1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin \<8 g/dl). 8. absolute lymphocyte count \<500 cells/mm; 9. absolute neutrophil count \<1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone \>20 mg/day for equal or more than 14 consecutive days prior to screening. 16. current participation in other trials.

1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin \<8 g/dl). 8. absolute lymphocyte count \<500 cells/mm; 9. absolute neutrophil count \<1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone \>20 mg/day for equal or more than 14 consecutive days prior to screening. 16. current participation in other trials.

require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. have a personal or first-degree family history of blood clotting disorders. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). participants with any current malignancy or lymphoproliferative disorders that requires active treatment severe hepatic impairment, defined as child-pugh class c. severe anemia (hemoglobin <8 g/dl). absolute lymphocyte count <500 cells/mm; absolute neutrophil count <1000 cells/mm. known allergy to tofacitinib. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening. current participation in other trials.

require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. have a personal or first-degree family history of blood clotting disorders. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). participants with any current malignancy or lymphoproliferative disorders that requires active treatment severe hepatic impairment, defined as child-pugh class c. severe anemia (hemoglobin <8 g/dl). absolute lymphocyte count <500 cells/mm; absolute neutrophil count <1000 cells/mm. known allergy to tofacitinib. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening. current participation in other trials.

1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin <8 g/dl). 8. absolute lymphocyte count <500 cells/mm; 9. absolute neutrophil count <1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening. 16. current participation in other trials.

1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin <8 g/dl). 8. absolute lymphocyte count <500 cells/mm; 9. absolute neutrophil count <1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening. 16. current participation in other trials.

1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin <8 g/dl). 8. absolute lymphocyte count <500 cells/mm; 9. absolute neutrophil count <1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening.

1. require non-invasive ventilation, invasive mechanical ventilation, or extracorporeal membrane oxygenation (ecmo) on day 1 at the time of randomization 2. history of or known current thrombosis. only if current thrombosis is suspected by the investigator, imaging testing is recommended (per local guidance) to exclude thrombosis. 3. have a personal or first-degree family history of blood clotting disorders. 4. participants who are immunocompromised, with known immunodeficiencies, or taking potent immunosuppressive agents (eg, azathioprine, cyclosporine). 5. participants with any current malignancy or lymphoproliferative disorders that requires active treatment 6. severe hepatic impairment, defined as child-pugh class c. 7. severe anemia (hemoglobin <8 g/dl). 8. absolute lymphocyte count <500 cells/mm; 9. absolute neutrophil count <1000 cells/mm. 10. known allergy to tofacitinib. 11. other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk associated with study participation or, in the investigator's judgment, make the participant inappropriate for the study. 12. suspected or known active systemic bacterial, fungal, or viral infections (with the exception of covid-19) including but not limited to: active herpes zoster infection; known active tuberculosis or history of inadequately treated tuberculosis; known b hepatitis, c hepatitis, or hiv. 13. have received any of these within 4 weeks prior to the first dose of study intervention: any jak inhibitors, potent immunosuppressants, or any biologic agents including il-6 inhibitors (eg, tocilizumab) or il-1 inhibitors (eg, anakinra) within the past 30 days; any potent cytochrome p450 inducer, such as rifampin, within the past 28 days or 5 half-lives, whichever is longer. 14. have received estrogen-containing contraception or treatment with herbal supplements within 48 hours prior to the first dose of study intervention. 15. have received treatment with corticosteroids equivalent to prednisone or methylprednisolone >20 mg/day for equal or more than 14 consecutive days prior to screening.