Inclusion Criteria:  Age ≥18 years Positive SARS-CoV-2 test by PCR (polymerase chain reaction) or other diagnostic method within the past 7 days Admission to hospital with respiratory symptoms of COVID-19 requiring hospital care and oxygen supplementation (≤ 8L/min) Respiratory symptom onset no more than 7 days prior to hospital arrival Informed consent from the subject or the subject's personal legal representative or a professional legal representative must be available  Exclusion Criteria:  Unable to screen, randomize and administer study drug within 48 hours from arrival to hospital Systemic corticosteroid, baricitinib or tofacitinib (or other JAK-STAT signalling pathway inhibitors) therapy within 7 days prior to arrival to hospital or planned for the next days Known hypersensitivity or contraindication to natural or recombinant IFN-beta-1a or its excipients, or to dexamethasone or its excipients Currently receiving IFN-beta-1a therapy Home assisted ventilation (via tracheotomy or non-invasive) except for Continuous Positive Airway Pressure (CPAP) / Bilevel Positive Airway Pressure (BIPAP) used only for sleep-disordered breathing Participation in another concurrent interventional pharmacotherapy trial during the study period Decision to withhold life-sustaining treatment; patient not committed to full support (except DNR after cardiac arrest only) Woman known to be pregnant, lactating or with a positive pregnancy test (urine or serum test) Subject is not expected to survive for 24 hours Subject has liver failure (Child-Pugh grade C) Any clinical condition that in the opinion of the attending clinician or Investigator would present a risk for the subject to participate in the study