US health officials announced on Friday that they are postponing their deliberations on the emergency authorization of Pfizer’s anti-COVID vaccine for children six months to 4 years old, in order to await more complete data on three doses.
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The move is expected to postpone by at least several weeks the potential authorization of a first vaccine for this age group, which includes 18 million children in the United States.
A meeting of a committee of experts had been convened for next Tuesday, but it was to decide on the authorization of two doses only.
In this context, Pfizer had transmitted the first results of its clinical trials to the American Medicines Agency (FDA).
“The data we saw made us realize that we needed to see data on the third dose,” FDA official Peter Marks said at a press conference.
The American agency thus announced to “postpone” the meeting.
The Pfizer-BioNTech alliance also said in a statement that it had decided to “wait for data on three doses,” with that number likely to provide “a higher level of protection for this age group.”
This data should be available “in early April”, the companies said.
For these very young children, a dose of only 3 micrograms per bite has been chosen by the pharmaceutical giant (compared to 30 for adults, and 10 for 5-11 year olds), in order to limit side effects.
But with this reduced dose, the immune response elicited in 2- to 4-year-olds was less strong than expected, Pfizer reported in December.
The company had thus announced that it wanted to test a third dose of vaccine for this age group, and had amended the protocol of its clinical trials in this direction.
But to everyone’s surprise, Pfizer announced at the beginning of the month that it had requested emergency authorization for its vaccine for a series of two doses, while specifying that it should have a total of three.
The company said it did so at the request of the FDA.
The idea of the American officials was to buy time, and that the parents could start the first two injections, while waiting for the potential authorization of the third, which must be injected at least two months after the second.
But some experts had openly criticized this highly unusual move.
Friday’s decision should thus be widely interpreted as a setback for the authorities’ strategy.