1. Proportion of clinical recovery (composite) within 14 & 21 days (Normalization of fever (=37.2 °C oral); Respiratory rate (=24/minute on room air); Oxygen saturation (=94% on room air)); sustained for at least 24 hours (using Exact test with Boot-Strapping). 2. Time to clinical recovery (composite) [Time frame: 21 days after randomization (using Kaplan Meier curve and Cox-regression). 3. Time to viral negativity assessed twice 48 hours apart (log10 viral load assessed by reverse transcription-PCR) during hospital stay (Kaplan Meier curve and Cox-regression).4. Mean change in Clinical status using 8 point ordinal scale [Day 3 through Day 14; 21 (using Repeated measure Factorial ANOVA test]: 1) Death; 2) Hospitalized; on invasive ventilation or ECMO; 3) Hospitalized; on NIV or HFO2; 4) Hospitalized with oxygen supplement; 5) Hospitalized; not requiring oxygen but need medical care; 6) Hospitalized; not requiring supplemental oxygen or ongoing medical care; 7) Not hospitalized; limitation on activities and/or requiring home oxygen; 8) Not hospitalized with normal activity.

1. Proportion of clinical recovery (composite) within 14 & 21 days (Normalization of fever (=37.2 °C oral); Respiratory rate (=24/minute on room air); Oxygen saturation (=94% on room air)); sustained for at least 24 hours (using Exact test with Boot-Strapping). 2. Time to clinical recovery (composite) [Time frame: 21 days after randomization (using Kaplan Meier curve and Cox-regression). 3. Time to viral negativity assessed twice 48 hours apart (log10 viral load assessed by reverse transcription-PCR) during hospital stay (Kaplan Meier curve and Cox-regression).4. Mean change in Clinical status using 8 point ordinal scale [Day 3 through Day 14; 21 (using Repeated measure Factorial ANOVA test]: 1) Death; 2) Hospitalized; on invasive ventilation or ECMO; 3) Hospitalized; on NIV or HFO2; 4) Hospitalized with oxygen supplement; 5) Hospitalized; not requiring oxygen but need medical care; 6) Hospitalized; not requiring supplemental oxygen or ongoing medical care; 7) Not hospitalized; limitation on activities and/or requiring home oxygen; 8) Not hospitalized with normal activity.