1. Admitted to a hospital with a diagnosis of moderate or severe COVID-19 pneumonia defined as: a. moderate cases: showing fever and respiratory symptoms with radiological findings of pneumonia, b. severe cases meeting any of the following criteria: i) respiratory distress (≧30 breaths/ min), ii) oxygen saturation≤93% at rest without oxygen inhalation, iii) PaO2/FiO2(fraction of inspired oxygen)≤300mmHg, iv) with chest imaging that showed obvious lesion progression within 24-48 hours >50% shall be managed as severe cases 2. Subject, or legally authorized representative, provides written informed consent prior to the initiation of any study procedures. 3. Understands and agrees to comply with planned study procedures. 4. Agrees to the collection of oropharyngeal swabs. 5. Male or non-pregnant female adult > / = 18 years of age at the time of enrollment. 6. Has laboratory-confirmed SARS-CoV-2 infection as determined by polymerase chain reaction (PCR) or other commercial or public health assay in any specimen collected < 72 hours prior to randomization. Note, 72 hours is not necessarily time from initial diagnosis. If > / = 72 hours since positive PCR, the PCR may be repeated to assess eligibility. 7. Women of childbearing potential must agree to either abstinence or use at least one primary form of contraception not including hormonal contraception from the time of screening through Day 29.

1. Admitted to a hospital with a diagnosis of moderate or severe COVID-19 pneumonia defined as: a. moderate cases: showing fever and respiratory symptoms with radiological findings of pneumonia, b. severe cases meeting any of the following criteria: i) respiratory distress (≧30 breaths/ min), ii) oxygen saturation≤93% at rest without oxygen inhalation, iii) PaO2/FiO2(fraction of inspired oxygen)≤300mmHg, iv) with chest imaging that showed obvious lesion progression within 24-48 hours >50% shall be managed as severe cases 2. Subject, or legally authorized representative, provides written informed consent prior to the initiation of any study procedures. 3. Understands and agrees to comply with planned study procedures. 4. Agrees to the collection of oropharyngeal swabs. 5. Male or non-pregnant female adult > / = 18 years of age at the time of enrollment. 6. Has laboratory-confirmed SARS-CoV-2 infection as determined by polymerase chain reaction (PCR) or other commercial or public health assay in any specimen collected < 72 hours prior to randomization. Note, 72 hours is not necessarily time from initial diagnosis. If > / = 72 hours since positive PCR, the PCR may be repeated to assess eligibility. 7. Women of childbearing potential must agree to either abstinence or use at least one primary form of contraception not including hormonal contraception from the time of screening through Day 29.