A drug already approved to treat covid-19 in some countries is looking even more impressive. Research out this week shows that the medication, called ensitrelvir, can effectively prevent people from catching the viral disease, too. Scientists in the U.S., Japan, and U.K. conducted a phase III trial of the drug. People who took ensitrelvir (pronounced en-SIH-trel-veer) were substantially less likely to contract covid-19 from someone in their home compared to a placebo, the trial found. The drug’s makers have submitted it to the U.S. Food and Drug Administration for approval as a prophylactic for covid-19, with a decision expected in the next few months. “In this trial, the prompt initiation of oral ensitrelvir postexposure prophylaxis was effective in preventing Covid-19 in household contacts, including those with risk factors for severe disease, without apparent safety concerns,” the researchers wrote in their paper, published Wednesday in the New England Journal of Medicine. A newer generation of antiviral Ensitrelvir was developed by the Japan-based pharmaceutical Shionogi & Co. It’s designed to inhibit the main protease—an enzyme that breaks down proteins—found in coronaviruses, including SARS-CoV-2, the cause of covid-19. By doing so, it hinders the virus’ ability to make more of itself.