Oral Nirmatrelvir–Ritonavir as Postexposure Prophylaxis for Covid-19

This phase 2–3 double-blind, placebo-controlled trial evaluated the efficacy and safety of oral nirmatrelvir–ritonavir as postexposure prophylaxis for Covid-19 among 2736 asymptomatic adults exposed to a household contact with confirmed SARS-CoV-2 infection. Participants were randomized to receive nirmatrelvir–ritonavir for 5 or 10 days, or placebo. Symptomatic, confirmed infection occurred in 2.6% (5-day group), 2.4% (10-day group), and 3.9% (placebo), yielding non-significant relative risk reductions of 29.8% and 35.5%, respectively. Adverse events were similar across groups, with dysgeusia being most common. No serious safety concerns were identified. The trial, conducted during omicron predominance, did not meet its primary efficacy endpoint but supports further evaluation of antiviral prophylaxis strategies.

This phase 2–3 double-blind, placebo-controlled trial evaluated the efficacy and safety of oral nirmatrelvir–ritonavir as postexposure prophylaxis for Covid-19 among 2736 asymptomatic adults exposed to a household contact with confirmed SARS-CoV-2 infection. Participants were randomized to receive nirmatrelvir–ritonavir for 5 or 10 days, or placebo. Symptomatic, confirmed infection occurred in 2.6% (5-day group), 2.4% (10-day group), and 3.9% (placebo), yielding non-significant relative risk reductions of 29.8% and 35.5%, respectively. Adverse events were similar across groups, with dysgeusia being most common. No serious safety concerns were identified. The trial, conducted during omicron predominance, did not meet its primary efficacy endpoint but supports further evaluation of antiviral prophylaxis strategies.