FDA authorizes Covid omicron vaccines for children as young as 6 months old

The Food and Drug Administration on Thursday authorized updated Covid shots that target the omicron variant for children as young as 6 months old.

The eligibility rules vary depending on whether children received Moderna's or Pfizer's original vaccines as their primary series.

Here are the eligibility criteria:

The FDA, in a statement, said it did not authorize omicron shots for those children who already received three doses of Pfizer's vaccine because the agency is still waiting on supporting data for the booster dose. That data is expected in January and the FDA will review it as quickly as possible, the agency said.

The Centers for Disease Control and Prevention needs to sign off on the shots before pharmacies and physicians can start administering them.

Dr. Peter Marks, head of the FDA's vaccine division, told parents in a statement that the agency carefully reviewed the shots before authorizing them. Dr. Robert Califf, head of the FDA, said it's important for people to stay up to date on their shots this winter because immunity against the virus wanes.

"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," Califf said in a statement.

The authorizations come as Covid infections and hospitalizations are increasing in the wake of the Thanksgiving holiday. U.S. health officials are strongly encouraging everyone who is eligible to get vaccinated against Covid and the flu as respiratory viruses surge this season, putting strain on hospital emergency departments.

The new shots target the omicron BA.5 subvariant and the original Covid strain. U.S. health officials expect the new shots to provide superior protection compared with the original vaccines, which only target the original Covid strain. But the available efficacy and immune response data for adults has been mixed.

Omicron BA.5 has been displaced by the BQ.1 and BQ.1.1 subvariants, which taken together now make up a majority of infections in the U.S. The new shots likely won't perform as well against the BQ subvariants compared with BA.5 because they are more immune evasive, though they are still expected to provide good protection against severe illness.

The FDA authorized the shots based on adult immune response data for similar vaccines developed by Pfizer and Moderna that target the original omicron BA.1 variant. The safety data is also based on BA.1 clinical trial data as well as previous trials that evaluated the original vaccine as a booster.