A Study To Investigate A Clostridium Difficile Vaccine In Healthy Adults Aged 50 To 85 Years, Who Will Each Receive 3 Doses Of Vaccine.

Study Overview
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Brief Summary
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This study will investigate a clostridium difficile vaccine in healthy adults aged 50 to 85 years, who will each receive 3 doses of vaccine. Subjects will receive their vaccine doses at either months 0, 1, and 3 or days 1, 8, and 30. Subjects will be divided into 2 age groups (50-64 and 65-85 years of age). The study will assess how safe and tolerable the vaccine is, and also look at subjects' immune response to the vaccine.

Official Title
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A Phase 1, Placebo-controlled, Randomized, Observer-blinded Trial To Evaluate The Safety, Tolerability, And Immunogenicity Of An Adjuvanted Clostridium Difficile Vaccine Administered As A 3-dose Regimen In Healthy Adults Aged 50 To 85 Years

Conditions
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Clostridium Difficile

Intervention / Treatment
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* Biological: C. difficile vaccine with adjuvant
* Biological: Placebo
* Biological: C. difficile vaccine with adjuvant
* Biological: placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy male and female adults aged 50 to 85 years at enrollment Exclusion Criteria: Proven or suspected prior episode of Clostridium difficile associated diarrhea. Unstable chronic medical condition or disease requiring significant change in therapy or hospitalization for worsening disease within 8 weeks before receipt of study vaccine. Any contraindication to vaccination or vaccine components, including previous anaphylactic reaction to any vaccine or vaccine-related components

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm Label: Month 0, 1 and 3 Schedule<br> | Biological: C. difficile vaccine with adjuvant<br>* C. difficile vaccine with adjuvant administered at Month 0, 1, and 3.<br>Biological: Placebo<br>* Placebo administered at Month 0, 1, and 3.<br>|
| Experimental: Day 1, 8, and 30 Schedule<br> | Biological: C. difficile vaccine with adjuvant<br>* C. difficile vaccine with adjuvant administered at day 1, 8, 30.<br>Biological: placebo<br>* Placebo administered at Day 1, 8, and 30.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of subjects reporting local reactions (pain, erythema, and induration) and their severity, as self reported on e-diaries. |  | 7 days after vaccination | 
| Proportion of subjects reporting systemic events (fever, vomiting, diarrhea, headache, fatigue, new or worsening muscle pain, and new or worsening joint pain) and their severity, as self reported on e-diaries. |  | 7 days after vaccination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of subjects in each vaccine group with neutralizing antibody levels (in Neut units/mL) greater than or equal to specified threshold(s). |  | Up to 12 months post-dose 3 | 
| Proportion of subjects in each vaccine group with neutralizing antibody levels, expressed as geometric mean concentrations (GMCs) (in Neut units/mL). |  | Up to 12 months post-dose 3 | 
| Proportion of subjects in each vaccine group with a greater than or equal to 4 and higher fold-rises in neutralizing antibody levels (in Neut units/mL). |  | Up to 12 months post-dose 3 |