Real-world safety data for MVA-BN: Increased frequency of syncope following intradermal administration for immunization against mpox disease.

Abstract

BACKGROUND: MVA-BN vaccine (Jynneos, Imvamune, Imvanex) was used widely in the 2022 mpox outbreak. This experience provides real-world evidence about the vaccine's safety, particularly regarding intradermal use. METHODS: Bavarian Nordic's global safety database was searched for all adverse events following immunization (AEFIs) with MVA-BN. AEFI numbers were compared among administration routes. Selected events and administered doses were graphed over the mpox outbreak period. RESULTS: A total of 9585 AEFIs have been reported. The rate of myocarditis or pericarditis was <1 per 100,000 doses administered. Eighty-nine cases of syncope, fainting, or loss of consciousness were reported. This number rose after the August 2022 US emergency use authorization for intradermal administration, as did the proportion of all syncope AEFIs reported following intradermal administration (78,7&#xa0;%). CONCLUSION: Real-world data from large-scale administration of MVA-BN has confirmed the vaccine's established safety profile when administered subcutaneously. Intradermal administration is likely associated with increased syncopal event frequency.