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Ensitrelvir Slashes Post-Exposure COVID Infections 66%, FDA Decision Near

5/18/2026

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Summary

Story summary

Ensitrelvir reduced post-exposure COVID-19 infections by two-thirds in a trial of 2,041 household contacts.
Participants received 375 mg on day one followed by 125 mg daily for four days within 72 hours of exposure.
Side effects occurred in 15 % of both the ensitrelvir and placebo groups.
Regulators expect a U.S. FDA decision as early as next month, which would make ensitrelvir the only post-exposure prophylactic if approved.

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Story summary

Ensitrelvir reduced post-exposure COVID-19 infections by two-thirds in a trial of 2,041 household contacts.
Participants received 375 mg on day one followed by 125 mg daily for four days within 72 hours of exposure.
Side effects occurred in 15 % of both the ensitrelvir and placebo groups.
Regulators expect a U.S. FDA decision as early as next month, which would make ensitrelvir the only post-exposure prophylactic if approved.