Children ages 12 to 15 are now eligible for Covid-19 booster shots, a decision that the FDA is basing on the results of a study that was not conducted in the U.S. and did not even study the effects of boosting in children. The change is based on an analysis in Israel, where the vaccine was studied in adults 50 and older.
Under Monday’s expansion of the emergency authorization for the Pfizer and BioNTech vaccine, children 12 to 15 may receive a booster five months after receiving the second of two shots from the primary vaccination series. The five-month interval comes from analysis of the Pfizer vaccine’s efficacy in Israel, where the rise of cases last summer prompted officials there to approve a third dose to cope with the delta variant. The study covered people 50 and older who had received two shots at least five months earlier.
Of the 843,208 people in the study, 758,118 received a booster of the Pfizer vaccine. According to results published late last month in the New England Journal of Medicine, there were 65 deaths in the booster group compared with 137 deaths in the unboosted. The results showed that those who received a booster at least five months after a second dose of the Pfizer vaccine had 90% lower mortality from Covid-19 compared to those unboosted. The vast majority of participants in the study were 65 and older. The deaths reported in the study, for both the boosted and unboosted, were predominantly in that older group. Authors of the published research note that limitations of the study include its relatively short 54-day duration and the lack of availability of adverse event data.
Other regulators are implementing Covid-19 booster shots, and the time interval between the primary series of shots and the booster varies from country to country. The United Kingdom permits boosters at the three-month mark or later following the second dose of a two-shot vaccine regimen. According to National Health Service guidelines, the booster shots will be either the Pfizer or Moderna; for those who can’t receive either of those mRNA vaccines, the booster may be a shot of the AstraZeneca vaccine.
Speaking on a conference call with reporters on Monday, Janet Woodcock, the FDA’s acting commissioner, said the agency makes its decisions based on the data it has from the vaccine makers.
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“We have data down to five months that we can reliably project what is going to happen in the larger population,” she said. “Hopefully we will get real world data from the U.K. and we can see what that shows. As [Peter Marks, director of the Center for Biologics Evaluation and Research] just said, some of the benefit/risk considerations may mitigate against giving out an earlier boost. We don’t know that until we get the data. Right now, the action we’re taking is based on the information that we have.”
The risk/benefit Woodcock referenced is myocarditis, an inflammation of the heart that is a rare side effect of the Pfizer and BioNTech vaccine observed in some patients, mainly males. Marks said that the myocarditis risk appears to peak in those age 16 and 17, and that 98% of the reported cases were mild, leading to one-day hospitalizations treatable with non-steroidal anti-inflammatory drugs or acetaminophen.
“We’re not seeing long-lasting effects,” Marks said. “That’s not to say that we don’t care about this and that it’s not important, but what it’s to say is that in the setting of a tremendous number of omicron and delta cases in this country, the potential benefits of getting vaccinated in this age range outweigh that risk.”
The Pfizer and BioNTech vaccine is the only one that has secured full FDA approval so far. The approval covers those 16 and older. Emergency authorization was granted for children 12 to 15 last May; in October, the agency expanded the authorization to kids ages 5 to 11. The Monday decision to expand the authorization of booster shots to those in the 12 to 15 age group comes about six weeks after the agency broadly authorized boosters for anyone 18 and older at least six months following the second shot of a messenger RNA vaccine.
The five-month interval for boosters for kids 12-15 covers only those who received the Pfizer vaccine as their primary vaccination. For those who received shots of the other authorized vaccines, the boosting schedule remains unchanged: two months following Johnson & Johnson’s single shot-vaccine and six months following the two-shot regimen of Moderna’s vaccine. But the November decision on boosters permitted mixing and matching so those who received Moderna or J&J shots for their primary vaccination may receive a Pfizer vaccine as a booster.
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