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

December 4, 2025 updated by: Emergent BioSolutions

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

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.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Estimated)

250

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The study population will include adults for which CYFENDUS is indicated (18 to 65 years of age), but it may include pediatric, pregnant, and geriatric populations if they are vaccinated with CYFENDUS based on public health recommendations as part of outbreak management.

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
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
At least 12 months after containment of the mass exposure event

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Emergent BioSolutions

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

November 1, 2035

Primary Completion (Estimated)

November 1, 2036

Study Completion (Estimated)

November 1, 2037

Study Registration Dates

First Submitted

November 24, 2025

First Submitted That Met QC Criteria

December 4, 2025

First Posted (Actual)

December 8, 2025

Study Record Updates

Last Update Posted (Actual)

December 8, 2025

Last Update Submitted That Met QC Criteria

December 4, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • EBS-AVA-213

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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