Smallpox is an infectious disease caused by the variola virus of the Orthopoxvirus genus. The last known naturally transmitted case occurred in Somalia in 1977, and in 1980 WHO declared smallpox eradicated.

In July 2022, a multi-country outbreak of mpox was declared a Public Health Emergency of International Concern (PHEIC) after the virus spread rapidly through sexual contact across countries where it had not previously been reported. The PHEIC was lifted in May 2023 following a sustained global decline in cases.

In August 2024, the WHO Director-General declared a new PHEIC in response to a resurgence of mpox in the Democratic Republic of the Congo and other African countries. The PHEIC was lifted in September 2025 after cases showed a sustained decline across the region.

There are two licensed vaccines available for use in response to the current mpox outbreak: MVA-BN and LC16m8. WHO published a position paper in August 2024 providing policy recommendations for their use, followed by interim guidance outlining operational considerations for MVA-BN and LC16m8 vaccines. MVA-BN is a non-replicating smallpox and mpox vaccine that has been prequalified by WHO in September 2024 (with age extension in October 2024). LC16m8 is a minimally replicating smallpox and mpox vaccine, which was granted WHO Emergency Use Listing (EUL) in November 2024.