ABOUT THIS STUDY
FOR MORE INFORMATION
Contact a representative by phone, email, or visiting the study website. Please see the references below:
Pfizer Clinical Trials Contact Center
1-800-718-1021
- Evidence of a personally signed and dated informed consent document.
- Willing and able to comply with study procedures.
- Subjects with an increased risk of future contact with healthcare systems or subjects who have received systemic antibiotics in the previous 12 weeks.
- Ability to be contacted by telephone during study participation.
- Negative urine pregnancy test for female subjects of childbearing potential.
- Investigator site staff members directly involved in the conduct of the study and
their family members, site staff members otherwise supervised by the investigator, or
subjects who are Pfizer employees, including their family members, directly involved
in the conduct of the study.
- Participation in other studies involving investigational drug(s)/vaccine(s) within 28
days prior to study entry until 1 month after the third vaccination.
- Previous administration of an investigational C difficile vaccine or C difficile mAb
therapy.
- Prior episode of CDI..
- Receipt of blood products or immunoglobulins within 6 months before enrollment.
- Subjects who may be unable to respond to vaccination due to:
- Metastatic malignancy; or
- End-stage renal disease; or
- Any serious medical disorder likely to be fatal within the next 12 months; or
- Congenital or acquired immunodeficiency; or
- Receipt of high dose systemic corticosteroids for 14 days within 28 days of
enrollment; or
- Receipt of chronic systemic treatment with other known immunosuppressant
medications, or radiotherapy, within 6 months of enrollment.
- Known infection with human immunodeficiency virus (HIV).
- Any bleeding disorder or anticoagulant therapy that would contraindicate intramuscular
injection.
- Any contraindication to vaccination or vaccine components, including previous
anaphylactic reaction to any vaccine or vaccine-related components.
- Prior small- or large-bowel resection.
- Any condition or treatment resulting in frequent diarrhea.
- Other acute or chronic condition or abnormality that may increase the risk associated
with study participation or IP administration or may interfere with interpretation of
study results
- Pregnant or breastfeeding female subjects; male subjects and female subjects who are
sexually active and at risk for pregnancy and will not/cannot use 2 methods of
contraception
NEED INFO?
Questions about a trial? Call or email to reach a Pfizer Clinical Trial Contact Center Representative

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Descriptive Information | |||||||
---|---|---|---|---|---|---|---|
Brief Title ICMJE | Clostridium Difficile Vaccine Efficacy Trial | ||||||
Official Title ICMJE | A PHASE 3, PLACEBO-CONTROLLED, RANDOMIZED, OBSERVER-BLINDED STUDY TO EVALUATE THE EFFICACY, SAFETY, AND TOLERABILITY OF A CLOSTRIDIUM DIFFICILE VACCINE IN ADULTS 50 YEARS OF AGE AND OLDER | ||||||
Brief Summary | The Clover trial is evaluating an investigational vaccine that may help to prevent Clostridium difficile infection. Participants in the study are adults 50 years of age and older, who are at risk of developing Clostridium difficile infection. The study will assess whether the vaccine prevents the disease, and whether it is safe and well tolerated. Each subject will receive 3 doses of Clostridium difficile vaccine or placebo and be followed for up to 3 years after vaccination for potential Clostridium difficile infection. | ||||||
Detailed Description | Not Provided | ||||||
Study Type ICMJE | Interventional | ||||||
Study Phase ICMJE | Phase 3 | ||||||
Study Design ICMJE | Allocation: Randomized Intervention Model: Parallel Assignment Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) Primary Purpose: Prevention | ||||||
Condition ICMJE | Clostridium Difficile Infection | ||||||
Intervention ICMJE |
| ||||||
Study Arms ICMJE |
| ||||||
Publications * | Not Provided | ||||||
* Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline. | |||||||
Recruitment Information | |||||||
Recruitment Status ICMJE | Active, not recruiting | ||||||
Actual Enrollment ICMJE | 17525 | ||||||
Original Estimated Enrollment ICMJE | 15776 | ||||||
Estimated Study Completion Date ICMJE | September 7, 2021 | ||||||
Estimated Primary Completion Date | September 7, 2021 (Final data collection date for primary outcome measure) | ||||||
Eligibility Criteria ICMJE | Inclusion Criteria:
Exclusion Criteria:
| ||||||
Sex/Gender ICMJE |
| ||||||
Ages ICMJE | 50 Years and older (Adult, Older Adult) | ||||||
Accepts Healthy Volunteers ICMJE | Yes | ||||||
Contacts ICMJE | Contact information is only displayed when the study is recruiting subjects | ||||||
Listed Location Countries ICMJE | Argentina, Australia, Belgium, Bulgaria, Canada, Chile, Colombia, Czechia, Finland, France, Germany, Hungary, Japan, Korea, Republic of, Peru, Poland, Portugal, Slovakia, Spain, Sweden, Taiwan, United Kingdom, United States | ||||||
Removed Location Countries | |||||||
Administrative Information | |||||||
NCT Number ICMJE | NCT03090191 | ||||||
Other Study ID Numbers ICMJE | B5091007 2016-003866-14 ( EudraCT Number ) CLOVER ( Other Identifier: Alias Study Number ) | ||||||
Has Data Monitoring Committee | Yes | ||||||
U.S. FDA-regulated Product |
| ||||||
IPD Sharing Statement ICMJE |
| ||||||
Responsible Party | Pfizer | ||||||
Study Sponsor ICMJE | Pfizer | ||||||
Collaborators ICMJE | Not Provided | ||||||
Investigators ICMJE |
| ||||||
PRS Account | Pfizer | ||||||
Verification Date | April 2021 | ||||||
ICMJE Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP |