Bavarian Nordic's Mpox Vaccine Effective for Teens and Adults Equally

A clinical trial conducted by the US National Institutes of Health (NIH) has demonstrated that Bavarian Nordic’s mpox vaccine triggers an antibody response in adolescents that is comparable to that observed in adults. The interim findings, which were unveiled at the Infectious Diseases Society of America’s IDWeek2024 conference in Los Angeles, could potentially facilitate the vaccine's broader application for individuals under 18 years old in the US and other regions where mpox cases have been reported.

An NIH spokesperson from the National Institute of Allergy and Infectious Diseases (NIAID) indicated that these interim results could support an application to expand the vaccine's licensure to include younger age groups. Currently, Bavarian Nordic's vaccine, marketed under the brand name Jynneos in the US, is only approved for adult use. However, an emergency use authorization was granted by the FDA during the 2022–2023 mpox outbreak, allowing the vaccine's use in adolescents for both pre- and post-exposure scenarios. Meanwhile, the European Medicines Agency (EMA) granted approval for MVA-BN’s use in adolescents in September.

Despite several countries approving the vaccine for adult mpox and smallpox prevention, the NIH noted in an October 16 press release that there is still insufficient data to support its licensure for those younger than 18 years.

The NIAID-sponsored Phase II study, identified as NCT05512949, was carried out in the US with participants aged 12 to 17 years. The study's results showed that antibody levels at day 43 post-vaccination were equivalent to those in adults aged 18 to 50 years. The frequency of adverse events was similar across the study groups, with the vaccine being well-tolerated up to day 210 of the study. Dizziness was more frequently reported among the adolescent group, a side effect that the NIH noted is common with various other vaccines administered to younger populations.

This mid-stage, randomized study included 229 healthy adolescents, including some with human immunodeficiency virus (HIV) infections. The Clade II mpox outbreak in Africa has particularly impacted individuals with compromised immune systems and pregnant women, with a significant number of those affected being under 18 years old.

Mpox cases have been on the rise in African regions over the past decade, and this year's reported cases have already surpassed the total count from the previous year. There have been over 24,000 confirmed or suspected cases of mpox, attributed to both Clade I and Clade II, with more than 600 resulting in fatalities.

Although the NIH study team affirmed the vaccine's safety and the robustness of the immune response in adolescents, they emphasized the necessity for further research in younger children. Bavarian Nordic is preparing to initiate its own Phase II clinical trial, NCT06549530, to evaluate the immunogenicity and safety of MVA-BN in children aged two to 12 years. This trial, partially funded by the Coalition for Epidemic Preparedness Innovations (CEPI), is scheduled to commence this month. The company has expressed its goal to expand the vaccine's indication to younger populations.

In an effort to combat the disease in Africa, Bavarian Nordic announced in September its intention to prioritize the production of two million mpox vaccines by the end of the year. The company has already dispatched 250,000 vaccine doses to the Democratic Republic of Congo, which is considered the epicenter of the outbreak.