WHO recommends prompt recognition of progressive acute hypoxaemic respiratory failure when a patient with respiratory distress is failing to respond to standard oxygen therapy and adequate preparation to provide advanced oxygen/ventilatory support. Hypoxaemic respiratory failure in ARDS commonly results from intrapulmonary ventilation-perfusion mismatch or shunt and usually requires mechanical ventilation. At any time, if there are urgent or emergent indications for intubation, do not delay. WHO suggests that hospitalized patients with severe or critical COVID-19 with acute hypoxaemic respiratory failure that do not require emergent intubation be treated with HFNO, or CPAP or NIV (BiPAP) rather than standard oxygen therapy.