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

"An international study of more than 2,000 household contacts conducted from June 2023 to September 2024, about 9% of people who got a placebo within 72 hours of a housemate developing symptoms became symptomatic themselves, compared with only about 3% of those who got a five-day course of ensitrelvir. Rates of viral transmission were lower in the ensitrelvir group, too: confirmed infections, symptomatic or not, turned up in only 14.0% of those who received the drug, compared with 21.5% of those who got a placebo."

"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, ensitrelvir has come through."

"The therapy generally proved tolerable, without the taste-related side effects often seen with Paxlovid and, overall, similar toxicity as the placebo. Japan's health ministry approved ensitrelvir, marketed as Xocova, in March for post-exposure use on the strength of these trial data."

"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."

An antiviral pill called ensitrelvir was shown to prevent COVID-19 in people exposed to SARS-CoV-2 at home. In an international trial of more than 2,000 household contacts, about 9% of placebo recipients who took no antiviral within 72 hours of a housemate developing symptoms became symptomatic, compared with about 3% of those who received a five-day course of ensitrelvir. Viral transmission was also lower, with confirmed infections occurring in 14.0% of the ensitrelvir group versus 21.5% of the placebo group. The treatment was generally tolerable, with toxicity similar to placebo and fewer taste-related side effects than Paxlovid. Japan approved ensitrelvir for post-exposure use based on these results.

Read at Nature