The European Medicines Agency considered that Imvanex is effective at triggering the production of antibodies against smallpox to a level that provides protection at least as high as that from conventional smallpox vaccines. The vaccinia virus in Imvanex cannot replicate in human cells and hence is less likely to cause side effects than conventional smallpox vaccines. Imvanex would therefore be beneficial for people who cannot be given vaccines containing replicating viruses, such as patients with a weakened immune system.

For the prevention of monkeypox, the Agency considered that the effectiveness of Imvanex could be inferred from animal studies. In addition, because of the similarity between the virus in Imvanex (‘modified vaccinia virus Ankara’) and the variola (smallpox), monkeypox and vaccinia viruses, antibodies produced against it are expected to protect against monkeypox, smallpox as well as the disease caused by vaccinia. The safety profile of Imvanex is considered favourable, with vaccinated people experiencing mild to moderate side effects. The Agency therefore decided that Imvanex’s benefits are greater than its risks and it can be authorised for use in the EU.

Imvanex has been authorised under ‘exceptional circumstances’. This is because it has not been possible to obtain complete information about Imvanex due to the rarity of the diseases. Every year, the Agency will review any new information that becomes available and this overview will be updated as necessary.