A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older

Condition(s) studied

Investigational drug(s) / intervention(s)

C.difficile vaccine: C.difficile vaccine given as an intramuscular injection

Saline Placebo: 0.9% sodium chloride solution given as a intramuscular injection

Study summary

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 does not work. 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 clinic 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.

Eligibility

Primary outcome measure(s)

• The percentage of participants reporting local reactions — For 7 days after each vaccination
  Injection site pain, redness, and swelling as self-reported in electronic diaries
• The percentage of participants reporting systemic events — For 7 days after each vaccination
  Fever, vomiting, fatigue, headache, muscle pain, and joint pain as self-reported in electronic diaries
• Percentage of participants reporting adverse events — From each vaccination through 1 month after each vaccination
  As elicited by investigator site staff
• Percentage of participants reporting serious adverse events — From Vaccination 1 (Day 1) through 12 months after Vaccination 2 (last dose) (18 months)
  As elicited by investigator site staff
• The incidence of the first episode of medically attended and clinically meaningful primary Clostridioides difficile infection (CDI) — from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
  First episode of medically attended and clinically meaningful primary CDI incidence per 1000 person- years of follow- up
• The incidence of the first episode of medically attended primary CDI — from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
  First episode of medically attended primary CDI incidence per 1000 person- years of follow- up
• The incidence of the first episode of clinically meaningful primary CDI — from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)
  First episode of clinically meaningful primary CDI incidence per 1000 person- years of follow- up

Trial sites (185)

+ 145 more sites — see the full list on the official registry below.

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