Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, issued a statement allowing shots to begin immediately.
“Boosters are safe, and people over the age of 50 can now get an additional booster 4 months after their prior dose to increase their protection further,” Walensky said.
Also on Tuesday, the FDA cleared a fifth shot, or second booster, for that group. Previously, immunocompromised individuals were authorized to receive a three-dose primary series of a vaccine followed by a booster.
About a third of people ages 50 to 65 have significant underlying conditions that put them at risk of severe Covid, Dr. Peter Marks, the FDA’s top vaccine regulator, said during a briefing Tuesday. He added that it's possible people may need to get yet another dose of a Covid vaccine this fall.
That later dose may not be the same version of the shots currently in use and may transition to a variant-specific vaccine or one that targets more than one strain.
Both Pfizer and Moderna are testing a vaccine that targets the omicron variant. Moderna is also testing a shot that targets both the delta and omicron variants.