# To Understand the Safety and Effects of a C. Difficile Vaccine With New Adds-Ons That Will Be Given to Healthy Adults

> **NCT05805826** · PHASE1,PHASE2 · ACTIVE_NOT_RECRUITING · sponsor: **Pfizer** · enrollment: 936 (actual)

## Conditions studied

- Clostridoides Difficile Associated Disease

## Interventions

- **BIOLOGICAL:** C. difficile vaccine (previously studied formulation).
- **BIOLOGICAL:** C. difficile vaccine formulation 1.
- **BIOLOGICAL:** C. difficile vaccine formulation 2.
- **BIOLOGICAL:** C. difficile vaccine formulation 3.
- **OTHER:** Saline Placebo.

## Key facts

- **NCT ID:** NCT05805826
- **Lead sponsor:** Pfizer
- **Sponsor class:** INDUSTRY
- **Phase:** PHASE1,PHASE2
- **Study type:** INTERVENTIONAL
- **Status:** ACTIVE_NOT_RECRUITING
- **Start date:** 2023-03-23
- **Primary completion:** 2031-06-19
- **Final completion:** 2031-06-19
- **Target enrollment:** 936 (ACTUAL)
- **Last updated:** 2026-04-29


## Primary source

ClinicalTrials.gov registry: https://clinicaltrials.gov/study/NCT05805826

## Citation

> US National Library of Medicine, ClinicalTrials.gov registration NCT05805826, "To Understand the Safety and Effects of a C. Difficile Vaccine With New Adds-Ons That Will Be Given to Healthy Adults". Retrieved via AI Analytics 2026-06-25 from https://api.ai-analytics.org/clinical/NCT05805826. Licensed CC0.

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