inclusion criteria: * age ≥18 years old * admitted to hospital ward or icu * a positive pcr test for sars-cov-2 from throat swab or nasopharynx * an oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen * signed informed consent

inclusion criteria: * age ≥18 years old * admitted to hospital ward or icu * a positive pcr test for sars-cov-2 from throat swab or nasopharynx * an oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen * signed informed consent

inclusion criteria: - age ≥18 years old - admitted to hospital ward or icu - a positive pcr test for sars-cov-2 from throat swab or nasopharynx - an oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen - signed informed consent

inclusion criteria: - age ≥18 years old - admitted to hospital ward or icu - a positive pcr test for sars-cov-2 from throat swab or nasopharynx - an oxygen saturation ≤90% after maximum 15 minutes without supplemental oxygen - signed informed consent