The FDA authorized Pfizer/BioNTech's (PFE/BNTX) bivalent COVID-19 booster for children ages 5-11 and Moderna's (MRNA) bivalent booster for ages 6-17, expanding access to protection against circulating variants for all but the youngest population.

"As the various waves of COVID-19 have occurred, more children have gotten sick with the disease and have been hospitalized. Children may also experience long-term effects, even following initially mild disease," the FDA's Dr. Peter Marks said in a statement, noting that the disease for kids has been less severe than for adults.

The BA.4/BA.5 variant-targeting shots still await approval from the Centers for Disease Control and Prevention.

“As families across the country take part in fall festivities and plan for the upcoming holiday season, we aim to provide school-aged children with additional protection against the Omicron BA.4/BA.5 sub-variants, which continue to account for more than 80% of cases in the U.S.,” said Pfizer CEO Albert Bourla in a statement.

Similar to the adult boosters, the kids' boosters have been authorized by the FDA based on pre-clinical data, as existing trials to test the efficacy of the vaccine are underway. The move caused some controversy among vaccine experts, but many still support its use.

Phase 2/3 trials were conducted for the original Omicron strain, BA.1, and showed strong protection against that and other circulating strains.

BioNTech CEO Ugur Sahin said in a statement the companies are also starting clinical trials for the youngest age groups.

“In addition, we have started a clinical trial to evaluate the adapted vaccine based on the BA.4 and BA.5 subvariants in children six months through 11 years of age aiming to offer all age groups the opportunity to immunize against Omicron variants and subvariants," he said.

The new boosters can be administered at least 2 months after a primary series or a monovalent booster, the latter of which was authorized earlier this year.