EMA Broadens Imvanex Vaccine Use to Teens as Mpox Cases Rise

The European Medicines Agency’s (EMA’s) Committee for Medicinal Products for Human Use (CHMP) has recommended extending the indication of the smallpox and mpox vaccine Imvanex to adolescents aged 12-17 years. 

The vaccine is already authorized in the European Union to protect against smallpox, mpox, and the disease caused by vaccinia virus in adults.

Mpox is a zoonotic disease primarily transmitted to humans through contact with animals, particularly rodents, but it can also spread via direct human-to-human contact. It is endemic in parts of Central and West Africa. 

The current rise in cases in the Democratic Republic of the Congo (DRC) and neighboring countries is driven by the mpox clade I strain, which is associated with more severe disease in humans compared with the mpox clade II strain responsible for the 2022-2023 public health emergency of international concern. Mpox can be fatal, especially in individuals with compromised immune systems.

Since mpox monitoring began in 2022, as of July 31, 2024, more than 100,000 confirmed cases have been reported across around 120 countries, along with over 200 fatalities associated with confirmed infections.

Safe and Effective in Adolescents

Data show that Imvanex provides protection against both clade I and clade II mpox strains.

The vaccine contains a live, highly weakened form of a virus called “modified vaccinia Ankara-Bavarian Nordic,” which is related to the smallpox virus. 

The CHMP based its recommendation to extend Imvanex’s use to adolescents on interim results from a study comparing the immune response (virus-specific antibody production) in 315 adolescents and 211 adults.

The immune response in adolescents was comparable to that in adults, suggesting that the vaccine will offer similar protection in both groups. According to the submitted data, the safety profile of Imvanex in adolescents was also consistent with that in adults, with no additional risks identified. As part of its recommendation, the EMA has requested the marketing authorization holder to submit final study results by May 30, 2025, to further clarify safety data in adolescents.

Decision Has Significant Implications

The CHMP’s assessment holds significant implications for the global response to the mpox outbreak in the DRC and other countries. The outbreak was declared a public health emergency of international concern by the World Health Organization (WHO) on August 14, 2024. The assessment also laid the groundwork for the WHO’s prequalification of the vaccine on September 13, 2024, aimed at improving access in communities facing urgent needs. 

The European Centre for Disease Prevention and Control has published advice for public health authorities on mpox to help public health professionals make informed decisions, reduce transmission, and address vaccine accessibility, especially in high-risk populations.