1.Age ≥18 years old. 2.Admitted to hospital ward or ICU. 3.A positive PCR test for SARS-CoV-2 from throat swab or nasopharynx. 4.An oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen. 5.Signed informed consent.

1.Age ≥18 years old. 2.Admitted to hospital ward or ICU. 3.A positive PCR test for SARS-CoV-2 from throat swab or nasopharynx. 4.An oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen. 5.Signed informed consent.