The omicron-fighting COVID-19 vaccine is now approved for children ages 6 months and older, the U.S. Food and Drug Administration said Thursday.

Children under age 5 previously weren’t permitted to receive the bivalent booster.

“We encourage parents and caregivers of those eligible to consider doing so — especially as we head into the holidays and winter months where more time will be spent indoors,” FDA Commissioner Robert M. Califf said Thursday.

“As this virus has changed, and immunity from previous COVID-19 vaccination wanes, the more people who keep up to date on COVID-19 vaccinations, the more benefit there will be for individuals, families and public health by helping prevent severe illnesses, hospitalizations, and deaths.”

The new U.S. authorization includes bivalent shots manufactured by Pfizer and Moderna. Kids who received the initial two Moderna shots can get a single bivalent booster under Thursday’s new guidelines.

Children who haven’t gotten a third dose of the Pfizer vaccine will now be given the bivalent booster, but those who already received three shots aren’t yet eligible for the omicron-focused shot, the FDA said.

“Vaccines remain the best defense against the most devastating consequences of disease caused by the currently circulating omicron variant, such as hospitalization and death,” Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, said Thursday.