FDA Approves Ensitrelvir to Prevent COVID-19 After Exposure

Phase 3 data showed a 67% reduction in symptomatic infection among exposed household contacts who tested negative at baseline.

By
Kathryn Wighton
June 2, 2026
3 min

MDSpire News

Overview

Revise to remove unsupported claims and ensure all statements are directly sourced.

Background

Remove subjective language regarding the importance of postexposure prophylaxis.

Data Highlights

Outcome	Ensitrelvir	Placebo
Symptomatic COVID-19 by Day 10	2.9%	9.0%
Relative Risk Reduction	67%	N/A
Adverse Events	15.1%	15.5%

Key Findings

Ensitrelvir reduced the risk of symptomatic COVID-19 by 67% compared to placebo.
The primary analysis included 2,041 participants with negative SARS-CoV-2 tests at baseline.
Participants began treatment within 72 hours of symptom onset in the household member.
Common adverse events included headache, diarrhea, and cough, with similar rates in both treatment groups.
Ensitrelvir is administered as a 5-day regimen.

Clinical Implications

Ensitrelvir provides a new oral option for postexposure prophylaxis against COVID-19, which may be particularly beneficial in household and high-risk settings. Clinicians should consider this treatment for eligible patients following exposure to COVID-19.

Conclusion

The approval of ensitrelvir marks a significant advancement in the prevention of COVID-19 following exposure, offering a new tool for healthcare providers in managing potential outbreaks.