The Food and Drug Administration on Friday authorized Pfizer’s and Moderna’s COVID-19 vaccines for children as young as 6 months old in a decision long awaited by parents, caregivers and doctors.
The FDA’s clearance comes two days after a panel of independent agency advisers unanimously supported the shots’ use in the youngest children, who until now have not been eligible for vaccination against COVID-19. A Centers for Disease Control and Prevention panel followed with a separate recommendation, which was endorsed by CDC Director Rochelle Walensky on Saturday.
“We understand that whenever a public health decision is made that involves children, there are strong opinions on both sides,” said FDA Commissioner Robert Califf in a press conference Friday. “But it’s important to know that while COVID-19 does affect older and immunocompromised populations more adversely than young children, young children can still suffer the severe consequences of COVID-19, including severe illness and death.”
Roughly 19 million children in the U.S. are under 5 and, despite their comparatively lower rates of COVID-19’s worst effects, they remain vulnerable to infection. Thousands of children under 5 have been hospitalized over the course of the pandemic and COVID-19 is now a leading cause of death in this age group, according to CDC data and information presented to the FDA’s advisers Wednesday. Other consequences of infection, such as an inflammatory syndrome known as MIS-C, can cause severe illness.
“Statistics like these are unnerving,” Califf said. “By vaccinating our youngest children, we hope to prevent the most devastating consequences of COVID and by extension provide benefits to their families and communities.”
Pfizer’s vaccine, which was developed in partnership with German drugmaker BioNTech, has been cleared for children over 5 since last October, but only about 30% of those between 5 and 11 years old are fully vaccinated. Moderna’s has only been authorized for adults, but on Friday the FDA also gave a green light to its use in older children and adolescents, too.
The authorizations follow several frustrating months of delays as both Pfizer and Moderna struggled to find a balance between lowering their vaccine’s dose to curb side effects and maintaining sufficient efficacy. Initial data from a two-dose series of Pfizer’s vaccine fell short of expectations, forcing the company to test a third dose and pushing back the FDA’s review by months.
Both Pfizer and Moderna primarily relied on a process known as “immunobridging,” which compares the immune response generated by vaccination in one group to levels known to be protective in others. In this case, the drugmakers compared immune responses in young children to those in older teenagers and young adults, and demonstrated they were equivalent.
Preliminary analyses also showed vaccination to be protective against COVID-19, although the small number of cases reported means the company’s estimates have a wide range of statistical possibilities.
“As with all vaccines for any population, when authorizing COVID-19 vaccines intended for pediatric age groups, the FDA ensures that our evaluation and analysis of the data is rigorous and thorough,” said Peter Marks, head of the FDA’s vaccine office, in a statement.
Importantly, neither Pfizer nor Moderna reported any cases of myocarditis, or heart inflammation, that is in very rare cases associated with the messenger RNA vaccines, particularly in older male adolescents. Other side effects were similar to what’s been observed in older age groups, but generally at lower rates.
Still, there are many uncertainties about the protection vaccines offer young children, especially against omicron and its related subvariants. It’s not clear whether the durability of their effectiveness might differ from adults, either. And in the case of Pfizer’s vaccine, the three-shot series may pose challenges, as data show substantially fewer people complete their full primary or booster vaccination regimen than get an initial dose.
Delilah Alvarado contributed reporting.
Editor’s note: This story has been updated to include mention of the CDC’s recommendation.