Evaluation of Clinical Benefit and Safety Following CYFENDUS Administration for Post-Exposure Prophylaxis of Anthrax Disease.

The goal of this observational study is to evaluate the safety and clinical benefit of two doses of CYFENDUS vaccine when used with the concurrent recommended antibacterial regimen for post-exposure prophylaxis to prevent inhalational anthrax and/or anthrax meningitis.

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Key information

Conditions

Anthrax Bacillaceae Infections Bacterial Infections Bacterial Infections and Mycoses Cutaneous anthrax Gastrointestinal anthrax Gram-Positive Bacterial Infections Infections Inhalation anthrax

Sex eligibility

All sexes

Study type

Observational

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

Individuals who received any dose of CYFENDUS vaccine (with or without concurrent recommended antibacterial regimen) for anthrax post exposure prophylaxis during an identified mass B. anthracis exposure event in the United States.

Exclusion criteria

Individuals who did not receive CYFENDUS for anthrax post exposure prophylaxis during an identified mass B. anthracis exposure event in the United States.

Treatment and study plan

CYFENDUS

Biological

Intramuscular administration of two doses of Anthrax Vaccine Adsorbed, Adjuvanted

Primary outcomes

Number of individuals who developed inhalational anthrax and/or anthrax meningitis and received CYFENDUS for post exposure prophylaxis divided by the total number reported to have received CYFENDUS for post exposure prophylaxis.

Time frame: At least 12 months after containment of the mass exposure event

Sponsors and collaborators

Lead sponsor

Emergent BioSolutions

Industry

Registry information

Official study title

A Phase 4 Retrospective Observational Study of CYFENDUS™ Anthrax Vaccine Among Individuals Who Received Post-Exposure Prophylaxis Vaccination During a Bacillus Anthracis Mass Exposure Event

Important dates

Study start: 2035
Primary completion: 2036
Study completion: 2037
First posted: Dec 8, 2025
Registry last updated: Dec 8, 2025

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.

Published trials that share one or more normalized conditions with this study.

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