First Covid antiviral pill wins FDA authorization

Pfizer revealed today that the FDA has authorized the emergency use of Paxlovid for the treatment of mild-to-moderate Covid-19 in adults and pediatric patients 12 years of age and older. The pills will be prescribed for use in those patients with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progression to severe Covid, including hospitalization or death.

The treatment includes nirmatrelvir, a novel main protease (Mpro) inhibitor originating in Pfizer’s laboratories, which was specifically designed to block the activity of the SARS-CoV-2 Mpro, an enzyme that the coronavirus needs to replicate. A full course of the drug is 30 pills—taken as three pills twice daily for five days.

Pfizer executives said the company is ready to begin delivery of Paxlovid in the US "immediately." Published reports on the news note, however, that initial supply of the antiviral drug will be limited. In November, Pfizer announced an agreement with the US government to supply 10 million treatment courses of Paxlovid, with delivery fulfillment expected to be completed in 2022.

The FDA based its emergency-use decision on clinical data from the Phase II/III EPIC-HR trial, which enrolled non-hospitalized adults aged 18 and older with confirmed Covid-19 who are at increased risk of progressing to severe illness. The data demonstrated an 89% reduction in the risk of Covid-related hospitalization or death from any cause in adults treated with Paxlovid, compared to placebo, within three days of symptom onset.