1. prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr \<15 ml/min 3. all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. 6. neutropenia (absolute neutrophil count \<700 cells/microliter, 0.7 x 10\^3/microliter). 7. lymphopenia (absolute lymphocyte count \<200 cells/microliter, 0.20 x 10\^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin \[ivig\] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: * more than one dose of baricitinib for the treatment of covid-19; * other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); * monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 \[il-1\], anti-il-6 \[tocilizumab or sarilumab\], etc.); * monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary 13. use of probenecid that cannot be discontinued at study enrollment. 14. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received \> / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for \> / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. 19. had a known venous thromboembolism (vte)(deep vein thrombosis \[dvt\] or pulmonary embolism \[pe\]) during the current covid-19 illness.

1. prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr \<15 ml/min 3. all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. 6. neutropenia (absolute neutrophil count \<700 cells/microliter, 0.7 x 10\^3/microliter). 7. lymphopenia (absolute lymphocyte count \<200 cells/microliter, 0.20 x 10\^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin \[ivig\] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: * more than one dose of baricitinib for the treatment of covid-19; * other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); * monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 \[il-1\], anti-il-6 \[tocilizumab or sarilumab\], etc.); * monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary 13. use of probenecid that cannot be discontinued at study enrollment. 14. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received \> / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for \> / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. 19. had a known venous thromboembolism (vte)(deep vein thrombosis \[dvt\] or pulmonary embolism \[pe\]) during the current covid-19 illness.

prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. positive test for influenza virus during the current illness (influenza testing is not required by protocol). subjects with a low glomerular filtration rate (egfr), specifically: subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. all subjects with an egfr <15 ml/min all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). allergy to any study medication. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. received any of the following in the two weeks prior to screening as treatment of covid-19: more than one dose of baricitinib for the treatment of covid-19; other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary use of probenecid that cannot be discontinued at study enrollment. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. received > / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. had a known venous thromboembolism (vte)(deep vein thrombosis [dvt] or pulmonary embolism [pe]) during the current covid-19 illness.

prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. positive test for influenza virus during the current illness (influenza testing is not required by protocol). subjects with a low glomerular filtration rate (egfr), specifically: subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. all subjects with an egfr <15 ml/min all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). allergy to any study medication. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. received any of the following in the two weeks prior to screening as treatment of covid-19: more than one dose of baricitinib for the treatment of covid-19; other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary use of probenecid that cannot be discontinued at study enrollment. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. received > / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. had a known venous thromboembolism (vte)(deep vein thrombosis [dvt] or pulmonary embolism [pe]) during the current covid-19 illness.

1. prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr <15 ml/min 3. all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. 6. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). 7. lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: - more than one dose of baricitinib for the treatment of covid-19; - other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); - monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); - monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary 13. use of probenecid that cannot be discontinued at study enrollment. 14. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received > / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. 19. had a known venous thromboembolism (vte)(deep vein thrombosis [dvt] or pulmonary embolism [pe]) during the current covid-19 illness.

1. prior enrollment in actt-3 or actt-4. note: this includes subjects whose participation in actt was terminated early. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 15-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr <15 ml/min 3. all subjects on hemodialysis and/or hemofiltration at screening, irrespective of egfr are excluded. 6. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). 7. lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: - more than one dose of baricitinib for the treatment of covid-19; - other small molecule tyrosine kinase inhibitors (e.g. imatinib, gefitinib, acalabrutinib, etc.); - monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); - monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. note: receipt of anti-sars-cov-2 monoclonal antibody (mab) prior to enrollment (e.g. bamlanivimab) for their current covid-19 illness is not exclusionary 13. use of probenecid that cannot be discontinued at study enrollment. 14. received 6 mg or more of dexamethasone by mouth (po) or intravenous (iv) (or equivalent for other glucocorticoids) in one day, on more than one day, in the 7 days prior to time of randomization. note: 6 mg dexamethasone dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received > / = 20 mg/day of prednisone po or iv (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations including sars-cov-2 vaccine is allowed for all subjects. 19. had a known venous thromboembolism (vte)(deep vein thrombosis [dvt] or pulmonary embolism [pe]) during the current covid-19 illness.

1. prior enrollment in actt-3 or actt-4. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 20-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr <20 ml/min (including hemodialysis and hemofiltration) are excluded. 6. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). 7. lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: - small molecule tyrosine kinase inhibitors (e.g. baricitinib, imatinib, gefitinib, acalabrutinib, etc.); - monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); - monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. 13. use of probenecid that cannot be discontinued at study enrollment. 14. received more than one dose of dexamethasone 6 mg or larger (or equivalent for other glucocorticoids) in the 7 days prior to time of randomization. note: total daily dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received > / = 20 mg/day of prednisone (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations is allowed for all subjects.

1. prior enrollment in actt-3 or actt-4. 2. on invasive mechanical ventilation at the time of randomization (ordinal scale category 7). 3. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of randomization. 4. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 5. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with an egfr 20-30 ml/min are excluded unless in the opinion of the pi, the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with an egfr <20 ml/min (including hemodialysis and hemofiltration) are excluded. 6. neutropenia (absolute neutrophil count <700 cells/microliter, 0.7 x 10^3/microliter). 7. lymphopenia (absolute lymphocyte count <200 cells/microliter, 0.20 x 10^3/microliter). 8. received five or more doses of remdesivir including the loading dose, outside of the study as treatment for covid-19. 9. pregnancy or breast feeding (lactating women who agree to discard breast milk from day 1 until two weeks after the last study product is given are not excluded). 10. allergy to any study medication. 11. received convalescent plasma or intravenous immunoglobulin [ivig] for covid-19, the current illness for which they are being enrolled. 12. received any of the following in the two weeks prior to screening as treatment of covid-19: - small molecule tyrosine kinase inhibitors (e.g. baricitinib, imatinib, gefitinib, acalabrutinib, etc.); - monoclonal antibodies targeting cytokines (e.g., tnf inhibitors, anti-interleukin-1 [il-1], anti-il-6 [tocilizumab or sarilumab], etc.); - monoclonal antibodies targeting t-cells or b-cells as treatment for covid-19. 13. use of probenecid that cannot be discontinued at study enrollment. 14. received more than one dose of dexamethasone 6 mg or larger (or equivalent for other glucocorticoids) in the 7 days prior to time of randomization. note: total daily dose equivalents include 40 mg prednisone, 32 mg methylprednisolone and 160 mg hydrocortisone. 15. received > / = 20 mg/day of prednisone (or equivalent for other glucocorticoids) for > / = 14 consecutive days in the 4 weeks prior to screening. 16. have diagnosis of current active or latent tuberculosis (tb), if known, treated for less than 4 weeks with appropriate therapy (by history only, no screening required). 17. serious infection (besides covid-19), immunosuppressive state, or immunosuppressive medications that in the opinion of the investigator could constitute a risk when taking baricitinib or dexamethasone. 18. have received any live vaccine (that is, live attenuated) within 4 weeks before screening, or intend to receive a live vaccine (or live attenuated) during the study. note: use of non-live (inactivated) vaccinations is allowed for all subjects.