A group of advisers to the Food and Drug Administration on Tuesday endorsed use of Pfizer's coronavirus vaccine in younger children, judging the benefits of the shot outweigh its safety risks in 5- to 11-year-olds.
But members of the committee, many of them vaccine and infectious disease experts, still grappled with limited data and uncertainty over how widely the vaccine should be given within that age group. Ultimately, after pressing both Pfizer and FDA staff, 17 advisers voted in support of its use, with one abstaining.
The vote likely paves the way for an emergency authorization from the FDA in the coming days, a high-stakes decision that would make about 28 million children eligible for vaccination. A separate committee of advisers to the Centers for Disease Control and Prevention is scheduled to meet next week, assuming a clearance is granted.
None of the three vaccines currently authorized in the U.S. are available for children under 12, hindering progress toward knocking down COVID-19 cases and risking disruption to school years.
While the meeting's outcome supports Pfizer's vaccine soon becoming the first, advisers voiced a range of concerns and debated whether a narrower authorization would be more appropriate than a broad clearance for all children between the ages of 5 and 11.
"This is a really tough one for me, but I do believe that children at highest risk do need to be vaccinated," said James Hildreth, CEO of Meharry Medical College in Tennessee and a committee member. "But vaccinating all of the children to achieve that just seems a bit much for me."
Others, while still cautious, noted the potential costs of limiting use more narrowly.
"When do you know enough? I think we certainly know that there are many children between 5 and 11 years of age who are susceptible to this disease [and] who could very well be sick and are hospitalized or die from it," said panelist Paul Offit, director of a vaccine center at the Children's Hospital of Philadelphia. "For me, I think I know enough to move forward."
Pfizer first disclosed study results indicating its vaccine was safe and spurred immune responses in young children last month. An official application for emergency authorization followed roughly two weeks later, setting up Tuesday's meeting to discuss the data in detail.
The drugmaker's case primarily relied on data showing the levels of coronavirus antibodies in young children after two, 10 microgram vaccine doses were almost identical to those reported in 16- to 25-year olds who received the currently authorized 30 microgram doses.
Data published by the FDA last Friday indicated the immune response translated to roughly 91% efficacy against symptomatic COVID-19, but the number of cases was relatively small, making the estimate more uncertain.
Advisers were less concerned about the vaccine's effectiveness than its safety, however, particularly as COVID-19 is considered to be less of a risk in younger children than in older adults.
Myocarditis, a type of heart inflammation that's been seen in rare cases with Pfizer's vaccine, was a focus of much of the day's discussion. The side effect, which is generally mild but can lead to hospitalization, is more common in adolescents and younger men. Panelists struggled to assess the risk of the side effect in children given Pfizer's trial was too small to detect it. Children are also going to receive a smaller dose of Pfizer's shot than teenagers or young adults, which could lower their risk.
"We're extrapolating — from higher risk boys and men in older age groups — a side effect from a higher dose vaccine," said Patrick Moore, a professor at the University of Pittsburgh Cancer Institute.
Presentations from the FDA showed that, in all but one very conservative scenario, the risk of hospitalization from COVID-19 outweighed the risk of hospitalization from myocarditis due to Pfizer's vaccine.
"We take measures to prevent influenza in children in order to prevent about 100 deaths a year from influenza," said Peter Marks, head of the FDA division that reviews vaccines, giving an example of the benefit-risk balance used to justify other common vaccines in children.
Tuesday's meeting, and the FDA's review, cap an extremely busy few months for the agency, during which it authorized booster doses for Pfizer's, Moderna's and Johnson & Johnson's vaccines for certain groups. Moderna could follow Pfizer soon, having announced earlier this week summary study results showing its vaccine to be safe and immunogenic in children.
More than 220 million people have received at least one coronavirus vaccine dose in the U.S., about two-thirds of the country's population and 78% of the people over 12 years old.