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The FDA on May 29, 2026 approved Xocova (ensitrelvir), Shionogi's five-day oral antiviral, for post-exposure prophylaxis of COVID-19 in adults and adolescents 12 and older following contact with an infected person.
Ensitrelvir inhibits the SARS-CoV-2 main protease, the enzyme nirmatrelvir also targets, and is taken without ritonavir alongside it. The course is 375 mg on day one and 125 mg on days two through five, started within 72 hours of contact.
SCORPIO-PEP randomized 2,387 household contacts across five countries. In the primary population of 2,041, symptomatic infection confirmed by PCR occurred in 2.9% on Xocova against 9.0% on placebo through day 10, a 67% reduction. Counting everyone randomized, including those already positive at baseline, the split was 4.4% against 10.2%. More than 99% of participants were seropositive at screening.
The label carries an embryofetal toxicity warning, requires a pregnancy check before dosing, and notes that ensitrelvir is a strong CYP3A inhibitor.
Shionogi has marketed ensitrelvir in Japan as a COVID-19 treatment since 2022. The US label covers prevention after exposure and nothing else, in the labeled population.
Sources: FDA prescribing information; Drugs@FDA, NDA 220442; Shionogi press release; SCORPIO-PEP (NCT05897541); AJMC
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