One-Dose MVA-BN Vaccine Moderately Effective Against Mpox

TUESDAY, Sept. 17, 2024 (HealthDay News) -- One dose of modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine is moderately effective against mpox infection in at-risk communities, according to a study published online Sept. 11 in The BMJ.

Christine Navarro, M.D., from Public Health Ontario in Toronto, and colleagues estimated the real-world effectiveness of the MVA-BN vaccine against mpox infection in an emulation of a target trial involving 9,803 men with a history of being tested for syphilis and a laboratory-confirmed bacterial sexually transmitted infection in the previous year or who filled a prescription for HIV pre-exposure prophylaxis in the previous year. Those who had been vaccinated 15 days previously were matched with unvaccinated men in a 1:1 ratio on each day between June 12 and Oct. 27, 2022. A total of 3,204 men who received the vaccine were matched with 3,204 unvaccinated controls.

The researchers identified 71 mpox infections, with 0.09 and 0.20 per 1,000 person-days in the vaccinated and unvaccinated groups, respectively, during the study period of 153 days. For one dose of MVA-BN, the estimated vaccine effectiveness against mpox infection was 58 percent.

"Our findings strengthen the evidence that MVA-BN is effective at preventing mpox infection and should be made available and accessible to communities at risk," the authors write.

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