The results disclosed by Pfizer and BioNTech on Monday could support full approvals in the U.S. and elsewhere, which in turn could help bolster vaccination rates among adolescents and young teenagers. About 51% of 12- to 17-year-olds in the U.S. were fully vaccinated as of Nov. 21, the lowest of any age group aside from young kids who just became eligible this month, according to the Centers for Disease Control and Prevention.
Vaccination rates among U.S. adolescents spiked shortly after authorization in May but have plateaued since. Roughly 30% of parents polled by the Kaiser Family Foundation recently said they would “definitely not” get their kids in that age group vaccinated, the highest of any point since Pfizer’s shot became available.
Younger, healthier people are generally able to avoid the worst effects of COVID-19 better than those who are older or have weaker immune systems. Additionally, rates of a type of heart inflammation called myocarditis that’s been associated in rare cases with Pfizer’s and Moderna’s vaccines are greatest in teenage boys and young men.
But younger people can trigger outbreaks that close schools, cause parents to miss work or spread to more vulnerable adults. The risk-benefit calculation among adolescents may also change as infection rates, which have recently begun to climb, could increase further as people gather indoors and protection wanes for adults who haven’t yet been boosted.
The new results show Pfizer’s shot maintains strong protection through at least four months, even during the spread of the infectious delta variant. Efficacy results were collected through September, the two companies said. The side effect profile was “generally consistent” with what’s been seen so far in clinical testing, though Pfizer and BioNTech didn’t say whether any myocarditis was observed.
Still, though protection has held up through four months, it’s unclear whether 12- or 15-year-olds will also need a booster shot. Immunity against infection and mild COVID-19 seems to wane for adults after about six months, leading the U.S. and other countries to authorize additional doses for much of their adult population. The Health Ministry of Israel, which has relied on Pfizer and BioNTech’s vaccine, recently advised boosters for young teenagers based on a reported reduction in vaccine effectiveness in 16- to 19-year-olds.
Pfizer and BioNTech have the only vaccine available to 12- to 15-year-olds in the U.S., and likely will for some time. The FDA recently extended a review of Moderna’s vaccine in adolescents and young teenagers to better assess the risk of myocarditis, which appears to be more common with its vaccine than with Pfizer’s.