The timeline on covid-19 vaccines for U.S. children under 5 years will be postponed yet again. On Friday, the Food and Drug Administration announced it would cancel a key meeting set for next week on the potential approval of Pfizer and BioNTech’s under-five vaccine, and that it would now wait for additional data concerning the impact of a third dose before any final decision. Pfizer has since said this data should be available by early April. The additional data the FDA seeks concerns the effectiveness of the vaccine in provoking a strong immune response, not its safety.
In early February, anonymous officials disclosed the administration’s plans to encourage and speed along Pfizer’s application for an emergency use authorization of its low-dose vaccine for children under five—one that would have seen the vaccine adopted as a two-dose series. Soon after, the FDA announced that an advisory committee meeting, intended to elicit the input of outside experts, would be scheduled for February 15, and it was expected that an authorization could arrive before the end of the month.
The move was surprising, since Pfizer’s preliminary data in December had suggested that two low-doses of the vaccine did not provoke a similarly strong immune response in children between the ages of 2 and 5 years as it had in older children and young adults (a strong response was seen in children ages six months to under 2 years). At the time, Pfizer announced that it would continue its trials by adding a third dose to the schedule. But the anonymous officials reportedly said that administration wanted to authorize the vaccine as-is sooner rather than later, with the hope that Pfizer’s ongoing research would support the later recommendation of a third dose.
While the decision was lauded by some experts, others were worried about the implications of authorizing a vaccine without clear data of its efficacy, even if the odds were very good that a third dose would make younger children better-protected (other research has regularly shown that a third dose enhances immunity in adults). The stage was set for a possibly contentious advisory meeting next week, but now it will not happen.
This afternoon, the FDA postponed the meeting. In its rationale, the agency explained that it had recently been notified by Pfizer of “additional findings from its ongoing clinical trial” and that these findings had apparently changed their minds about the plan.
“Based on the agency’s preliminary assessment, and to allow more time to evaluate additional data, we believe additional information regarding the ongoing evaluation of a third dose should be considered as part of our decision-making for potential authorization,” the FDA said in its statement explaining the postponement.
On Friday, Pfizer and BioNTech formally announced that they would pull back their application for a two-dose vaccine. In their statement, they said that the recent surge of pediatric infections, fueled by the Omicron variant, had allowed lots of trial data to be generated. And “given that the study is advancing at a rapid pace, the companies will wait for the three-dose data as Pfizer and BioNTech continue to believe it may provide a higher level of protection in this age group.”
As things stand now, the companies expect to have enough data ready to show in early April, after which they’ll once again file for an emergency use authorization.
Though the delay may be disheartening to many parents, at least some experts have already praised the move. Daily new cases in the U.S. appear to be substantially declining, lessening the risk of outbreaks among this age group. Should things go well, a covid-19 vaccine for the youngest kids may still be ready in case and before a new wave of illness arrives.