Randomized Clinical Trial Investigating Safety, Reactogenicity & Immunogenicity After Immunization with mRNA-based Mpox Vaccine Candidate in Africa

Safety, Reactogenicity, and Immunogenicity of an Mpox mRNA Vaccine Candidate, BNT166a, in Healthy Participants Aged 18 Years and Older in African Countries: A Randomized, Double-blind, Placebo-controlled Phase II Trial

This Phase II trial will assess the safety, reactogenicity, and immunogenicity of BNT166a or placebo after one and two doses in healthy adults in African countries.

Visit the project overview on clinicaltrials.gov

BNT166a is being developed for a prophylactic indication. Reactogenicity, safety, and immunogenicity of BNT166a will be assessed in individuals who are Orthopoxvirus-naïve (non-primed, i.e., Cohort 1) and in individuals who are Orthopoxvirus-experienced (primed, i.e., Cohort 2). This trial will recruit healthy adults aged 18 to 64 years of age. All participants will receive two doses of BNT166a or placebo at least 28 days apart.

Consortium partners

  • Democratic Republic of the Congo
    • University of Kinshasa UNIKIN
    • Institute National de Recherche Biomedicale
  • South Africa
    • TASK Applied Science
    • TREAD Research Pty Ltd
    • Desmond Tutu Health Foundation Masiphumelele Clinic
    • Perinatal HIV Research Unit

Funders

  • Coalition for Epidemic Preparedness Innovations (CEPI)

Project duration

The planned study duration per participant is ~14 months. The study is currently (August 2026) recruiting.

Research are

Vaccination

Target population

This study will include the following cohorts:

  • Cohort 1: healthy adults aged 18 to 45 years inclusive, who are Orthopoxvirus-naïve.
  • Cohort 2: healthy adults aged 18 to 64 years inclusive, who are Orthopoxvirus-experienced.

 

Geographical scope

Africa (DRC; South Africa)

Study design

Clinical trial

Publications

Safety and immunogenicity of mRNA-based mpox vaccine candidate BNT166a: an open-label, dose-escalation, first-in-human trial
Bähner F, Faust S, Davies L et al. Safety and immunogenicity of mRNA-based mpox vaccine candidate BNT166a: an open-label, dose-escalation, first-in-human trial.
The Lancet Infectious Diseases, 2026; 0.