Update (December 23): The US Food and Drug Administration today issued an emergency use authorization for Merck’s oral antiviral drug molnupiravir for non-severe COVID-19 disease cases in high-risk adults when no alternative treatments are available.

The US Food and Drug Administration announced yesterday (December 22) an emergency use authorization of Pfizer’s Paxlovid, an antiviral pill regimen, for treatment of mild-to-moderate COVID-19. The drug is the first orally administered option available for the disease, and comes as the Omicron variant, now dominant in the US, is proving resistant to some of the antibody therapies currently in use for COVID-19.

“This authorization provides a new tool to combat COVID-19 at a crucial time in the pandemic as new variants emerge and promises to make antiviral treatment more accessible to patients who are at high risk for progression to severe COVID-19,” Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research, said in a statement.

Paxlovid consists of two pills taken together over the course of five days. Nirmatrelvir interferes with viral replication, and ritonavir slows the breakdown of nirmatrelvir. In a Phase 2/3 clinical trial, the regimen reduced the risk of hospitalization and death by 89 percent in patients at risk for severe disease, Pfizer announced last month. The results have not yet been published in a peer reviewed journal.

In preparation for the FDA’s authorization of Paxlovid, Pfizer stocked a warehouse in Memphis, Tennessee, with tens of thousands of pill packs and has been aiming to produce 30 million treatments by the middle of next year, The Washington Post reports. The US already secured an advance purchase of 10 million packs for about $5.3 billion.

Even still, experts predict there will continue to be treatment shortages as cases rise in the face of the Omicron surge. “There’s no question that it appears we’re in a canoe that is about to go over a significant waterfall,” Bruce Farber, chief of the infectious diseases division at the New York healthcare system Northwell Health, tells the Post. Farber adds that Northwell may soon run out of monoclonal antibody treatments.

Ralph Madeb, co-chief medical officer at New York Community Hospital, agrees. “Demand right now is just infinite,” he tells the Post. “It’s something I’ve never seen before.”

A second antiviral pill for COVID-19, from Merck, has been authorized in the UK and is currently pending an FDA greenlight.