A Study of Secutrelvir in Participants With Coronavirus Disease 2019 (COVID-19) Who Are at High Risk for Progression to Severe Disease

The primary purpose of this study is to evaluate the efficacy and safety of secutrelvir in symptomatic nonhospitalized adult and adolescent participants with COVID-19 who are at high risk for progression to severe disease.

Key Inclusion Criteria: * Must be 12 to \24 hours hospitalization for any medical procedure through Day 28. * Documented respiratory infection (for example, influenza, respiratory syncytial virus) other than COVID-19 within the 14 days prior to the screening visit. * Known history of cirrhosis or liver decompensation (including ascites, variceal bleeding, or hepatic encephalopathy). * Known history of any of the following abnormalities in the following clinical laboratory tests (within 6 months prior to the screening visit): * Total bilirubin ≥2\*upper limit of normal (ULN) (except for Gilbert's syndrome) * Aspartate aminotransferase or alanine aminotransferase ≥3\*ULN * Suspected or confirmed COVID-19 unrelated to the current episode within 6 months prior to randomization or, for moderately immunocompromised participants, within 3 months prior to randomization. * Suspected or confirmed concurrent active systemic infection other than COVID-19 that may interfere with the evaluation of response to the investigational intervention. * Ongoing long COVID-19 or post-acute sequelae of COVID-19 diagnosis. * Current severely immunocompromised conditions. * Received any other COVID-19-specific therapies within the following timeframes: * Antiviral agents (for example, remdesivir, nirmatorelvir/ritonavir, molnupiravir, ensitrelvir) within 30 days or 5 half-lives (whichever is longer) prior to randomization * Anti-SARS-CoV-2 monoclonal antibodies and COVID-19 convalescent plasma within 6 months prior to randomization Note: Other protocol-define criteria apply