inclusion criteria: - adults of 18 years or older - patients hospitalized with a diagnosis of covid-19 based on central laboratory-confirmed covid-19 novel coronavirus disease-2019, based on a positive sars-cov-2 rt-pcr confirmed within 72 hours prior to enrollment of nasal, oropharyngeal, or bal specimen with hypoxemia, (i.e., decrease in oxygenation, as outlined below) - pulse oximetry saturation (spo2) < 93% on room air in who covid-19 ordinal scale 3 patients, regardless the need for assisted ventilation, or oxygenation. - any new requirement of supplemental oxygen, with any oxygen device (who covid-19 ordinal scale 4-7, regardless of pulse oximetry reading) - in patients with supplemental oxygen at home, any increase in the requirement of supplemental oxygen.

inclusion criteria: - adults of 18 years or older - patients hospitalized with a diagnosis of covid-19 based on central laboratory-confirmed covid-19 novel coronavirus disease-2019, based on a positive sars-cov-2 rt-pcr confirmed within 72 hours prior to enrollment of nasal, oropharyngeal, or bal specimen with hypoxemia, (i.e., decrease in oxygenation, as outlined below) - pulse oximetry saturation (spo2) < 93% on room air in who covid-19 ordinal scale 3 patients, regardless the need for assisted ventilation, or oxygenation. - any new requirement of supplemental oxygen, with any oxygen device (who covid-19 ordinal scale 4-7, regardless of pulse oximetry reading) - in patients with supplemental oxygen at home, any increase in the requirement of supplemental oxygen.

inclusion criteria: - patients hospitalized with a diagnosis of covid-19 based on positive rt-pcr of nasal, oropharyngeal, or bal specimen with hypoxemia, (i.e., decrease in oxygenation, as outlined below) - new pulse oximetry saturation < 93% on room air or - any new requirement of supplemental oxygen, with any device - in patients with supplemental oxygen at home, any increase in the requirement of supplemental oxygen.

inclusion criteria: - patients hospitalized with a diagnosis of covid-19 based on positive rt-pcr of nasal, oropharyngeal, or bal specimen with hypoxemia, (i.e., decrease in oxygenation, as outlined below) - new pulse oximetry saturation < 93% on room air or - any new requirement of supplemental oxygen, with any device - in patients with supplemental oxygen at home, any increase in the requirement of supplemental oxygen.