CROI 2025: Ensitrelvir significantly reduces risk of developing COVID-19 after household exposure

18 March 2025. Related: Early access, Conference reports, COVID-19, .

Simon Collins, HIV i-Base

An oral presentation of the phase 3 SCORPIO-PEP study supported using the protease inhibitor ensitrelvir as PEP to prevent COVID-19 in household settings. It is already approved in Japan for treatment of mild to moderate COVID-19.

Index cases needed to have tested positive and be symptomatic. Nearly 24,000 household contacts were randomised to a 50-day course of ensitrelvir or placebo within three days of symptom onset in the index case.

Approximate baseline demographics includes median age 42 (with 10% over 65), just over half were women and median BMI was 26. Approximately two-thirds enrolled in the US and one quarter in Japan, with about 70% enrolling within 48 hours of symptom onset in the index case and >99% were seropositive.

Ensitrelvir was associated with a highly significantly reduced risk of COVID-19 by day 10: 2.9% vs 9.0% with a risk ratio of 0.33 (95%CI: 0.22 to 0.49), p <0.0001.

Tolerability in the study was good with no new safety concerns.

Reference

Fukushi A et al for the SCORPIO-PEP Study Team. Ensitrelvir to Prevent COVID-19 in Households: SCORPIO-PEP. CROI 2025. Oral abstract 200.
www.croiconference.org/abstract/3747-2025/ (abstract)
watch.croiwebcasts.org/2025croi/ap/54366 (webcast for delegates)

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