The European Medicines Authority has recommended extending the indication of the smallpox/mpox vaccine Imvanex (also know as Jynneos) to adolescents aged 12 to 17, the drug already being authorised in the EU to protect against smallpox, mpox and the disease caused by the vaccinia virus in adults.
Imvanex contains a live, highly weakened form of a virus called “modified vaccinia virus Ankara” (MVA-BN), which is related to the smallpox virus.
EMA’s human medicines committee (CHMP) based the recommendation to extend the use of Imvanex to adolescents on the interim results of a study that compared the vaccine’s ability to generate an immune response (produce virus-specific antibodies) in 315 adolescents and in 211 adults.
The researchers found the immune response in adolescents was similar to adults, so inferred the vaccine will provide similar protection in youngsters as that expected in adults.
The safety profile in younger people was also comparable to that seen in adults and no additional risk was identified.
As part of its recommendation, EMA has asked the marketing authorisation holder to submit the final results of the study by 30 May 2025 to further characterise the information about safety in adolescents.
The Agency’s assessment has important implications for the global response to the mpox outbreak in DRC and other countries, which was declared a public health emergency of international concern (PHEIC) by the WHO on 14 August 2024.
EMA is the regulatory agency of record for prequalification of this vaccine by WHO on 13 September 2024. This means that CHMP’s assessment constitutes the basis for WHO prequalification approval to facilitate timely and increased access to this vaccine in communities with urgent need.
Previously, EMA’s assessment was also taken into account by the national regulatory authority of the DRC in the fast-track approval of the vaccine. In addition, WHO has co-operated in EMA’s assessment of the extension of indication in adolescents, a population particularly vulnerable to mpox.
The current surge in cases in the DRC and several neighbouring countries is driven by the mpox clade I strain that is known to cause a more severe form of mpox in humans than the mpox clade II strain that spread during the 2022/2023 PHEIC. Mpox can be fatal for people with weak immune systems.
Imvanex protects against both the clade I and clade II mpox strains.
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One dose of smallpox jab cuts mpox risk – Canadian study
Monkeypox possibly linked to decrease in smallpox vaccine – global experts