A Study to Compare S-217622 With Placebo in Non-Hospitalized Participants With COVID-19

The main aim of this study is to evaluate the efficacy of S-217622 versus placebo among outpatient adults with mild and moderate COVID-19 starting intervention within 3 days of symptom onset.

Inclusion Criteria: * Documentation of laboratory-confirmed active SARS-CoV-2 infection, as determined by a nucleic acid (for example, reverse-transcriptase PCR) or antigen test from any respiratory tract specimen (for example, oropharyngeal, NP or nasal swab, or saliva) collected ≤72 hours (3 days) prior to randomization. * Participants are expected to begin study intervention ≤3 days from self-reported date of onset of any of the COVID-19-related symptoms from the following list: * Cough * Shortness of breath or difficulty breathing * Feeling feverish * Chills * Fatigue * Body pain or muscle pain or aches * Diarrhea * Nausea * Vomiting * Headache * Sore throat * Nasal obstruction or congestion * Nasal discharge * Loss of taste * Loss of smell * One or more of the following signs/symptoms present within 24 hours prior to randomization: * Cough * Shortness of breath or difficulty breathing * Feeling feverish * Chills * Fatigue * Body pain or muscle pain or aches * Diarrhea * Nausea * Vomiting * Headache * Sore throat * Nasal obstruction or congestion * Nasal discharge * Participants at higher risk of progression to severe COVID-19 are defined as follows: * Age ≥65 years * Age ≥18 with 1 of the following: * Obesity (body mass index \[BMI\] ≥30 kilograms per square meter \[kg/m\^2\]). Note: BMI is rounded to the nearest whole number, for example 29.5 kg/m\^2 is rounded to 30 kg/m\^2. * Diabetes mellitus * Hypertension requiring daily prescribed therapy * Cardiovascular disease (requiring daily prescribed therapy or congenital heart disease) * Chronic lung disease (for example, chronic obstructive pulmonary disease, moderate to severe asthma, interstitial lung disease, cystic fibrosis, pulmonary hypertension) requiring daily prescribed therapy * Chronic kidney disease, defined as known current kidney impairment with a creatinine clearance (CrCl) or estimated glomerular filtration rate (eGFR) \