The Prevent Severe COVID-19 (PRESECO) Study

Inclusion Criteria: * Adults age 18 or older * Tested positive for SARS-CoV-2 by RT-PCR assay using a respiratory tract sample (either nasopharyngeal swab OR oropharyngeal swab OR nasal aspirate OR tracheobronchial aspirate OR saliva) collected within 72 hours of randomization * Stated willingness to give their written informed consent to participate in the study * Stated willingness to comply with all study procedures and availability for the duration of the study * Males must be sterile, OR agree not to donate semen AND agree to strictly adhere to contraceptive measures during the study and for 7 days following the last dose of study medication * Females must be unable to bear children, OR ensure that their male partner is incapable of fathering a child, OR, if of childbearing potential will strictly adhere to contraceptive measures during the study and for seven days following the last dose of study medication * Females must agree to stop breast-feeding prior to first dose of study drug and through seven days after completing therapy * Females must have a negative pregnancy test at screening * Ability to take oral medication and be willing to adhere to the favipiravir/placebo regimen * Subject has access to a smart phone, tablet, or PC * Minimal baseline severity score for COVID-19-related symptoms: at least two symptoms with a score of 2 or higher. COVID-19-related symptoms (excluding changes in the sense of taste or smell) include: * stuffy or runny nose * sore throat * shortness of breath * cough * lack of energy or tiredness * muscle or body aches * headache * chills or shivering * feeling hot or feverish * nausea * diarrhea * vomiting Exclusion Criteria: * O2 saturation \<94% * Shortness of breath at rest * Heart rate ≥ 125 per minute * COVID-19 symptoms first presented \>5 days prior to randomization * Requirement for hospitalization at the time of enrollment * Participation in another trial or use of any experimental treatment for COVID-19 * Treatment with high steroid dose i.e. \>30 mg/day prednisolone equivalent (excluding stable chronic treatment) or remdesivir or anyone receiving SARS-CoV-2 monoclonal antibodies within 3 months prior to enrollment * Known sepsis or organ dysfunction/ failure * Known infection with a respiratory virus other than SARS-CoV2 (e.g. Influenza) or any known bacterial infection (affecting the respiratory system or any other system) * Inability to adhere to study requirements * For premenopausal women: unwilling or unable to use effective birth control measures * Known allergy to favipiravir * Known end-stage kidney disease or requiring hemodialysis or continuous ambulatory peritoneal dialysis (CAPD) * Known liver impairment greater than Child-Pugh A * Psychiatric illness that is not well controlled (defined as stable on a regimen for more than one year). * Known elevated uric acid levels in the past year or taking uric acid lowering medications (allopurinol, febuxostat) * History of hereditary xanthinuria or history of xanthine urolithiasis. * History of gout or actively being treated for gout. * Current use of the following medications, which cannot be discontinued for the duration of the study: pyrazinamide, hydralazine, more than 3000 mg of acetaminophen per day.