The mpox vaccine induced an antibody response in adolescents aged 12 to 17 years that matched that in adults, suggesting the shot can be used to protect the highly susceptible group.
Bavarian Nordic’s mpox vaccine Jynneos is safe to use in adolescents and can induce an antibody response that matches its effect in adults, according to the interim findings of a study funded by the National Institutes of Health.
The results, which were unveiled Wednesday at the 2024 IDWeek conference in Los Angeles, come from a Phase II trial that administered Jynneos to more than 300 adolescents aged 12 to 17 years and compared the vaccine’s safety and efficacy to that in over 200 adults 18 to 50 years.
Data were sparse with the NIH only revealing that Jynneos “generated antibody levels in adolescents equivalent to those observed in adults” two weeks after the second dose. “The vaccine was well tolerated through study day 210,” according to the NIH, which pointed out that side effects arose at similar frequencies between study groups.
Mary Healy, associated professor of pediatrics infectious diseases at Baylor College of Medicine and who presented the study at IDWeek, called the results “an important milestone for people living in areas with mpox” while noting that the vaccine continues to be “an important solution” to protect vulnerable populations from the virus, particularly adolescents.
Wednesday’s findings come just days after the World Health Organization prequalified the use of Jynneos for adolescents aged 12 to 17. According to the global health authority, this move will make the vaccine available for an age group of patients that are considered particularly vulnerable to the virus. The European Medicines Agency in September 2024 allowed the use of Jynneos in adolescents. The FDA has yet to grant a similar approval.
Adding to the NIH’s most recent data on Jynneos, several studies in recent months have helped improve the industry’s understanding of the vaccine, not just regarding its efficacy and safety but also the durability of its effects and acceptable dosing.
In April 2024, another NIH study found that even a dose-sparing regimen of Jynneos—where patients are given just one-fifths of its standard dose—can elicit an antibody response similar to that of the standard dose, though this effect waned much sooner. Earlier this month, another study showed that even at its approved dose, antibody titers appear to decline after six to 12 months, raising concerns about weakening protective immunity in patients that were vaccinated in during the 2022 outbreak.
In August 2024, the WHO declared the mpox outbreak a public health emergency of international concern. Though cases were largely concentrated in the Democratic Republic of Congo and in Africa at the time, WHO Director-General Tedros Adhanom Ghebreyesus flagged “the emergency of a new clade of mpox” which appears to be a more aggressive and deadlier version of the virus.
For Bavarian Nordic, the WHO’s declaration represents a promising windfall opportunity. In an August 2024 investor note, Jefferies analyst Peter Welford estimated that the company is looking at $600 million to $1 billion in revenue into 2025, if it can deliver its promised 10 million doses.
