A government-funded study on an mpox vaccine designed for adolescents has revealed that it is safe and produces an antibody response similar to that observed in adult populations, as per a scheduled interim review of the study’s findings. Adolescents are notably among those affected by the ongoing Clade I mpox outbreak.
A clinical trial, funded by the National Institutes of Health (NIH), examined the safety and immune response of an mpox vaccine in adolescents. This interim analysis indicated that the vaccine’s performance is comparable to that observed in adults. Adolescents are one of the groups impacted by the ongoing Clade I mpox outbreak. These interim trial results were shared at the IDWeek2024 conference held in Los Angeles.
The first documented case of mpox appeared in 1970 in the Democratic Republic of the Congo (DRC). Two strains of the virus triggering mpox have been recognized. Clade I, typically found in Central Africa, can lead to severe health complications. In contrast, Clade II, which is more widespread in West Africa, initiated the global mpox outbreak that started in 2022, typically causing milder symptoms. Individuals with weakened immune systems, children, and pregnant women are particularly at risk for severe cases of mpox, regardless of the virus strain. A significant portion of those affected in the current Clade I outbreak in DRC and other African nations consists of adolescents and children. The modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine is authorized in several countries for preventing mpox and smallpox in adults, but there is currently inadequate data to support its approval for individuals under 18 years old.
The NIH’s National Institute of Allergy and Infectious Diseases (NIAID) is overseeing a mid-stage study in the U.S. to assess the safety and immune response to two doses of the MVA-BN vaccine in adolescents aged 12 to 17, comparing results with those from adults aged 18 to 50. In a planned interim assessment, researchers measured antibody levels two weeks after the second dose (study day 43) and tracked safety for 180 days following the second dose (study day 210). Results indicated that the MVA-BN vaccine prompted antibody responses in adolescents on par with those of adults by day 43, and the vaccine was well tolerated through day 210. The overall occurrence of adverse events was similar between the two groups, though reports of dizziness were more frequent among adolescents compared to adults. However, this rate was akin to that seen with other vaccines given to adolescents.
The research team concluded that the interim results confirm the safety and immune response quality of the MVA-BN vaccine in adolescents, which is applicable to the U.S. and other regions with mpox cases. The authors emphasized the importance of assessing the MVA-BN vaccine in younger children to broaden the evidence available for all groups affected by mpox.
The NIH extends its gratitude to the research sites and volunteers involved in studies aimed at enhancing the response to mpox.
For additional details regarding this study, please visit ClinicalTrials.gov and search with the identifier NCT05512949.
