Mpox Vaccination 84% Effective For Most People

Since the Mpox virus swept around the world in May 2022, Germany's Standing Commission on Vaccination has recommended that people at an elevated risk of infection receive a preventive vaccination.

After millions of JYNNEOS® (MVA-BN®, IMVAMUNE®) doses were administered, an observational study published positive effectiveness data today.

The Lancet Infectious Diseases published results from a study conducted at Charité – Universitätsmedizin Berlin on March 18, 2025, that found one dose of the JYNNEOS was 84% in people without HIV and 58% effective against mpox infection overall.

However, due to the significant drop in Mpox infections in the second half of 2022, the study could not determine the additional effect of a second vaccine dose.

Furthermore, Breakthrough infections were associated with reduced symptoms, compared with infections in unvaccinated individuals. 

In a related press release, Prof. Leif Erik Sander, Director of the Department of Infectious Diseases and Critical Care Medicine at Charité and a research group leader at the Berlin Institute of Health at Charité, stated, "Our results confirm that a single dose of the vaccine provides good protection against Mpox, at least for a short time."

"That is a very good figure, which is likely increased further by the second vaccine dose."

"The reason is that developing immune protection after vaccination presumably requires specific immune cells called T cells. These T cells often appear at lower levels in people with HIV and are not fully functional, which translates to a weaker immune response. This also corresponds to our observation that these participants experienced fewer local and systemic side effects after receiving the vaccine."

"We assume that people living with HIV develop protection against Mpox after the second vaccine dose, and urgently advise these people to receive the two vaccine doses." 

"The immune system typically develops longer-lasting immune protection when exposed to the vaccine on more than one occasion."

Further studies will be required to determine the precise extent of the protective effect in different groups following two vaccine doses.

As of March 29, 2025, the JYNNEOS vaccine is commercially available at many clinics and pharmacies in the United States.