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NCT Number: NCT07282665

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

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.

Recruiting

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Key information

Conditions

Clostridioides Difficile Associated Disease

Age range

65 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Clinica Del Niño Y La Madre, Mar del Plata, Buenos Aires, Argentina

Loading trial locations.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Who Can Join the Study (Inclusion Criteria):

  • People with recent or future planned contact with healthcare systems or who have recently received antibiotics.

Who Cannot Join the Study (Exclusion Criteria):

  • 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.

Treatment and study plan

C.difficile vaccine

Biological

C.difficile vaccine given as an intramuscular injection

Saline Placebo

Other

0.9% sodium chloride solution given as a intramuscular injection

Primary outcomes

  1. The percentage of participants reporting local reactions

    Time frame: For 7 days after each vaccination

    Injection site pain, redness, and swelling as self-reported in electronic diaries

  2. The percentage of participants reporting systemic events

    Time frame: For 7 days after each vaccination

    Fever, vomiting, fatigue, headache, muscle pain, and joint pain as self-reported in electronic diaries

  3. Percentage of participants reporting adverse events

    Time frame: From each vaccination through 1 month after each vaccination

    As elicited by investigator site staff

  4. Percentage of participants reporting serious adverse events

    Time frame: From Vaccination 1 (Day 1) through 12 months after Vaccination 2 (last dose) (18 months)

    As elicited by investigator site staff

  5. The incidence of the first episode of medically attended and clinically meaningful primary Clostridioides difficile infection (CDI)

    Time frame: 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

  6. The incidence of the first episode of medically attended primary CDI

    Time frame: 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

  7. The incidence of the first episode of clinically meaningful primary CDI

    Time frame: 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

Secondary outcomes

  1. The incidence of antibiotic use in the treatment of a first episode of the primary CDI

    Time frame: from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)

    First episode of primary CDI with antibiotic use incidence per 1000 person- years of follow- up

  2. The incidence of severe primary CDI as defined by Infectious Diseases Society of America (IDSA)/ Society for Healthcare Epidemiology of America (SHEA)

    Time frame: from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)

    First episode of severe or fulminant primary CDI incidence per 1000 person- years of follow- up

  3. The incidence of a first episode of primary CDI (any severity)

    Time frame: from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)

    First episode of primary CDI incidence per 1000 person- years of follow- up

  4. The incidence of all CDI (primary and recurrent)

    Time frame: from 14 days after Vaccination 2 to the end of the surveillance period (up to approximately 3.5 years)

    Time to all C.difficile infection cases

Study contacts

Contact information is provided by the study sponsor or research team.

Pfizer CT.gov Call Center

CONTACT

[email protected]

1-800-718-1021

Sponsors and collaborators

Lead sponsor

Pfizer

Industry

Registry information

Official study title

A PHASE 3, PLACEBO-CONTROLLED, DOUBLE-BLINDED, RANDOMIZED STUDY TO EVALUATE THE EFFICACY, SAFETY, AND TOLERABILITY OF A CLOSTRIDIOIDES DIFFICILE VACCINE IN ADULTS 65 YEARS OF AGE AND OLDER

Acronym: BEETHOVEN

Important dates

Study start
2025
Primary completion
2028
Study completion
2029
First posted
Dec 15, 2025
Registry last updated
May 26, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.