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Pill Works Against Omicron in Lab

The main ingredient in Pfizer's antiviral pill to treat SARS-CoV-2 worked against the Omicron variant in lab tests, according to the Wall Street Journal.

The pill, called Paxlovid, received emergency use authorization from the US Food and Drug Administration in December after studies found that it led to an 89 percent reduction in risk of COVID-19-related hospitalizations or deaths when taken as three pills twice a day for five days.

But as the Journal notes, there were concerns that Paxlovid, as well as Merck and Ridgeback Biotherapeutics' oral antiviral treatment, might be less effective against the Omicron variant of SARS-CoV-2. Pfizer announced this week, though, that three studies have indicated that nirmatrelvir, the main protease inhibitor in Paxlovid, could still block the protease it targets, that nirmatrelvir still had antiviral activity against Omicron, and that a similar concentration of nirmatrelvir was needed to be effective against Omicron and other variants.

The Journal notes that antiviral pills to treat SARS-CoV-2 are expected to be helpful against COVID-19 as they can be taken at home, but the complicated chemistry involved in manufacturing Paxlovid means that its supply is currently limited as manufacturing ramps up.