Ensitrelvir Prevents COVID-19 After Exposure to Infected Individuals

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By Elana Gotkine HealthDay Reporter

Medically reviewed by Carmen Pope, Senior Medical Editor, B. Pharm. Last updated on May 15, 2026.

via HealthDay

FRIDAY, May 15, 2026 -- For persons who are severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-negative but are household contacts of a patient with COVID-19, ensitrelvir administered within 72 hours of symptom onset in the index patient is effective for preventing COVID-19, according to a study published in the May 14/21 issue of the New England Journal of Medicine.

Frederick G. Hayden, M.D., from the University of Virginia School of Medicine in Charlottesville, and colleagues conducted a double-blind, randomized trial involving persons who were SARS-CoV-2-negative on local diagnostic testing but were household contacts of a patient with COVID-19. Participants were randomly assigned to receive either ensitrelvir (375 mg on day 1 and 125 mg daily on days 2 through 5) or placebo within 72 hours after symptom onset in the index patient.

The modified intention-to-treat population included 1,030 and 1,011 patients in the ensitrelvir and placebo groups, respectively. The researchers found that the incidence of COVID-19 was lower in the ensitrelvir group versus the placebo group (2.9 versus 9.0 percent; risk ratio, 0.33). The two groups had a similar incidence of adverse events during the trial (15.1 and 15.5 percent in the ensitrelvir and placebo groups, respectively) and a similar incidence of serious adverse events (0.2 percent in each group). There were no reports of COVID-19-related hospitalizations or deaths.

"These first, clearly positive results with an oral antiviral underscore ensitrelvir's potential to protect a range of individuals from COVID-19, including those at higher risk of severe disease and potentially in other settings," Hayden said in a statement.

The study was funded by Shionogi, the manufacturer of ensitrelvir.

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Source: HealthDay

Posted : 2026-05-16 02:24

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