Single and 2-dose vaccinations with modified vaccinia Ankara-Bavarian Nordic® induce durable B cell memory responses comparable to replicating smallpox vaccines.

This article focuses on the immunogenicity, durability, and booster effects of the modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine, approved for smallpox and monkeypox prevention. In clinical studies involving adults both naive and previously vaccinated against smallpox, primary MVA-BN vaccination induced immune responses that waned over two years but elicited rapid and robust anamnestic neutralizing antibody responses upon booster vaccination, comparable to boosting in those vaccinated decades earlier with older replicating smallpox vaccines. The vaccine demonstrated a favorable safety profile with mostly mild to moderate adverse events and no cardiac safety concerns. These findings support that MVA-BN induces durable immunological memory, which may provide effective protection against orthopoxviruses despite declining antibody titers over time.