Favipiravir in High-risk COVID-19 Patients

Inclusion Criteria: * Patients are eligible to be included in the study only if they fulfil ALL the following criteria: * RT-PCR confirmed COVID-19 cases * Aged 50 years and above, AND have one or more co-morbidities * Within the first 7 days of illness (from symptom onset) * Mild to moderate clinical severity Exclusion Criteria: * Asymptomatic stage 1 patients * Patients with SpO2 less than 95% without oxygen therapy * Patients who needs oxygen supplements * Patients with concomitant bacterial or fungal infection (confirmed by culture) prior to initiation of study * Patients with congestive heart failure * Patients with severe hepatic impairment (\>Grade 3: ALT \>10 times of upper normal limit) * Impaired kidney function (creatinine clearance according to Cockcroft-Gault formula less than 30 ml/min) at the time of screening. * Malabsorption syndrome or other clinically significant gastrointestinal disease that may affect absorption of the study drug (non-correctable vomiting, diarrhea, ulcerative colitis, and others). * Pregnant or nursing women or women planning pregnancy. * Female patients who cannot consent to contraceptive use of oral contraceptives, mechanical contraceptives such as intrauterine devices or barrier devices (pessaries, condoms), or a combination of these devices from the start of favipiravir administration to 7 days after the end of favipiravir administration * Male patients whose partner cannot agree to use the contraception method described in (9) * Patients with a history of gout or on treatment for gout or hyperuricemia * Patients receiving immunosuppressants * Patients who received interferon or drugs with reported antiviral activity against COVID-19 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination) within 7 days of illness. * Patients in whom this episode of infection is a recurrence or reinfection of COVID-19 infection * Patients who have previously received favipiravir * Patients who are not able to provide written consent by themselves * Other patients judged ineligible by the principal investigator or sub-investigator