Randomized Phase 3 Comparison of a 2-Dose and 3-Dose Regimen of a Detoxified Toxin A/B Clostridioides difficile Vaccine in Adults 50 Years and Older

Gretchen Crook; Erik Lamberth; Stephen Lockhart; Francine Lowry; Haiying Zhang; Yahong Peng; Kenneth Koury; Warren V. Kalina; Michael W. Pride; Annaliesa S. Anderson; William C. Gruber; Nicholas Kitchin

doi:10.1093/ofid/ofag219

April 15, 2026Open Forum Infectious DiseasesOpen Access

Randomized Phase 3 Comparison of a 2-Dose and 3-Dose Regimen of a Detoxified Toxin A/B Clostridioides difficile Vaccine in Adults 50 Years and Older

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Key Points

This trial aims to assess the immunogenicity and safety of 2-dose and 3-dose regimens of a Clostridioides difficile vaccine in older adults.
Phase 3 randomized trial with N=1994 participants aged 50 years and older
Compared immunogenicity and safety profiles of 2-dose and 3-dose regimens
Evaluated criteria for noninferiority for TcdA and TcdB immunogenicity.
Noninferiority for TcdA was met, but overall noninferiority criteria were not satisfied
Both vaccine regimens exhibited similar safety profiles
Risk of C difficile infection highlighted in the older population.

Implication

Randomized trial compares immunogenicity and safety of 2-dose versus 3-dose vaccine regimens in older adults, indicating differing immune responses.

Abstract

This phase 3 trial compared immunogenicity and safety of 2-dose versus 3-dose PF-06425090 Clostridioides difficile vaccine regimens in ≥50-year-olds (N=1994) at increased C difficile infection risk. Because TcdA but not TcdB immunogenicity noninferiority criteria were satisfied, the overall primary noninferiority objective was not met. Both regimens demonstrated similar safety profiles.

Discussion

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Cite This Study

Crook et al. (2026) studied this question.

synapsesocial.com/papers/6a0ea127be05d6e3efb5f966 https://doi.org/10.1093/ofid/ofag219

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Randomized Phase 3 Comparison of a 2-Dose and 3-Dose Regimen of a Detoxified Toxin A/B Clostridioides difficile Vaccine in Adults 50 Years and Older

Key Points

Implication

Abstract

Discussion

Cite This Study

Randomized Phase 3 Comparison of a 2-Dose and 3-Dose Regimen of a Detoxified Toxin A/B Clostridioides difficile Vaccine in Adults 50 Years and Older

Key Points

Implication

Abstract

Discussion

Cite This Study

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