[Descriptive study of events allegedly attributable to mpox vaccination in Brazil in 2023]

This study describes the surveillance and safety actions of the mpox (Jynneos) vaccine in Brazil, from 2022 to 2023. A descriptive study of mpox cases and events supposedly attributable to vaccination and/or immunization for Jynneos vaccine, recorded in the information systems, was conducted. Absolute and relative frequencies and reporting coefficients of events supposedly attributable to vaccination and/or immunization per 1,000 administered doses were calculated. A total of 9,596 cases of mpox were registered and 49,000 doses of vaccine were distributed, of which 14,395 (31%) were administered and 65 events supposedly attributable to vaccination and/or immunization (4.5 per 1,000 administered doses) were notified. All events supposedly attributable to vaccination and/or immunization were non-serious, and 22 (33.8%) cases had product-related reactions. Results are within the expected frequency; however, the number of administered doses may not have been sufficient to detect rare or unusual events. Continued surveillance is necessary to ensure vaccination effectiveness and safety, especially among groups at higher risk for the disease.