WASHINGTON — The U.S. has authorized the first pill against COVID-19, a Pfizer drug that Americans can take at home to reduce the risk of hospitalization and death.

The Food and Drug Administration announcement comes as the U.S. braces for a wave of new infections from the omicron variant that is threatening already-strained hospitals.

Pfizer's prescription pill, which it calls Paxlovid, is the first U.S. medication that doesn't require an injection or an IV, a long-awaited milestone in the battle against the virus. But initial supplies will be extremely limited, with just enough to treat tens of thousands of people.

The drug was authorized for high-risk patients who are most likely to get severe illness.

Pfizer said earlier this month that trial results show the pill cut rates of hospitalization by nearly 90% among patients with mild-to-moderate infections.

A similar pill from competitor Merck is currently under FDA review and has been cleared by regulators for use in the U.K.

Pfizer said Tuesday morning that final trial studies still show its experimental COVID-19 pill significantly reduced the risk of hospitalization or death linked to the virus, by 89%.

The company also said Tuesday in its press release that a lab test indicated that the drug should be effective against omicron. The newly-discovered COVID-19 variant strain has medical experts concerned about a potential surge in cases.

"This news provides further corroboration that our oral antiviral candidate, if authorized or approved, could have a meaningful impact on the lives of many, as the data further support the efficacy of PAXLOVID in reducing hospitalization and death and show a substantial decrease in viral load. This underscores the treatment candidate's potential to save the lives of patients around the world," Pfizer CEO Albert Bourla said. "Emerging variants of concern, like omicron, have exacerbated the need for accessible treatment options for those who contract the virus, and we are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic."

The pill, which Pfizer calls Paxlovid, is taken twice a day for five days upon a COVID-19 diagnosis. Pfizer says just the final results show that just 0.7% of the patients who received the pill in the double-blind trial were hospitalized. By comparison, 6.5% of patients who received a placebo were hospitalized or died of the virus.

Pfizer added that "relative risk reduction was 94% in patients 65 years of age or older," and that just 1.1% of people in that age group that received the pill were either hospitalized or were killed by the virus.

The final results released on Tuesday were largely consistent with the initial late-stage trial results Pfizer released in November.

A similar pill from another drugmaker, Merck, is also currently under FDA review. Should they be approved, the pills made by Pfizer and Merck would be the first oral treatment for COVID-19 — all therapies currently authorized in the U.S. require an IV or injection.

Both Pfizer and Merck have already announced a partnership with the UN that will allow drugmakers worldwide to copy the formulas for their anti-COVID-19 pills in the hopes of increasing access to the drug in lower- and middle-income countries.