Master Protocol Number: 2.0 dated 1 Nov 2021: Participants are eligible to be included in the study only if all the following general inclusion (GI) criteria apply: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR not more than 14 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5A: Moderate disease state defined as hospitalised patients without oxygen therapy or oxygen by mask or nasal prongs needed, or GI5B: Severe/critical disease state defined as fulfilliing at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = Extracorporeal membrane oxygenation. Additional inclusion criteria are given in the intervention-specific sub-protocols. Baricitinib specific protocol v. 2.0 dated 1 Nov 2021: All participants must be eligible according to the master protocol inclusion criteria (SolidAct Part B). Only the general inclusion criteria (GI) for severe/critical COVID-19 are applicable: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR in any specimen not more than 14 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5B: Severe/critical disease state defined as fulfilling at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = extracorporeal membrane oxygenation. Note: these are based on the same criteria as in the WHO living guidelines recommending corticosteroid treatment for severe and critical COVID-19. In addition, the following specific inclusion criterion applies to immunocompromised patients: SI-01. Immunocompromised patients are eligible only if they have elevation of 2 or more inflammatory markers above the following cutoffs: -Ferritin ≥ 700 ug/l -LDH ≥ 400 U/L -CRP ≥75 mg/dL Immunocompromised patients are defined as the presence of at least one of the following conditions: 1. Hematological malignancy or pre-malignancy, except acute leukemia or history of lymphoma 2. Organ transplant recipients, except recipients of bone marrow or solid organ transplant last 6 months, or with transplant rejection last 6 months 3. HIV positive with CD4 count < 350 cells and on stable antiretroviral therapy 4. Primary immunodeficiency 5. Rheumatoid arthritis, lupus, vasculitis, inflammatory bowel disease or other autoimmune disorder for which a patient is being treated with systemic immunosuppressive medication 6. Other specified cause, such as history of cancer, cancer treatment or other condition that in the opinion of the investigator could cause impaired host immunity Note: Carefully check exclusion criteria SE-01, SE-20 and SE-21 (immunosuppressive therapy), SE-22 (medical condition), SE-13 (neutropenia) and SE-14 (lymphopenia) for eligibility criteria. Immunocompromised patients should receive appropriate SoC, including anti-SARS-CoV2 monoclonal antibodies or emerging antiviral treatment, if available and indicated by current treatment guidelines at time of inclusion.

Master Protocol Number: 2.0 dated 1 Nov 2021: Participants are eligible to be included in the study only if all the following general inclusion (GI) criteria apply: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR not more than 14 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5A: Moderate disease state defined as hospitalised patients without oxygen therapy or oxygen by mask or nasal prongs needed, or GI5B: Severe/critical disease state defined as fulfilliing at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = Extracorporeal membrane oxygenation. Additional inclusion criteria are given in the intervention-specific sub-protocols. Baricitinib specific protocol v. 2.0 dated 1 Nov 2021: All participants must be eligible according to the master protocol inclusion criteria (SolidAct Part B). Only the general inclusion criteria (GI) for severe/critical COVID-19 are applicable: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR in any specimen not more than 14 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5B: Severe/critical disease state defined as fulfilling at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = extracorporeal membrane oxygenation. Note: these are based on the same criteria as in the WHO living guidelines recommending corticosteroid treatment for severe and critical COVID-19. In addition, the following specific inclusion criterion applies to immunocompromised patients: SI-01. Immunocompromised patients are eligible only if they have elevation of 2 or more inflammatory markers above the following cutoffs: -Ferritin ≥ 700 ug/l -LDH ≥ 400 U/L -CRP ≥75 mg/dL Immunocompromised patients are defined as the presence of at least one of the following conditions: 1. Hematological malignancy or pre-malignancy, except acute leukemia or history of lymphoma 2. Organ transplant recipients, except recipients of bone marrow or solid organ transplant last 6 months, or with transplant rejection last 6 months 3. HIV positive with CD4 count < 350 cells and on stable antiretroviral therapy 4. Primary immunodeficiency 5. Rheumatoid arthritis, lupus, vasculitis, inflammatory bowel disease or other autoimmune disorder for which a patient is being treated with systemic immunosuppressive medication 6. Other specified cause, such as history of cancer, cancer treatment or other condition that in the opinion of the investigator could cause impaired host immunity Note: Carefully check exclusion criteria SE-01, SE-20 and SE-21 (immunosuppressive therapy), SE-22 (medical condition), SE-13 (neutropenia) and SE-14 (lymphopenia) for eligibility criteria. Immunocompromised patients should receive appropriate SoC, including anti-SARS-CoV2 monoclonal antibodies or emerging antiviral treatment, if available and indicated by current treatment guidelines at time of inclusion.

Master Protocol Number: 1.1 dated 07 April 2021: Participants are eligible to be included in the study only if all the following general inclusion (GI) criteria apply: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR not more than 9 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5A: Moderate disease state defined as hospitalised patients without oxygen therapy or oxygen by mask or nasal prongs needed, or GI5B: Severe/critical disease state defined as fulfilliing at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = Extracorporeal membrane oxygenation. Additional inclusion criteria are given in the intervention-specific sub-protocols. Baricitinib specific protocol v. 1.1 dated 07 April 2021: All participants must be eligible according to the master protocol inclusion criteria (SolidAct Part B). Only the general inclusion criteria (GI) for severe/critical COVID-19 are applicable: GI1. ≥18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR in any specimen not more than 9 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5B: Severe/critical disease state defined as fulfilling at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = extracorporeal membrane oxygenation.

Master Protocol Number: 1.1 dated 07 April 2021: Participants are eligible to be included in the study only if all the following general inclusion (GI) criteria apply: GI1. ≥ 18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR not more than 9 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5A: Moderate disease state defined as hospitalised patients without oxygen therapy or oxygen by mask or nasal prongs needed, or GI5B: Severe/critical disease state defined as fulfilliing at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = Extracorporeal membrane oxygenation. Additional inclusion criteria are given in the intervention-specific sub-protocols. Baricitinib specific protocol v. 1.1 dated 07 April 2021: All participants must be eligible according to the master protocol inclusion criteria (SolidAct Part B). Only the general inclusion criteria (GI) for severe/critical COVID-19 are applicable: GI1. ≥18 years of age GI2. Laboratory-confirmed SARS-CoV-2 infection (new infection or reinfection) as determined by PCR in any specimen not more than 9 days old GI3. Admitted to hospital GI4. Informed consent by the participant or legally authorized representative. GI5B: Severe/critical disease state defined as fulfilling at least one of the following criteria: 1. SpO2<90% on room air, or 2. SpO2 90-94% with a downwards trend and/or signs of respiratory distress*, or 3. Need of oxygen by NIV (CPAP, BIPAP), high flow or non-rebreather mask, or 4. Need of mechanical ventilation/ECMO *persistently increased respiratory rate, use of accessory muscles, inability to complete full sentences. Clinical judgement must be applied to determine whether a low oxygen saturation is indicative of disease progression or severity or is habitual for a given patient (i.e., with underlying chronic lung disease). NIV=non-invasive ventilation. CPAP= Continuous Positive Airway Pressure, BPAP= Bi-level Positive Airway Pressure, ECMO = extracorporeal membrane oxygenation.