The primary objective of this study is to investigate the antiviral effect of S-892216 in participants with coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Key Inclusion Criteria:

• Must weigh ≥40 kilograms
• Must have at least 2 COVID-19 signs/symptoms of mild or higher severity, or at least 1 sign/symptom of moderate or higher severity, within the 72 hours prior to randomization, and the symptoms must still be present in the 24 hours prior to randomization
• Documentation of laboratory-confirmed active SARS-CoV-2 infection, as determined by a nucleic acid (for example, qRT-PCR) or antigen test from any respiratory tract specimen (for example, oropharyngeal, NP or nasal swab, or saliva), or any other SARS-CoV-2 test approved according to local regulations, collected ≤72 hours (3 days) prior to randomization
• Oxygen saturation (SpO2) of ≥92% on room air adjusted for altitude and obtained at rest by study staff within the 24 hours prior to randomization. For a potential participant who regularly receives chronic supplementary oxygen for an underlying lung condition, SpO2 measured while on standard home oxygen supplementation level must be ≥92%.
• Capable and willing to complete an electronic participant diary
• Contraceptive use by female participants should be consistent with local regulations regarding the use of contraceptive methods for those participating in clinical studies. Note: The investigational medication may lead to an increase or decrease of sex hormone levels; therefore, hormonal contraception must not be used alone and must be combined with a barrier method.
• A woman of childbearing potential must have a negative urine pregnancy test within the 24 hours before the first dose of investigational intervention
• Must be randomized ≤72 hours from onset of COVID-19 symptoms (defined as the time point when at least 1 of the COVID-19 symptoms occurs)
• Agrees to not participate in another clinical trial for the treatment of COVID-19 or SARS-CoV-2 during the study period unless meeting hospitalization criteria or reaching Day 28, whichever is earliest

Key Exclusion Criteria:

• High risk of progression to severe COVID-19, as defined in the protocol

• Documented respiratory infection (for example, influenza, respiratory syncytial virus) other than COVID-19 within the 14 days prior to the screening visit

• Known current renal impairment defined as estimated glomerular filtration rate <60 milliliters/minute/1.73 meters squared or requiring dialysis

• 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 the 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 ≥2 × ULN

• A QT interval corrected using Fridericia's formula at the screening visit:

  • For males: >450 milliseconds (msec)
  • For females: >470 msec

• History of hospitalization for the current SARS-CoV-2 infection or anticipated need for hospitalization within 24 hours after randomization

• History of cancer except for basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for 3 years

• Women with a history of osteoporosis

• Received or expected to receive any dose of a SARS-CoV-2 vaccine within 14 days of randomization or during the study through day 28

• Received or expected to receive any other COVID-19-specific treatment, including outpatient remdesivir, Paxlovid, molnupiravir, monoclonal antibodies, ensitrelvir, and convalescent plasma for the current COVID-19 infection

• Exposed to an investigational drug within 30 days or 5 half-lives of the drug prior to the screening visit

Note: Other protocol-defined inclusion/exclusion criteria may apply.