Pro/con: vaccination and waning immunity - presents contrasting perspectives on the durability of vaccine-induced protection and the potential need for booster strategies.

PURPOSE OF REVIEW: mpox vaccination remains the only effective drug-based tool against mpox. Currently, there are two third-generation vaccines: LC16m8 and MVA-BN. Immunogenicity, observational and modelling data have demonstrated their efficacy in preventing mpox. However, evidence of waning immunity from 1 year after mpox vaccination has emerged, while mpox is still circulating worldwide, and there is a threat of a more contagious and virulent clade.

RECENT FINDINGS: We review the available data on immunogenicity of mpox vaccines, after primary and booster dose. There are pros and cons to recommending a booster dose. Immunogenicity data showed that an MVA-BN booster can effectively induce a humoral response, which is important for protective immunity. However, without a validated correlate of protection, clinical data are needed, and public policy considerations such as the limited numbers of doses available must be taken into account.

SUMMARY: Implementing a booster dose in guidelines requires a careful consideration of dose allocation globally, a better characterization of the burden of mpox, and clinical data on vaccine effectiveness to define vaccination objectives.