(Bloomberg) -- President Joe Biden said that most Americans with the Pfizer Inc.-BioNTech SE Covid-19 vaccine will be able to get a booster shot, after one of his top health officials overruled an advisory panel to expand eligibility.

“The majority of Americans who were fully vaccinated with the Pfizer vaccine are now able to receive the booster shot six months after they’ve received their second shot,” Biden said Friday at the White House.

The Centers for Disease Control and Prevention director, Rochelle Walensky, issued a statement late Thursday advising that booster shots could be given to people with the Pfizer vaccine 6 months after the second of their first two shots. 

Her statement broadened eligibility for the shots beyond the recommendations of a CDC advisory panel and the Food and Drug Administration, which authorized Pfizer boosters last week. But Biden said Walensky was in-line with medical science.

“The decision of which booster shot to give, when to start the shot, and who will get them, is left to the scientists and the doctors,” Biden said. “That’s what happened here.”

In particular, Walensky said that people age 18 to 64, who have no underlying medical conditions but who work in places with a high chance of Covid-19 exposure, would be able to get a shot.

She also opened eligibility to those 65 and up and those age 50 to 64 with underlying medical conditions, saying both groups should get a booster.

And she said people age 18 to 49 with underlying medical conditions could get a booster “based on their individual benefits and risks” without saying whether they should get a third shot. 

(Updates with additional Biden remark in second paragraphs)

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