New data pave way for wider use of mpox vaccine in adolescents, researchers say
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Key takeaways:
- Jynneos was safe and generated an antibody response in adolescents that was similar to that seen in adults.
- The new data could help expand the number of people eligible for the vaccine.
LOS ANGELES — Interim data from a phase 2 clinical trial of the Jynneos mpox vaccine showed that it is safe and generates an antibody response in adolescents that is similar to the response seen in adults, researchers reported.
Jynneos is approved by the FDA for use in adults and available to at-risk adolescents in the United States under an emergency use authorization. Earlier this year, it was made commercially available at pharmacies, physician offices and other facilities that normally vaccinate.
Mpox rates have surged again in Africa, prompting WHO to declare another global public health emergency — just 15 months after ending the emergency for the 2022 global outbreak.
According to C. Mary Healy, MD, and colleagues, children aged younger than 15 years account for 70% of cases and 88% of deaths in the current mpox outbreak in the Democratic Republic of the Congo (DRC).
“We know that mpox spreads through close personal contact, making household transmission important, and unfortunately, those who are likely to get sick are very often those in childhood and in younger age groups,” Healy, an associate professor of pediatric infectious diseases at the Baylor College of Medicine, said during a press briefing ahead of IDWeek, where the study data were presented. “The best way to prevent mpox is through vaccination.”
Healy and colleagues conducted an open-label multisite clinical trial at sites throughout the U.S. comparing the safety and immunogenicity of two subcutaneous doses of the vaccine administered to 315 adolescents aged 12 to 17 years with the vaccine responses of 211 adults aged 18 to 50 years.
According to the researchers, systemic and local events and adverse health events were relatively similar in both groups. Dizziness occurred in 3% of adolescents — similar to rates for other vaccines in this age group, Healy and colleagues said — but was not reported in adults.
By day 43, according to the researchers, geometric mean titers in adolescents (470.3 [95% CI, 422.3-523.8]) were noninferior to the response in adults (293.2 [95% CI, 249.8-344.2]) — a geometric mean titer ratio of 1.60 [95% CI, 1.32-1.95].
“The immune response to this vaccine was at least as good in the adolescents — and maybe even a little better than it is in adults,” Healy said. “These are very exciting results because they open the stage to possibly using this vaccine more widely on the global stage.”
According to C. Buddy Creech, MD, MPH, director of the Vanderbilt Vaccine Research Program at Vanderbilt University Medical Center, the European Medicines Agency approved the vaccine for adolescents aged 12 to 17 years in September, which has extended the number of people who can be vaccinated, including in endemic countries like the DRC.
“The important part of this work is ... establishing the safety and the immune response to this vaccine in a group that, up until now, did not have licensure to receive the vaccine,” Creech said during the briefing. “This is a really important step as we protect the most vulnerable among us.”
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Healy CM, et al. Abstract 579. Presented at: IDWeek; Oct. 16-19, 2024; Los Angeles.
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