[Articles] Neutralising antibody responses to MPXV clades Ia, Ib, and IIb after infection or vaccination: a multicountry observational study

Historical or contemporary smallpox vaccination elicited little neutralising activity against various MPXV clades. It was found that previous MPXV clade IIb infection induced cross-reactive antibody binding, but only low-magnitude neutralising activity against clade Ib. These findings indicate important constraints in antibody-mediated immune responses across different viral clades. Although other immune mechanisms may contribute to protection, these results are crucial. They highlight the need for the development of new vaccines and antibody-based treatments. These new countermeasures should address the antigenic divergence among orthopoxviruses.