Updated · University of Minnesota Twin Cities · May 14
Ensitrelvir Cuts Household COVID Risk 67% in Phase 3 Trial
Updated
Updated · University of Minnesota Twin Cities · May 14
Ensitrelvir Cuts Household COVID Risk 67% in Phase 3 Trial
5 articles · Updated · University of Minnesota Twin Cities · May 14
2.9% of household contacts given ensitrelvir developed symptomatic COVID-19 by day 10, versus 9.0% on placebo, in a phase 3 trial of more than 2,000 exposed participants.
72-hour dosing after the index patient’s symptom onset drove the benefit; 71.1% were enrolled within 48 hours, and infections rose quickly in the placebo group by day 2.
15.1% of ensitrelvir recipients reported adverse events versus 15.5% on placebo, with serious events at 0.2% in both groups and no COVID-related hospitalizations or deaths.
34% lower household transmission and consistent benefits in older and higher-risk contacts suggest the drug could extend beyond treatment into postexposure prevention, a use already approved in Japan.
While this new drug can prevent COVID, could its widespread use inadvertently create drug-resistant virus strains?
If a pill can stop COVID after exposure, will people become less cautious about getting infected in the first place?
With a key FDA decision next month, will this drug become America's first approved pill to prevent COVID-19 after exposure?
Ensitrelvir’s 67% Risk Reduction in COVID-19: Phase 3 SCORPIO-PEP Trial Signals New Era for Post-Exposure Prophylaxis
Overview
The global Phase 3 SCORPIO-PEP trial, led by Shionogi & Co., Ltd., revealed that ensitrelvir (Xocova) is effective in preventing COVID-19 after exposure, with results published in the New England Journal of Medicine in May 2026. The study highlighted ensitrelvir’s strong antiviral action and its potential as a convenient oral option for post-exposure prevention. However, the trial excluded pregnant women, so its safety in this group is unknown. Ensitrelvir can also interact with other drugs due to its effect on cytochrome P450 3A, which clinicians must consider. These findings mark a major step in COVID-19 prevention strategies.