Main Study: All the following criteria need to be met for inclusion: 1. Men and women ≥18 years of age at the time of consent. 2. Laboratory-confirmed diagnosis of COVID-19. 3. Hospitalized for COVID-19 related respiratory disease. 4. Patient belongs to one of the following four categories in the nine-point COVID-19 severity scale: Hospitalized, not requiring supplemental oxygen –Level 3 of the nine-point COVID-19 severity scale. Hospitalized, requiring supplemental oxygen – Level 4 of the nine-point COVID-19 severity scale. Hospitalized, requiring nasal high-flow oxygen therapy, non-invasive mechanical ventilation, or both – Level 5 of the nine-point COVID-19 severity scale. Hospitalized, requiring intubation and mechanical ventilation- Level 6 of the nine-point COVID-19 severity scale. 5. For women of childbearing potential involved in any sexual intercourse that could lead to pregnancy: Negative pregnancy test and willingness to use contraceptive (consistent with local regulations) during the study period. 6. Informed consent obtained from any patient capable of giving consent, or, when the patient is not capable of giving consent, from his or her legal/authorized representatives. Sub (Exploratory) Study: All the inclusion criteria of the Main Study with the following substitution for inclusion criterion (4): Hospitalized, requiring ventilation for more than 5 days or intubation + additional organ support – pressors, RRT, ECMO - Level 7 of the nine-point COVID-19 severity scale.

Main Study: All the following criteria need to be met for inclusion: 1. Men and women ≥18 years of age at the time of consent. 2. Laboratory-confirmed diagnosis of COVID-19. 3. Hospitalized for COVID-19 related respiratory disease. 4. Patient belongs to one of the following four categories in the nine-point COVID-19 severity scale: Hospitalized, not requiring supplemental oxygen –Level 3 of the nine-point COVID-19 severity scale. Hospitalized, requiring supplemental oxygen – Level 4 of the nine-point COVID-19 severity scale. Hospitalized, requiring nasal high-flow oxygen therapy, non-invasive mechanical ventilation, or both – Level 5 of the nine-point COVID-19 severity scale. Hospitalized, requiring intubation and mechanical ventilation- Level 6 of the nine-point COVID-19 severity scale. 5. For women of childbearing potential involved in any sexual intercourse that could lead to pregnancy: Negative pregnancy test and willingness to use contraceptive (consistent with local regulations) during the study period. 6. Informed consent obtained from any patient capable of giving consent, or, when the patient is not capable of giving consent, from his or her legal/authorized representatives. Sub (Exploratory) Study: All the inclusion criteria of the Main Study with the following substitution for inclusion criterion (4): Hospitalized, requiring ventilation for more than 5 days or intubation + additional organ support – pressors, RRT, ECMO - Level 7 of the nine-point COVID-19 severity scale.