A study to assess whether a vaccine against Clostridium difficile prevents the disease, and whether it is safe and well tolerated when given to adults 50 years of age and older

INTERVENTION: Product Code: PF‐06425090 Pharmaceutical Form: Powder and suspension for suspension for injection INN or Proposed INN: N/A CAS Number: N/A Current Sponsor code: CLOSTRIDIUM DIFFICILE TOXOID (A AND B) Other descriptive name: PF‐06425090 Concentration unit: µg microgram(s) Concentration type: equal Concentration number: 200‐ Pharmaceutical form of the placebo: Solution for injection Route of administration of the placebo: Intramuscular use CONDITION: Primary C difficile infection (CDI) ; MedDRA version: 20.0 Level: PT Classification code 10054236 Term: Clostridium difficile infection System Organ Class: 10021881 ‐ Infections and infestations ; MedDRA version: 20.0 Level: LLT Classification code 10012748 Term: Diarrhoea, Clostridium difficile System Organ Class: 10021881 ‐ Infections and infestations Therapeutic area: Diseases [C] ‐ Bacterial Infections and Mycoses [C01] SECONDARY OUTCOME: Secondary end point(s): •CDI incidence per 1000 person‐years of follow‐up; •Mean time to resolution of diarrhea in first primary episodes of CDI ; •Proportion of subjects experiencing a first primary episode of CDI who have a non–protocol‐related medically attended visit during the CDI episode.; •Mean ATLAS score (based upon age, treatment with systemic antibiotics during CDI therapy, leukocyte count, serum albumin, and serum creatinine).; ; ; Timepoint(s) of evaluation of this end point: CDI incidence per 1000 person‐years of follow‐up is assessed during 2 time periods:; ‐ After receipt of the third dose of investigational product onwards.; ‐ After receipt of the second dose of investigational product onwards.; INCLUSION CRITERIA: Subjects must meet all of the following inclusion criteria to be eligible for enrollment into the study: 1.Evidence of a personally signed and dated ICD indicating that the subject has been informed of all pertinent aspects of the study. 2.Willing and able to comply with scheduled visits, vaccination plan, and other study procedures. 3.50 Years or older at enrollment. 4.Subjects with an increased risk of future contact with healthcare systems by virtue of: •At least 1 inpatient hospitalization =2 nights’ duration in the previous 12 months; or •At least 2 emergency room visits in the previous 12 months; or •At least 10 outpatient visits (primary and/or secondary care visits but excluding pharmacy and mental health visits) in the previous 12 months; or •Residence in a skilled nursing facility (a residential institution that provides professional nursing care and rehabilitation services, usually following discharge from the hospital); or PRIMARY OUTCOME: Main Objective: Primary Efficacy Objective: ; To demonstrate that Pfizer’s C difficile vaccine is effective in reducing the incidence of a first primary episode of CDI; ; Primary Safety Objective: ; To evaluate the safety profile of Pfizer’s C difficile vaccine as measured by the percentage of subjects reporting local reactions and systemic events, AEs, and SAEs. Primary end point(s): Primary Efficacy Endpoint: ; CDI incidence per 1000 person‐years of follow‐up; ; Primary Safety Endpoints: ; •Local reactions (pain, erythema, and induration); •Systemic events (fever, vomiting, headache, fatigue, new or worsening muscle pain, and new or worsening joint pain); •Nonserious AEs; •SAEs Secondary Objective: To evaluate the efficacy of Pfizer’s C difficile vaccine in reducing:; ‐ incidence of recurrent CDI ; To evaluate the efficacy of Pfizer’s C difficile vaccine in reducing:; ‐ The incidence of a first primary episode of CDI; ‐ The incidence of recurrent CDI ; In subjects who receive only 2 doses of vaccine, to evaluate the efficacy of Pfizer’s C difficile vaccine in reducing: ; ‐ the incidence of a first primary episode of CDI; ‐The incidence of recurrent CDI ; To evaluate the efficacy of Pfizer’s C difficile vaccine in reducing: ; ‐The incidence of all CDI cases ; To evaluate the efficacy of Pfizer’s C difficile vaccine in reducing the severity of CDI, defined by:; ‐The duration of CDI episodes.; ‐The requirement to seek medical attention.; ‐The ATLAS score; Timepoint(s) of evaluation of this end point: • CDI incidence per 1000 person‐years of follow‐up is assessed during up to 2 time periods :; ‐ After receipt of the third dose of investigational product onwards.; ‐ After receipt of the second dose of investigational product onwards.; ; • Local reactions: for up to 7 days following each dose of investigational product.; •Systemic events: for up to 7 days following each dose of investigational product.; •Nonserious AEs: from the signing of the informed consent document (ICD) to 1 month after receipt of the third dose of investigational product.; •SAEs: from the signing of the ICD to 6 months after receipt of third dose of investigational product.