Fluvoxamine for Adults With Mild to Moderate COVID-19

The investigators will randomize approximately 400 participants, age 18 and older, who have laboratory-confirmed, mild to moderate COVID-19 and are admitted to community treatment centers. All interactions for this study will be conducted remotely by videoconferencing, mobile application, or phone. Screening Phase: All patients admitted to community treatment centers receive self-monitoring equipment, including an oxygen saturation monitor, blood pressure monitor, and thermometer. All participants will first complete a pre-screen to see if they may be eligible for the study. Once a participant is confirmed eligible and consented, the study team will deliver study drugs to each participant room. RCT Phase: Participants will be randomly assigned (1:1) to take either fluvoxamine or placebo (ursodeoxycholate). This phase of the study will last until discharge from community treatment centers (usually 10 days) and is single-blinded as the participants will not know which treatment they receive. Participants will take up to 100 mg of fluvoxamine or placebo by mouth twice a day for a daily total of 200 mg. Participants will continue this dose until discharge from community treatment centers (for approximately 10 days). The dose may be adjusted depending on tolerability. Participants will complete short 10 minute assessments twice a day to report the results of self-monitoring (oxygen saturation, blood pressure, and temperature), COVID-19 symptoms, and any adverse events using mobile application or phone. Follow-up Phase: The study team will follow participants for approximately 30 days after the end of the randomized phase (after discharge from community treatment centers) using phone.