Antiviral Pill Cuts Household COVID-19 Infections in Trial

An antiviral pill has been shown to prevent COVID-19 in people exposed to the SARS-CoV-2 virus at home, according to trial results published in the New England Journal of Medicine. The study followed more than 2,000 household contacts from June 2023 to September 2024.

Participants received either ensitrelvir or a placebo within 72 hours of a housemate developing symptoms. About 3 percent of those who took the drug developed symptomatic illness, compared with 9 percent in the placebo group.

0 percent of the ensitrelvir group versus 21. The drug was generally well tolerated and did not produce the taste-related side effects sometimes linked to Paxlovid. The medication blocks an enzyme coronaviruses need to replicate. It targets the same enzyme as one of the active ingredients in Paxlovid, though that drug did not achieve statistically significant prevention in earlier household trials.

Japan’s health ministry approved ensitrelvir, sold as Xocova, for post-exposure prevention in March based on these results. U.S. decision expected within the next month. Study co-author Frederick Hayden said the drug could benefit older adults with comorbidities who face known exposure.

Clinicians continue to discuss which groups should receive the medication now that most people have immunity from vaccination or prior infection.