* 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.

* 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.

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.

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.

- o2 saturation <94% - shortness of breath at rest - heart rate ≥ 125 per minute - requirement for hospitalization at the time of enrolment - participation in another trial or use of any experimental treatment for covid-19 - treatment with high steroid dose (excluding stable chronic treatment) or remdesivir - evidence of 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) - 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.

- o2 saturation <94% - shortness of breath at rest - heart rate ≥ 125 per minute - requirement for hospitalization at the time of enrolment - participation in another trial or use of any experimental treatment for covid-19 - treatment with high steroid dose (excluding stable chronic treatment) or remdesivir - evidence of 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) - 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.

- o2 saturation <94% - shortness of breath at rest - heart rate ≥ 125 per minute - requirement for hospitalization at the time of enrolment - participation in another trial or use of any experimental treatment for covid-19 - treatment with high steroid dose (excluding stable chronic treatment) or remdesivir - evidence of sepsis or organ dysfunction/ failure - current hospitalization or requiring hospital admission at screening or enrollment - inability to adhere to study requirements - for premenopausal women: unwilling or unable to use effective birth control measures - known allergy to favipiravir - renal insufficiency requiring hemodialysis or continuous ambulatory peritoneal dialysis (capd) or glomerular filtration rate of less than 20 ml/min. - 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). - history of elevated uric acid - psychiatric disease that is not well controlled where controlled is defined as: stable on a regimen for more than one year. - 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.

- o2 saturation <94% - shortness of breath at rest - heart rate ≥ 125 per minute - requirement for hospitalization at the time of enrolment - participation in another trial or use of any experimental treatment for covid-19 - treatment with high steroid dose (excluding stable chronic treatment) or remdesivir - evidence of sepsis or organ dysfunction/ failure - current hospitalization or requiring hospital admission at screening or enrollment - inability to adhere to study requirements - for premenopausal women: unwilling or unable to use effective birth control measures - known allergy to favipiravir - renal insufficiency requiring hemodialysis or continuous ambulatory peritoneal dialysis (capd) or glomerular filtration rate of less than 20 ml/min. - 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). - history of elevated uric acid - psychiatric disease that is not well controlled where controlled is defined as: stable on a regimen for more than one year. - 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.