(Bloomberg) -- The U.S. has cleared Pfizer Inc.’s Covid pill, and now comes another hurdle -- deciding who should get it.

Pfizer’s Paxlovid, authorized Wednesday by the Food and Drug Administration, has shown promising results in substantially reducing severity in cases, with President Joe Biden hailing it as “a promising new treatment.” But it will be available in limited quantities at first as Pfizer grinds through a months-long manufacturing process. 

The U.S. is expected to receive 265,000 courses of treatment by the end of January, up to 2 million a month by spring and a total of 10 million by July. The National Institutes of Health’s guidelines committee is putting together a list of recommendations, and the U.S. government will get the pill through existing distribution channels that have been used for existing treatments -- sending them on a per-capita basis to states while also sending them to other entities, like federally qualified community health centers, in a bid to minimize any race gap in availability.

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But it will ultimately be up to doctors to prescribe who gets Paxlovid at first and who gets an alternative.

“It almost certainly will be a physician writing a prescription for someone who within the first three days of notable symptoms of Covid, and is in a high-risk group to get it,” Anthony Fauci, Biden’s chief medical adviser, said Wednesday. “It’s, obviously, a very difficult situation when you have a limited supply.” 

The NIH recommendation will also weigh whether another treatment may be more appropriate, such as remdesivir or a monoclonal antibody, Fauci said. The recommendation will target the most high-risk, which “is what you want this to be for, since we have a limited supply, that we would have a prioritization of what the best approach would be,” Fauci said.

Doctors could also turn to Merck & Co.’s pill, molnupiravir, developed with partner Ridgeback Biotherapeutics LP. It’s not yet authorized but is expected to be this week. 

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