inclusion criteria: * patients ≥18 years of age * hospitalized with covid-19-related acute respiratory symptoms * initial covid-19 severity status on the who ordinal scale for clinical improvement = 3 ("hospitalized, no oxygen therapy) or 4 ("hospitalized, on oxygen by mask or nasal prongs") * laboratory-confirmed covid-19 * first signs of infection occurring no more than 14 days prior to enrollment

inclusion criteria: * patients ≥18 years of age * hospitalized with covid-19-related acute respiratory symptoms * initial covid-19 severity status on the who ordinal scale for clinical improvement = 3 ("hospitalized, no oxygen therapy) or 4 ("hospitalized, on oxygen by mask or nasal prongs") * laboratory-confirmed covid-19 * first signs of infection occurring no more than 14 days prior to enrollment

inclusion criteria: - patients ≥18 years of age - hospitalized with covid-19-related acute respiratory symptoms - initial covid-19 severity status on the who ordinal scale for clinical improvement = 3 ("hospitalized, no oxygen therapy) or 4 ("hospitalized, on oxygen by mask or nasal prongs") - laboratory-confirmed covid-19 - first signs of infection occurring no more than 14 days prior to enrollment

inclusion criteria: - patients ≥18 years of age - hospitalized with covid-19-related acute respiratory symptoms - initial covid-19 severity status on the who ordinal scale for clinical improvement = 3 ("hospitalized, no oxygen therapy) or 4 ("hospitalized, on oxygen by mask or nasal prongs") - laboratory-confirmed covid-19 - first signs of infection occurring no more than 14 days prior to enrollment