Additional Study Information: The main purpose of this study is to evaluate the ability of an experimental oral drug called S-217622 to improve the health of people with coronavirus disease 2019 (COVID-19). We also want to see if this study drug is safe, and if this study drug can shorten the time you have COVID-19 symptoms, reduce the amount of virus in the body, and prevent hospitalization or death. You will be eligible for this study if you are considered at lower risk for severe COVID-19 and have none of the risk factors that would put you at higher risk of disease progression. Study drug will be either an active study drug or a placebo. A placebo looks like a real drug, but it does not have any active study drug in it. This study will evaluate S-217622, an experimental drug that targets the virus that causes COVID-19 and may reduce the virus ability to reproduce. This study drug is taken for 5 consecutive days by mouth. The study will enroll approximately 1490 participants. Approximately 745 participants will be assigned to take S-217622 and approximately 745 participants will be assigned to take placebo. Approximately 50 people will participate at Columbia University Irving Medical Center. Participants must be at least 18 years of age to participate in this study. Participation in this study will last up to 24 weeks. If you are part of the study, the following study procedures will take place: record your symptoms, provide blood samples, and have nasopharyngeal swabs. You will be paid a minimum of $400 for completing all required study procedures.