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.…