Ensitrelvir Effective As Post-Exposure Prophylaxis Against COVID-19 Among Exposed Household Contacts, Study Finds

Infectious Disease Advisor (3/12, Nye) reports a study found that “postexposure prophylaxis with ensitrelvir was well tolerated and effective against COVID-19 among household contacts exposed to an index patient with laboratory-confirmed infection.” Researchers found that overall, “the rate of laboratory-confirmed COVID-19 infection was significantly lower among patients who received ensitrelvir vs placebo.” Additionally, “similar findings were observed in the intention-to-treat analysis, with ensitrelvir PEP significantly associated with reduced risk for infection.” Researchers concluded, “Administration of ensitrelvir to HHC [household contacts] <72 hours after the onset of IP [index patient] symptoms was effective and generally well tolerated for PEP in HHC, including those with HR [high-risk] factors.” The study was presented at the Conference on Retroviruses and Opportunistic Infections (CROI) 2025.