The Food and Drug Administration on Tuesday authorized a booster dose of the Pfizer-BioNTech Covid-19 vaccine for children ages 5 to 11.
Children in the age group can get a booster shot at least five months after they’ve received the primary two-dose series, the FDA said in a statement.
The booster shot is 10 micrograms, the same dosage as the primary series for the age group and a third of the dosage given to people ages 12 and up.
The FDA’s decision will now go to the Centers for Disease Control and Prevention, which will make a recommendation about how the boosters should be used for the age group.
The CDC's independent group of advisers, known as the Advisory Committee on Immunization Practices, is expected to discuss the booster during a scheduled meeting Thursday. CDC Director Dr. Rochelle Walensky is expected to issue a final recommendation following that meeting. Shots could begin as early as Friday.
Less than a third of the 28 million 5 -to-11-year-old children in the United States have received two doses of a Covid vaccine, according to data from the CDC.
Dr. Peter Marks, the FDA's top vaccine regulator, noted Tuesday that parents can protect their children from "potentially severe consequences" of Covid by getting them vaccinated with the two-dose primary series.
Dr. Paul Offit, a vaccine expert at Children's Hospital of Philadelphia, said the booster dose should provide better protection against mild illness caused by omicron and its family of subvariants, which appear to be more adept than previous strains at sidestepping immunity from vaccinations or prior infection.
Clinical trial results released in April found a booster dose of the Pfizer vaccine in children 5-11 raised antibody levels against the original strain of the coronavirus as well as the omicron variant. The results did not show how long the antibodies remain elevated, though higher antibody levels from boosters in adults usually persist for about four months.
Offit said the additional dose in children should raise antibody levels enough to provide a high level of protection against mild disease for at least "a few months."
"What the third dose provides you is probably three to six months of better protection," he said.
The results came two months after researchers from the New York State Department of Health reported that two doses of the Pfizer vaccine offered little protection against infection in children 5 to 11, with the vaccine’s effectiveness falling to 12 percent in December and January.
The CDC later reported that two doses for children still protected strongly against severe outcomes of Covid, including hospitalization and death.
Two doses were very good at protecting against mild disease from the delta variant “but not very good against omicron,” Offit said.
The FDA has already authorized a third Pfizer dose for children 5-11 with compromised immune systems as part of their three-dose primary series.
Children under 5 are the only group in the U.S. who remain ineligible for the Covid vaccine, though that may soon change.
The FDA is currently reviewing Moderna's application for authorization of its two-dose vaccine for children ages 6 months to 5 years. A final decision is expected in June.
Pfizer has yet to submit its application to the FDA on a three-dose vaccine for kids under 5, but it is expected to do so in the coming weeks, Pfizer CEO Albert Bourla said this month.