Sixteen-year-old Katelyn Evans of suburban Cincinnati rolled up the sleeve of her burgundy sweatshirt and waited for her shot — a chance to play a small role in combating the pandemic. The high school junior was among the first US teenagers younger than 18 to enter a clinical trial for a COVID-19 vaccine. And although she doesn’t know whether she received a placebo or an actual dose, she is helping build evidence for how adolescents respond to the Pfizer-BioNTech vaccine.
Until now, children have been mostly sidelined in the race for a vaccine. The path to pediatric vaccination will require a gradual expansion of large adult trials into teens and then into younger children, according to experts. Last week, Pfizer became the first manufacturer to gain US Food and Drug Administration (FDA) approval to test the vaccine in children as young as 12 years of age. Meanwhile, AstraZeneca, whose trial is paused in the United States, is already vaccinating 5- to 12-year-olds in clinical trials in the United Kingdom.
Still, debate continues to swirl around the timeline for US pediatric trials. Some pediatric vaccine experts are urging swift action, but the National Vaccine Advisory Committee (NVAC), which sends its recommendations to US Assistant Secretary of Health Brett Giroir, MD, is signaling that pediatric trials should await the release of safety and efficacy data from adult trials. The earliest such data will likely come from the Pfizer trial and could come as soon as late November, according to the company. (Based on current safety data in adult trials, Moderna intends to start pediatric trials by the end of the year, if it receives regulatory approval, a company spokesperson said.)
Stephen Hahn, MD, FDA commissioner, likewise indicated that the agency would want to see “really robust safety and efficacy data” in adults before moving forward with a pediatric vaccine trial. “Of course, we want to expedite the development of a vaccine for children, but we want to make sure that’s carefully done and thoughtfully considered,” he said during a recent webinar hosted by Michael Osterholm, PhD, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
How Heavy Is Their Burden of COVID-19?
When to start pediatric trials is a question that requires weighing the potential risks of novel vaccines against possible benefits. “The burden of disease in children is so low that I don’t think we can tolerate any adverse events in children,” said NVAC member H. Cody Meissner, MD, chief of pediatric infectious disease at Tufts Children’s Hospital, Boston, Massachusetts. Meissner is helping draft a panel recommendation that supports the “cautious but deliberate development” of phased trials.
Others look at the concept of burden more broadly. Since the pandemic began, 16-year-old Evans hasn’t been able to sing in the school choir. This fall, she returned to in-person classes, but in choir, they simply beat out the rhythm with their hands. Singing is considered a high-risk activity in the time of COVID-19.
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