The Imvanex vaccine is already authorised in the European Union (EU) to protect adults against smallpox, mpox (formerly known as monkeypox) and vaccinia virus disease. It contains a highly weakened, live form of a virus known as “modified vaccinia virus Ankara” (MVA-BN), which is related to the smallpox virus.
Now, the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) has recommended extending the use of Imvanex to adolescents based on preliminary results of a study that compared the vaccine’s ability to generate an immune response (production of specific antibodies against the virus) in 315 adolescents and 211 adults.
The immune response in adolescents was similar to that in adults, suggesting that the vaccine will provide equivalent protection in both groups. The data presented indicate that the safety profile of Imvanex in adolescents is comparable to that observed in adults, with no additional risks identified. As part of its recommendation, the EMA has requested the marketing authorisation holder to submit the final results of the study by 30 May 2025, in order to obtain more information on safety in adolescents.
Vaccination helps curb the mpox outbreak
The Agency’s assessment has significant implications for the global response to the mpox outbreak in the Democratic Republic of the Congo (DRC) and other countries, which was declared a Public Health Emergency of International Concern (PHEIC) by the World Health Organization (WHO) on 14 August 2024.
“Although the overall risk of MPOX infection for the general EU population remains low, we are constantly working at EU level to ensure good preparedness,” said European Health Commissioner Stella Kyriakides in a statement reported by EFE Agency. “The fact that adolescents aged 12 to 17 can now be protected with a safe and effective vaccine is an important step forward,” she added.
Mpox can be fatal for people with weakened immune systems.
MPox is a disease transmitted to people primarily by animals, such as rodents, but can also spread between people through direct contact. It is endemic in some regions of Central and West Africa. The recent increase in cases in the DRC and several neighbouring countries is driven by the clade I strain of mpox, known to cause a more severe form of the disease in humans, compared to the clade II strain, which spread during the 2022/2023 PHEIC. MPox can be fatal for people with weakened immune systems.
The EMA is the regulatory agency that oversaw the WHO prequalification of this vaccine on 13 September 2024. This means that the CHMP assessment served as the basis for the WHO prequalification approval, facilitating rapid and broad access to the vaccine in communities that urgently need it.
Previously, the EMA assessment was also taken into account by the DRC national regulatory authority for the accelerated approval of the vaccine. In addition, WHO has collaborated with the EMA in assessing the extension of the indication in adolescents, a population particularly vulnerable to mpox. The data suggest that Imvanex protects against both clade I and clade II mpox strains.
