The FDA just authorized an extra Pfizer shot for children aged 5 to 11

• On Tuesday the FDA authorized a third COVID shot for kids aged 5-11.
• The Pfizer booster is set to be recommended any time from 5 to 9 months after youngsters' primary 2-dose series, but it will require a CDC recommendation.

On Tuesday the US Food and Drug Administration OK'd a third shot of Pfizer's COVID-19 vaccine for kids aged 5 to 11.

In a statement announcing the news, FDA Commissioner Robert Califf said "while it has largely been the case that COVID-19 tends to be less severe in children than adults, the Omicron wave has seen more kids getting sick with the disease and being hospitalized."

The FDA is authorizing the booster dose to be used in kids 5 and up who received their primary series of two shots at least five months ago. That is not a large share of kids in the US. As of last week, only 28% of 5 to 11 year olds nationwide had completed their primary COVID-19 vaccine series, according to data from the American Academy of Pediatrics.

In order for the boosters to go into arms, the move will also require a final Centers for Disease Control and Prevention recommendation, which will likely come following a key CDC advisory meeting this Wednesday.

In April, Pfizer announced that its third dose booster shot could significantly increase the levels of neutralizing antibodies kids had against the Omicron variant. That was according to a small study of 140 children aged 5 to 11 who got third shots.

However, larger real-world studies from the Centers for Disease Control and Prevention have suggested that youngsters' immune response to Pfizer's 2-shot series is still very decent at shielding kids from severe outcomes with COVID. Data from 14 US states the CDC released in April showed that during the Omicron outbreak, 87% of children aged 5 to 11 who were hospitalized were unvaccinated. Another study published in the New England Journal of Medicine in March found that vaccinated 5 to 11 year-olds reduced their risk of COVID hospitalization by two thirds.

"Where they see the difference is between the unvaccinated and vaccinated," epidemiologist Ruth Link-Gelles, who leads the CDC's COVID-19 vaccine effectiveness studies, told Stat.

Still, there have been some worries among disease researchers that the Pfizer dose which is administered to 5 to 11 year olds (which is 33% of the amount of vaccine that teens and adults get) may merit either a third dose boost, a longer interval between the first two doses, or both, in order to provide more enduring, robust, broad-spectrum disease protection to kids.

Shots for babies and toddlers should be 'ready for review' in June

The new booster recommendation still does nothing for babies and children under 5 in the US, who have no authorized COVID vaccine yet. The FDA has said it may be ready to authorize a COVID-19 vaccine for babies and toddlers 6 months and up from Pfizer, Moderna, or both companies by the end of June, but no firm timeline has been set yet, and the FDA is still waiting for completed applications from both vaccine makers.

"I fully expect that we'll have the data in June — or by June, ready for review," Dr. Peter Marks, who directs the center where vaccines are reviewed at the FDA, said on May 9 during a webinar for doctors, after he was asked when the agency might OK a shot for babies and toddlers.

"We're not going to hold anything back here because we really, we hear very much from parents how desperate they are," he said.