Mpox vaccine efficacy wanes to ‘undetectable levels’ after 6-12 months: Study

New Delhi: Mpox continues to be a significant threat across the globe, amid the rising concerns, two studies have shown examined the efficacy of Bavarian Nordic’s vaccine against the fatal infectious disease wanes “to undetectable levels” in 6-12 months. Bavarian Nordic’s, the modified Vaccinia Ankara Nordic or MVA-BN is indicated for active immunisation against smallpox, Mpox and related orthopoxvirus infections and disease in all 18 years of age and more.
The World Health Organization (WHO), prequalifies the first vaccine that is administered as a two-dose injection given for 4 weeks. This is the first of such a study that is published in the open-access medical journal Eurosurveillance, which indicates that “orthopoxvirus-specific binding and MVA-neutralising antibodies disappear to undetectable levels one-year post-vaccination in at-risk people who received two doses of MVA-BN. The study has been led by researchers from the Erasmus University Medical Centre, in the Netherlands.
For conducting the study, the research team investigated 99 high-risk active, gay, bisexual or other men who have sex with men (GBMSM) and 19 laboratory workers in the Netherlands in 2022 and 2023. The participants of the study included both the ones who were born before and after 1974 when the smallpox vaccine ceased to be given in the Netherlands. According to the study, the antibodies given by the historic smallpox vaccination using first-generation vaccines can be identified for years.
During this process, the researchers found that there is rapid waning of antibodies in vaccine recipients without any pre-existing immunity. On the other hand, the other study published in the pre-print server and not peer-reviewed showed that the “MVA-BN vaccine generated pox serum antibody responses that disappeared after 6-12 months. Further, the study noted that antibody levels in the participants with two doses of the Mpox vaccine were comparable to or lower than peak antibody responses in people who received just one shot.