The Food and Drug Administration (FDA) has approved the use of Pfizer’s Covid omicron booster as a fourth dose for children under 5 years of age.

An employee draws a syringe with Comirnaty vaccine from Biontech and Pfizer adapted to the Omicron-BA.1 variant at the Mainz vaccination center.

Sebastian Christoph Gallnow dpa | Photo Alliance | Getty Images

The U.S. Food and Drug Administration on Tuesday authorized pfizer Omicron booster for children under the age of five who have previously received three doses of the company’s original vaccine.

Children aged six months to four years who completed a three-dose primary series of original Pfizer and BioNTech monovalent vaccines more than two months ago are now eligible for one booster dose of the updated vaccine. The new shot is bivalent, meaning it targets the original Covid strain as well as omicron BA.4 and BA.5.

Pfizer’s primary series for young children is three doses, while rival drugmaker Moderna’s primary series for the same age group is only two doses.

From Decemberchildren in this age group who received two doses of the original Pfizer vaccine were eligible for a booster dose of omicron as the third dose or the last dose in their primary series. The agency noted that children who received the third dose of omicron are now not eligible for the bivalent booster, but they should still be protected from a severe case of Covid.

The new authorization is for young children who received three doses before the new vaccine became available.

“Today’s approval gives parents and guardians of children aged 6 months to 4 years who received a primary three-dose series of Pfizer-BioNTech monovalent COVID-19 vaccine the opportunity to upgrade their child’s protection by receiving a booster dose of Pfizer’s vaccine. BioNTech COVID-19 vaccine, bivalent,” Peter Marks, director of the FDA’s Center for Biological Evaluation and Research, said in a statement.

The agency’s decision aims to better protect young children after a terrible winter season when hospitals were overwhelmed with toddlers suffering from a variety of respiratory illnesses including Covid, RSV and the flu.

The FDA said the decision was based in part on clinical trial data from 60 children in an age group who had previously received three doses of Pfizer’s original vaccine and one dose of the company’s new booster dose. One month after the children received the booster dose of omicron, they demonstrated an immune response to both the original Covid strain and omicron BA.5 and BA.5.