The Public Health Agency of Sweden leads international study on mpox vaccine
An international study will investigate the effect of a third dose of vaccine against mpox. The EU-funded project involves researchers from universities and clinics in Sweden, Belgium, France, and Ireland, and is coordinated by the Public Health Agency of Sweden.
Mpox has been spreading in several parts of the world since 2022. Since 2024, a more severe virus variant has also begun to spread outside Africa, leading the World Health Organization (WHO) to declare it a public health emergency of international concern between August 2024 and September 2025.
The MVA-BN vaccine is currently used and provides strong protection against the disease, but newer data suggest that protection may wane over time. There is therefore a need to study whether a booster dose, in addition to the primary schedule, can provide stronger and longer-lasting immune response.
Different ways of vaccinating
The trial aims to compare the immune response and safety of a booster dose administered either intradermally (in the skin) or subcutaneously (under the skin). The results will provide important knowledge on which method offers the best immune response and for how long.
“With intradermal vaccination, only one fifth of the dose used for subcutaneous vaccination is needed. This means we can save valuable vaccine doses while at the same time investigating whether immune response remains just as strong. This is important knowledge for Sweden as well as for countries facing larger mpox outbreaks while having very limited access to vaccines,” says Deputy State Epidemiologist Klara Sondén.
International collaboration
The Public Health Agency of Sweden is leading the trial in close collaboration with Södersjukhuset (Stockholm South General Hospital) and Karolinska Institutet, as well as with researchers in Belgium, France and Ireland. The trial will run from 2025 to 2028 and will include around 640 adult participants across the four countries. Venhälsan at Södersjukhuset will be responsible for approximately half of the trial participants. Evaluation of the immune response to the booster dose will be carried out at the Public Health Agency’s laboratory in Sweden and at three laboratories in France.
“The results could be highly significant for future recommendations on mpox vaccination in Sweden, the EU and globally, particularly in situations with limited vaccine availability. We are especially pleased that the Public Health Agency of Sweden is coordinating the work in close collaboration with several academic institutions and internationally renowned researchers,” says Klara Sondén.
The European Commission is funding the study with EUR 4.9 million (approximately SEK 54 million) through an agreement signed by the Public Health Agency of Sweden with the European Health and Digital Executive Agency (HaDEA) under the EU4Health Programme.The project has also received financial support from the Swedish Ministry for Foreign Affairs to collaborate with the Africa Centres for Disease Control and Prevention (Africa CDC).
Partners
- AP-HP Assistance publique – Hôpitaux de Paris
- Institute of Tropical Medicine in Antwerp
- Karolinska institutet
- Södersjukhuset (Stockholm South General Hospital)
- University college Dublin
Affiliated research groups with laboratories
- ANRS MIE
- I-REIVAC network
Supporting organisation
- Africa CDC