1. body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature 2. patients with spo2 less than 95% 3. patient requires supportive oxygen therapy 4. patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection 5. patients with proven concomitant systematic fungal infection prior to initiation of study drug. 6. patients with concurrent congestive heart failure (nyha iii-iv) 7. patients with severe hepatic impairment equivalent to grade c on child-pugh classification 8. patient with renal impairment requiring dialysis. 9. patients with disturbed consciousness such as disturbed orientation. 10. pregnant or possibly pregnant patients. 11. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation 12. male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. 13. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration 14. patients with herditary xanthinuria 15. patients who have hyperuricemia (\> 1 mg/dl) or xanthine urinary calculi 16. patients with a history of gout or on treatment for gout or hyperuricemia 17. patients receiving immunosuppressants 18. patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) 19. patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection 20. patients who have previously been treated with favipiravir (t-705a) 21. other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -

1. body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature 2. patients with spo2 less than 95% 3. patient requires supportive oxygen therapy 4. patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection 5. patients with proven concomitant systematic fungal infection prior to initiation of study drug. 6. patients with concurrent congestive heart failure (nyha iii-iv) 7. patients with severe hepatic impairment equivalent to grade c on child-pugh classification 8. patient with renal impairment requiring dialysis. 9. patients with disturbed consciousness such as disturbed orientation. 10. pregnant or possibly pregnant patients. 11. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation 12. male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. 13. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration 14. patients with herditary xanthinuria 15. patients who have hyperuricemia (\> 1 mg/dl) or xanthine urinary calculi 16. patients with a history of gout or on treatment for gout or hyperuricemia 17. patients receiving immunosuppressants 18. patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) 19. patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection 20. patients who have previously been treated with favipiravir (t-705a) 21. other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -

body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature patients with spo2 less than 95% patient requires supportive oxygen therapy patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection patients with proven concomitant systematic fungal infection prior to initiation of study drug. patients with concurrent congestive heart failure (nyha iii-iv) patients with severe hepatic impairment equivalent to grade c on child-pugh classification patient with renal impairment requiring dialysis. patients with disturbed consciousness such as disturbed orientation. pregnant or possibly pregnant patients. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration patients with herditary xanthinuria patients who have hyperuricemia (> 1 mg/dl) or xanthine urinary calculi patients with a history of gout or on treatment for gout or hyperuricemia patients receiving immunosuppressants patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection patients who have previously been treated with favipiravir (t-705a) other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -

body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature patients with spo2 less than 95% patient requires supportive oxygen therapy patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection patients with proven concomitant systematic fungal infection prior to initiation of study drug. patients with concurrent congestive heart failure (nyha iii-iv) patients with severe hepatic impairment equivalent to grade c on child-pugh classification patient with renal impairment requiring dialysis. patients with disturbed consciousness such as disturbed orientation. pregnant or possibly pregnant patients. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration patients with herditary xanthinuria patients who have hyperuricemia (> 1 mg/dl) or xanthine urinary calculi patients with a history of gout or on treatment for gout or hyperuricemia patients receiving immunosuppressants patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection patients who have previously been treated with favipiravir (t-705a) other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -

1. body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature 2. patients with spo2 less than 95% 3. patient requires supportive oxygen therapy 4. patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection 5. patients with proven concomitant systematic fungal infection prior to initiation of study drug. 6. patients with concurrent congestive heart failure (nyha iii-iv) 7. patients with severe hepatic impairment equivalent to grade c on child-pugh classification 8. patient with renal impairment requiring dialysis. 9. patients with disturbed consciousness such as disturbed orientation. 10. pregnant or possibly pregnant patients. 11. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation 12. male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. 13. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration 14. patients with herditary xanthinuria 15. patients who have hyperuricemia (> 1 mg/dl) or xanthine urinary calculi 16. patients with a history of gout or on treatment for gout or hyperuricemia 17. patients receiving immunosuppressants 18. patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) 19. patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection 20. patients who have previously been treated with favipiravir (t-705a) 21. other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -

1. body temperature of 37.5 °c or higher for more than 10 days after the onset of elevated body temperature 2. patients with spo2 less than 95% 3. patient requires supportive oxygen therapy 4. patients who show increased procalcitonin levels before the start of the study drug administration and are suspected to have concurrent bacterial infection 5. patients with proven concomitant systematic fungal infection prior to initiation of study drug. 6. patients with concurrent congestive heart failure (nyha iii-iv) 7. patients with severe hepatic impairment equivalent to grade c on child-pugh classification 8. patient with renal impairment requiring dialysis. 9. patients with disturbed consciousness such as disturbed orientation. 10. pregnant or possibly pregnant patients. 11. female patients who are woman of childbearing potential and unable to consent to the use of dual contraception from the start of favipiravir administration to 30 days after the end of favipiravir administration. dual contraception is a combination of two of the following: barrier method of contraception: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide; iud; hormone-based contraceptive; tubal ligation 12. male patients whose are unable to consent to the use of the barrier method of contraception (condom) from the start of favipiravir administration to 90 days after the end of favipiravir administration. male patients who are planning to donate sperm from the start up until 90 days after the end of favipiravir administration. 13. female patients who intend to breastfeed from the start of favipiravir administration until 14 days after discontinuation of favipiravir administration 14. patients with herditary xanthinuria 15. patients who have hyperuricemia (> 1 mg/dl) or xanthine urinary calculi 16. patients with a history of gout or on treatment for gout or hyperuricemia 17. patients receiving immunosuppressants 18. patients who received interferon-alpha or drugs with reported antiviral activity against sars-cov-2 (hydroxychloroquine sulfate, chloroquine phosphate, lopinavir-ritonavir combination, ciclesonide, nafamostat mesylate, camostat mesylate, remdesivir, etc.) within 9 days after fever onset (37.5°c or more) 19. patients in whom this episode of infection is a recurrence or a reinfection with the sars-cov-2 infection 20. patients who have previously been treated with favipiravir (t-705a) 21. other patients judged ineligible by the investigator, sub-investigator, or assigned physician. -