochester, New York, United States, 14609
Actively Recruiting
84
Phelps Hospital Geriatric Medicine & Improvement Science
Sleepy Hollow, New York, United States, 10591
Actively Recruiting
85
Montefiore Medical Center
The Bronx, New York, United States, 10467
Actively Recruiting
86
Accellacare - Cary
Cary, North Carolina, United States, 27518
Actively Recruiting
87
Duke Vaccine and Trials Unit
Durham, North Carolina, United States, 27703
Actively Recruiting
88
Medication Management
Greensboro, North Carolina, United States, 27405
Actively Recruiting
89
Accellacare - Hickory
Hickory, North Carolina, United States, 28601
Actively Recruiting
90
Atrium Health Wake Forest Baptist Infectious Disease-High Point
High Point, North Carolina, United States, 27262
Actively Recruiting
91
Accellacare - Raleigh
Raleigh, North Carolina, United States, 27609
Actively Recruiting
92
Duke University Health System
Raleigh, North Carolina, United States, 27609
Actively Recruiting
93
Accellacare - Salisbury
Salisbury, North Carolina, United States, 28144
Actively Recruiting
94
Accellacare - Wilmington
Wilmington, North Carolina, United States, 28401
Actively Recruiting
95
Accellacare - Winston-Salem
Winston-Salem, North Carolina, United States, 27103
Actively Recruiting
96
Wake Forest Baptist Health
Winston-Salem, North Carolina, United States, 27157
Actively Recruiting
97
CTI Clinical Research Center
Cincinnati, Ohio, United States, 45212
Actively Recruiting
98
VA Northeast Ohio Healthcare System Louis Stokes Cleveland VA Medical Center
Cleveland, Ohio, United States, 44106
Actively Recruiting
99
Kaiser Permanente Center for Health Research
Portland, Oregon, United States, 97227
Actively Recruiting
100
Capital Area Research, LLC
Camp Hill, Pennsylvania, United States, 17011
Actively Recruiting
101
DM Clinical Research - Philadelphia
Philadelphia, Pennsylvania, United States, 19107
Actively Recruiting
102
Walker Family Care
Little River, South Carolina, United States, 29566
Actively Recruiting
103
Trial Management Associates, LLC
Myrtle Beach, South Carolina, United States, 29572
Actively Recruiting
104
Trial Management Associates
Myrtle Beach, South Carolina, United States, 29572
Actively Recruiting
105
Velocity Clinical Research, Spartanburg
Spartanburg, South Carolina, United States, 29303
Actively Recruiting
106
New Phase Research and Development
Knoxville, Tennessee, United States, 37909
Actively Recruiting
107
Clinical Neuroscience Solutions Inc.
Memphis, Tennessee, United States, 38119
Actively Recruiting
108
The Vanderbilt Vaccine Research Program Clinic at The Village at Vanderbilt
Nashville, Tennessee, United States, 37212
Not Yet Recruiting
109
Vanderbilt Investigational Drug Service (IDS)
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
110
Vanderbilt University Medical Center
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
111
Vanderbilt Vaccine Research Program Laboratory
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
112
Vanderbilt Vaccine Research Program
Nashville, Tennessee, United States, 37232
Not Yet Recruiting
113
Family Health Watch - KeyPoint Clinical Research
Dallas, Texas, United States, 75237
Actively Recruiting
114
KeyPoint Clinical Research
Dallas, Texas, United States, 75240
Actively Recruiting
115
North Texas Infectious Diseases Consultants, P.A
Dallas, Texas, United States, 75246
Actively Recruiting
116
Cedar Health Research - Euless
Euless, Texas, United States, 76040
Actively Recruiting
117
Memorial Hermann Hospital - TMC
Houston, Texas, United States, 77030
Not Yet Recruiting
118
The University of Texas Health Science Center at Houston
Houston, Texas, United States, 77030
Not Yet Recruiting
119
UT Physicians
Houston, Texas, United States, 77030
Not Yet Recruiting
120
DM Clinical Research- Cyfair
Houston, Texas, United States, 77065
Actively Recruiting
121
Mercury Clinical Research - Santa Clara Family Clinic
Houston, Texas, United States, 77087
Actively Recruiting
122
Dynamed Clinical Research, LP d/b/a DM Clinical Research
Tomball, Texas, United States, 77375
Actively Recruiting
123
Northwest Houston Heart Center
Tomball, Texas, United States, 77375
Actively Recruiting
124
J. Lewis Research, Inc. / Foothill Family Clinic South
Salt Lake City, Utah, United States, 84121
Actively Recruiting
125
The University of Vermont Medical Center Inc.
Burlington, Vermont, United States, 05401
Not Yet Recruiting
126
UVM Larner College of Medicine MMG/VCT
Burlington, Vermont, United States, 05401
Not Yet Recruiting
127
Clinical Research Partners, LLC
Richmond, Virginia, United States, 23226
Not Yet Recruiting
128
Providence Regional Medical Center Everett
Everett, Washington, United States, 98201
Not Yet Recruiting
129
Kaiser Permanente Washington Health Research Institute (KPWHRI)
Seattle, Washington, United States, 98101
Not Yet Recruiting
130
University of Washington - Harborview Medical Center
Seattle, Washington, United States, 98104
Actively Recruiting
131
Clinica Del Niño Y La Madre
Mar del Plata, Buenos Aires, Argentina, 7600
Actively Recruiting
132
Fundación Huésped
Buenos Aires, Buenos Aires F.D., Argentina, 1427
Actively Recruiting
133
Equipo Ciencia
Buenos Aires, Buenos Aires F.D., Argentina, C1428BNF
Actively Recruiting
134
Clinica Privada del Sol S.A
Córdoba, Córdoba Province, Argentina, X5000IIH
Actively Recruiting
135
CDC Centro Médico
Lujan de Cuyo, Mendoza Province, Argentina, 5505
Not Yet Recruiting
136
Sanatorio Sagrado Corazón
Buenos Aires, Argentina, 1039
Actively Recruiting
137
Centro Medico Barrio Parque
Buenos Aires, Argentina, 1425
Actively Recruiting
138
Investigaciones Clínicas Salta (ICSAL)
Salta, Argentina, A4400
Not Yet Recruiting
139
Tokyo-Eki Center-building Clinic
Chuo-ku, Tokyo, Japan, 103-0027
Not Yet Recruiting
140
Newquay Health Centre
Newquay, Cornwall, United Kingdom, TR7 1RU
Actively Recruiting
141
Royal Devon & Exeter Hospital
Exeter, Devon, United Kingdom, EX2 5DW
Actively Recruiting
142
Knowle House Surgery
Plymouth, Devon, United Kingdom, PL5 3JB
Actively Recruiting
143
Brunel Medical Practice (St Marychurch)
Torquay, Devon, United Kingdom, TQ1 4QX
Not Yet Recruiting
144
Panthera Biopartners - Preston
Preston, England, United Kingdom, PR2 9QB
Actively Recruiting
145
Synexus Scotland Clinical Research Centre
Glasgow, Glasgow CITY, United Kingdom, ML4 3NJ
Not Yet Recruiting
146
Southampton General Hospital
Southampton, Hampshire, United Kingdom, SO16 6YD
Actively Recruiting
147
Layton Medical Centre
Blackpool, Lancashire, United Kingdom, FY3 7EN
Actively Recruiting
148
Panthera Biopartners - Manchester
Rochdale, Manchester, United Kingdom, OL11 4AU
Actively Recruiting
149
Panthera Clinic - York
York, North Yorkshire, United Kingdom, YO24 4LJ
Actively Recruiting
150
Lakeside Surgery
Corby, Northamptonshire, United Kingdom, NN17 2UR
Actively Recruiting
151
Ormeau Clinical Trials
Belfast, Northern Ireland, United Kingdom, BT2 8BG
Actively Recruiting
152
Cheadle Community Hospital
Cheadle, Staffordshire, United Kingdom, ST10 1NS
Actively Recruiting
153
Synexus Midlands Clinical Research Centre
Birmingham, WEST Midlands, United Kingdom, B15 2SQ
Not Yet Recruiting
154
North Wales Clinical Research Facility
Wrexham, Wrexham [wrecsam Gb-wrc], United Kingdom, LL13 7YP
Not Yet Recruiting
155
Panthera Biopartners - Glasgow
Glasgow, United Kingdom, G51 4RY
Actively Recruiting
156
Manchester Royal Infirmary
Manchester, United Kingdom, M13 9WU
Not Yet Recruiting
157
Synexus Manchester Clinical Research Centre
Manchester, United Kingdom, M15 6SE
Actively Recruiting
158
Panthera Biopartners - Sheffield
Sheffield, United Kingdom, S2 5FX
Actively Recruiting
Research Team
P
Pfizer CT.gov Call Center
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
PREVENTION
Number of Arms
2
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