At last, a pill that can prevent COVID after exposure to infected people

Xocova (ensitrelvir) has been approved for COVID-19 prevention in Japan on the basis of promising trial results. Credit: The Yomiuri Shimbun via AP Images/Alamy An antiviral pill has, for the first time, been shown to prevent COVID-19 in people exposed to the SARS-CoV-2 virus at home, according to trial results published today in the New England Journal of Medicine 1 . The drug could be a lifeline for those who still face real danger from the virus, such as care-home residents or transplant recipients on immune-suppressing medication. The advance arrives years after the peak of the COVID-19 pandemic, so the real-world impact might be felt by only a narrow band of individuals. Still, “as a 78-year-old with comorbidities, I certainly would use it if I had a known exposure”, says study co-author Frederick Hayden, a clinical virologist at the University of Virginia School of Medicine in Charlottesville. Antiviral antidote The drug, called ensitrelvir , is made by the Japanese pharmaceutical company Shionogi. It blocks an enzyme that coronaviruses need to make new copies of themselves, hitting the same target as one of the two active ingredients in Pfizer’s antiviral Paxlovid . But whereas that ingredient, nirmatrelvir, failed to prevent household infections in trials 2 , ensitrelvir has come through. …