Immune Response to MVA-BN and Prior Smallpox Vaccination in People With HIV or at Risk for HIV Acquisition.

Little is known about the serologic response elicited by the Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccination (JYNNEOS) against mpox in elderly individuals with or without HIV. In this study, we measured levels of antibody against orthopoxvirus in selected participants (n = 114) with HIV or at risk for HIV acquisition from the Multicenter AIDS Cohort Study/Women's Interagency HIV Study Combined Cohort Study, who had no prior reported history of mpox. Participants reported MVA-BN vaccination history via questionnaires. The median age was 64 years, 24.6% were female, and 46% were HIV seropositive. Twenty out of 114 participants received at least 1 dose of MVA-BN. We found that MVA-BN induced sustained IgG levels regardless of HIV status, even up to 1 year. Birth before 1973 was correlated with higher IgG. MVA-BN-unvaccinated individuals with HIV had lower IgG than those without HIV. Although limited by small sample size, our study is among the first to assess anti-orthopoxvirus antibodies specifically in a vulnerable, older population and stratified by HIV status.