Moncef Slow We head of Operation Warp Speed, the federal vaccine program, said on CBS's Face the Nation that officials were in talks with Moderna and the Food and Drug Administration about the idea.

Madonna's vaccine requires two injections.

That would mean people aged 18 to 55 would receive half the current quantity in each of the 1st and 2nd doses.

Slowly, said quote.

We know it induces identical immune response, noting that ultimately it would be up to the FDA to make such a decision.

Moderna and the FDA could not immediately be reached for comment.

The U.

S Centers for Disease Control and Prevention said it had administered more than four million first doses of Cove in 19 vaccines in the country as of Saturday morning and distributed over 13 million doses.

The U.

S has also approved a vaccine from Pfizer, which like Madonna's, requires two shots.