Phase II Study of BNT166a mRNA Mpox Vaccine in Healthy Adults 18 to 64 Years in Africa Assessing Safety, Immune Response, and Side Effects Compared to Placebo

What this Trial Is About

Researchers are evaluating the safety, side effects, and immune response after one and two doses of the mRNA vaccine candidate BNT166a compared to a placebo in healthy adults. This randomized, double-blind, placebo-controlled Phase II trial includes two groups adults aged 18 to 45 years who have never had Orthopoxvirus exposure and adults aged 18 to 64 years who have previous Orthopoxvirus exposure. Participants receive two doses of BNT166a vaccine or placebo injections into the deltoid muscle, spaced at least 28 days apart. The study includes Cohort 1 Orthopoxvirus-nave adults 18-45 years and Cohort 2 Orthopoxvirus-experienced adults 18-64 years. The total study duration for each participant is approximately 14 months. During the study, participants will be closely monitored for local and systemic reactions for up to 7 days after each dose and for adverse events up to 14 months. Researchers will measure immune responses through antibody levels at baseline and one month after each dose. Safety assessments include tracking serious and medically attended adverse events, as well as any events causing withdrawal. Participants will have scheduled visits and assessments throughout the study to evaluate these outcomes.

A Randomized Clinical Trial Investigating the Safety, Reactogenicity, and Immunogenicity After Immunization With an mRNA-based Mpox Vaccine Candidate in Africa