Trial results indicate Jynneos vaccine performs well in young children
October 9, 2025
Bavarian Nordic’s announcement of positive trial results for its Jynneos (MVA-BN) mpox and smallpox vaccine in children marks a significant milestone in outbreak preparedness. Conducted in the Democratic Republic of the Congo and Uganda, the trial found that children aged 2 to 11 produced immune responses equal to or stronger than adults, with no new safety concerns. This finding is critical for regions where children are disproportionately affected by mpox. Pending regulatory approval, expanding vaccination eligibility to younger populations could strengthen disease prevention efforts and fill a crucial protection gap in global health security.
Bavarian Nordic’s recent clinical trial results for its Jynneos (MVA-BN) mpox and smallpox vaccine represent a major advancement in protecting one of the most vulnerable populations: children. The Phase 3 trial, conducted in the Democratic Republic of the Congo and Uganda, evaluated 227 children aged 2 to 11 and 224 adults aged 18 to 50. Two weeks after receiving their second dose, children exhibited immune responses comparable to or exceeding those of adults, with the youngest group (ages 2 to 5) demonstrating 2.5 times higher antibody levels. Importantly, the vaccine was well tolerated and showed no unexpected safety concerns.
The study was jointly funded by Bavarian Nordic and the Coalition for Epidemic Preparedness Innovations (CEPI). Both partners emphasized that these findings bring the global community one step closer to authorizing the vaccine for use in children. Paul Chaplin, President and CEO of Bavarian Nordic, highlighted that while vaccination efforts against mpox are improving across Africa, young children remain especially susceptible to infection and severe disease.
Jynneos is currently approved for individuals aged 12 and older in multiple regions, including the United States and the European Union. Bavarian Nordic intends to submit final pediatric trial data to the European Medicines Agency in 2026 to expand its indication to children aged 2 and above.
This development has the potential to transform outbreak control strategies in regions where mpox remains endemic. Children in sub-Saharan Africa, often under-immunized and living in high-transmission settings, face significant risks from the virus. A safe and effective pediatric vaccine could help close a critical immunization gap and serve as a vital component of integrated mpox prevention efforts. If regulatory agencies confirm these promising findings, Jynneos could become a cornerstone of future pediatric outbreak preparedness and response worldwide.