A Clinical Study Investigating the Safety and Immune Responses After Immunization With Investigational Monkeypox Vaccines

Substudy A was an open-label, dose-escalation, Phase I substudy to assess the reactogenicity, safety, and immunogenicity of up to three dose levels of the multivalent vaccine candidate BNT166a in 48 healthy participants with no prior history of known or suspected smallpox vaccination (vaccinia-naïve participants). Substudy B was a one group, open-label, Phase I substudy to assess the reactogenicity, safety and immunogenicity of the multivalent vaccine candidate BNT166a in 16 healthy participants with prior history of smallpox vaccination (vaccinia-experienced). Substudy D was a one group, open-label, Phase IIa substudy to assess the reactogenicity, safety, and immunogenicity of one dose level of BNT166a in \~32 healthy participants with no prior history of known or suspected smallpox vaccination (i.e., vaccinia-naïve participants). SSD was initiated after the interim analysis of SSA and SSB safety, reactogenicity, and immunogenicity data. The duration of study participation was \~ 14 months per participant in all of the substudies.