• The CDC approval comes a day after the Food and Drug Administration gave its authorization.
• Children ages 6 months through 5 years old who received the two-dose Moderna can now get an omicron booster.
• Kids ages 6 months through 4 years old who are completing their Pfizer primary series will receive the omicron shot as their third dose.

The Centers for Disease Control and Prevention on Friday signed off on omicron vaccines for children as young as 6 months old, giving pharmacies and physicians the green light to start administering the shots.

Children ages 6 months through 5 years old who received the two-dose Moderna primary series can now get an omicron booster two months after their second dose.

Meanwhile, kids ages 6 months through 4 years old who are completing their Pfizer primary series will received the omicron shot as their third dose.

The CDC approval comes a day after the Food and Drug Administration gave its authorization. The CDC's independent panel of vaccine experts did not meet to discuss the available data before the agency gave the greenlight.

Dr. Peter Marks, head of the FDA's vaccine division, told parents in a statement Thursday that the agency carefully reviewed the data before authorizing the vaccines for the youngest children.

"Vaccines remain the best defense against the most devastating consequences of disease caused by the currently circulating omicron variant, such as hospitalization and death," Marks said. "Parents and caregivers can be assured that the FDA has taken a great deal of care in our review."

Covid infections and hospitalizations are increasing in the U.S. after the Thanksgiving holiday as subvariants that evade immunity more easily have become dominant. During the omicron wave last winter, hospitalizations of children ages 4 and under were five times higher than at the peak of the previous delta wave.

The vast majority of children ages 5 and under have not received a single dose of a Covid vaccine, according to the CDC. Some 95% of children are either unvaccinated or have not completed their primary series of shots, according to the agency.

In a statement Friday, the CDC said it was working with parents to improve confidence in the vaccines. It encouraged parents to talk to their children's physicians about staying up to date on their shots.

The omicron shots target both the BA.5 subvariant and the original strain of Covid. Data from Pfizer and Moderna indicate that they trigger a better immune response in adults than the old shots do, though smaller independent studies found they weren't much better.

Scientists generally expect the shots will prevent hospitalizations, but likely won't do as well in curbing mild illness.