1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. pregnancy (note that only post-menopausal women will be enrolled). 3. total bilirubin \>3x upper limit of normal or as per clinical judgment. 4. serum aspartate transaminase (ast) or alanine aminotransferase (alt) \>4x the upper limits of normal or as per clinical judgment. 5. hemoglobin \<7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count \<0.3 x 109/l at screening or as per clinical judgment. 6. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 7. egfr \<25 ml/ min/ 1.73 m2 or as per clinical judgment. 8. plasma and/or serum glucose \>300 or as per clinical judgment. 9. human immunodeficiency virus infection. 10. known active hepatitis b or c infection. 11. invasive fungal infection. 12. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 13. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 14. known condition associated with major immunodeficiency as per clinical judgment. 15. known hypersensitivity or allergy to fisetin. 16. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: * immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) * immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 17. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study. 18. history of diverticulitis or diverticulosis with gi bleeding, as per clinical judgment.

1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. pregnancy (note that only post-menopausal women will be enrolled). 3. total bilirubin \>3x upper limit of normal or as per clinical judgment. 4. serum aspartate transaminase (ast) or alanine aminotransferase (alt) \>4x the upper limits of normal or as per clinical judgment. 5. hemoglobin \<7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count \<0.3 x 109/l at screening or as per clinical judgment. 6. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 7. egfr \<25 ml/ min/ 1.73 m2 or as per clinical judgment. 8. plasma and/or serum glucose \>300 or as per clinical judgment. 9. human immunodeficiency virus infection. 10. known active hepatitis b or c infection. 11. invasive fungal infection. 12. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 13. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 14. known condition associated with major immunodeficiency as per clinical judgment. 15. known hypersensitivity or allergy to fisetin. 16. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: * immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) * immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 17. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study. 18. history of diverticulitis or diverticulosis with gi bleeding, as per clinical judgment.

presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. pregnancy (note that only post-menopausal women will be enrolled). total bilirubin >3x upper limit of normal or as per clinical judgment. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. plasma and/or serum glucose >300 or as per clinical judgment. human immunodeficiency virus infection. known active hepatitis b or c infection. invasive fungal infection. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. known condition associated with major immunodeficiency as per clinical judgment. known hypersensitivity or allergy to fisetin. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study. history of diverticulitis or diverticulosis with gi bleeding, as per clinical judgment.

presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. pregnancy (note that only post-menopausal women will be enrolled). total bilirubin >3x upper limit of normal or as per clinical judgment. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. plasma and/or serum glucose >300 or as per clinical judgment. human immunodeficiency virus infection. known active hepatitis b or c infection. invasive fungal infection. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. known condition associated with major immunodeficiency as per clinical judgment. known hypersensitivity or allergy to fisetin. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study. history of diverticulitis or diverticulosis with gi bleeding, as per clinical judgment.

presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. pregnancy (note that only post-menopausal women will be enrolled). total bilirubin >3x upper limit of normal or as per clinical judgment. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. plasma and/or serum glucose >300 or as per clinical judgment. human immunodeficiency virus infection. known active hepatitis b or c infection. invasive fungal infection. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. known condition associated with major immunodeficiency as per clinical judgment. known hypersensitivity or allergy to fisetin. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.

presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. pregnancy (note that only post-menopausal women will be enrolled). total bilirubin >3x upper limit of normal or as per clinical judgment. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. plasma and/or serum glucose >300 or as per clinical judgment. human immunodeficiency virus infection. known active hepatitis b or c infection. invasive fungal infection. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. known condition associated with major immunodeficiency as per clinical judgment. known hypersensitivity or allergy to fisetin. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.

1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. pregnancy (note that only post-menopausal women will be enrolled). 3. total bilirubin >3x upper limit of normal or as per clinical judgment. 4. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. 5. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. 6. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 7. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. 8. plasma and/or serum glucose >300 or as per clinical judgment. 9. human immunodeficiency virus infection. 10. known active hepatitis b or c infection. 11. invasive fungal infection. 12. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 13. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 14. known condition associated with major immunodeficiency as per clinical judgment. 15. known hypersensitivity or allergy to fisetin. 16. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: - immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) - immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 17. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.

1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. pregnancy (note that only post-menopausal women will be enrolled). 3. total bilirubin >3x upper limit of normal or as per clinical judgment. 4. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. 5. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥25,000/mm3 (≥25 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. 6. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 7. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. 8. plasma and/or serum glucose >300 or as per clinical judgment. 9. human immunodeficiency virus infection. 10. known active hepatitis b or c infection. 11. invasive fungal infection. 12. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 13. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 14. known condition associated with major immunodeficiency as per clinical judgment. 15. known hypersensitivity or allergy to fisetin. 16. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: - immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) - immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 17. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.

1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. mechanically-ventilated. 3. pregnancy (note that only post-menopausal women will be enrolled). 4. severe or critical covid19 (who/ nih severity categorization) at time of randomization. 5. total bilirubin >3x upper limit of normal or as per clinical judgment. 6. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. 7. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥20,000/mm3 (≥20 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. 8. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 9. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. 10. plasma and/or serum glucose >300 or as per clinical judgment. 11. cystatin c >3x upper limit of normal or as per clinical judgment. 12. human immunodeficiency virus infection. 13. known active hepatitis b or c infection. 14. invasive fungal infection. 15. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 16. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 17. known condition associated with major immunodeficiency as per clinical judgment. 18. known hypersensitivity or allergy to fisetin. 19. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: - immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) - immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 20. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.

1. presence of any condition that the investigator or the subject's attending physician, physician's assistant, or nurse-practitioner believes would put the subject at risk or would preclude the patient from successfully completing the trial. 2. mechanically-ventilated. 3. pregnancy (note that only post-menopausal women will be enrolled). 4. severe or critical covid19 (who/ nih severity categorization) at time of randomization. 5. total bilirubin >3x upper limit of normal or as per clinical judgment. 6. serum aspartate transaminase (ast) or alanine aminotransferase (alt) >4x the upper limits of normal or as per clinical judgment. 7. hemoglobin <7 g/dl; white blood cell count ≤2,000/mm3 (≤2.0 x 109/l) or ≥20,000/mm3 (≥20 x 109/l); platelet count ≤ 40,000/μl (≤40 x 109/l); absolute neutrophil count ≤1 x 109/l; lymphocyte count <0.3 x 109/l at screening or as per clinical judgment. 8. unstable (as per clinical judgment) major cardiovascular, renal, endocrine, immunological, or hepatic disorder. 9. egfr <25 ml/ min/ 1.73 m2 or as per clinical judgment. 10. plasma and/or serum glucose >300 or as per clinical judgment. 11. cystatin c >3x upper limit of normal or as per clinical judgment. 12. human immunodeficiency virus infection. 13. known active hepatitis b or c infection. 14. invasive fungal infection. 15. uncontrolled (as per clinical judgment) pleural/pericardial effusions or ascites. 16. new/active invasive cancer except non-melanoma skin cancers as per clinical judgment. 17. known condition associated with major immunodeficiency as per clinical judgment. 18. known hypersensitivity or allergy to fisetin. 19. subjects taking any of the medications listed in protocol appendix 1 may participate if they are otherwise eligible and the medication can be safely held during the following times: - immediately before the 1st ip administration (day 0) until at least 10 hours after the 2nd ip administration (day 1) - immediately before the 3rd ip administration (day 8) until at least 10 hours after the 4th ip administration (day 9) 20. participation in other clinical trials involving treatment for covid-19. note that institutional standard of care treatment of covid-19 including glucocorticoids, hydroxychloroquine, azithromycin, remdesivir, anti-spike antibodies, and/or convalescent plasma are not excluded from the study.