The only known study evaluating SARS development in hospital workers was a retrospective study conducted prior to the widespread use of HFNC showing that development of SARS occurred in tracheal intubation (35%), HFNC 8%, and 38% (NIPPV) 3; this suggests that both non-invasive (including HFNC) and invasive ventilation approaches carry significant risk. ...since the data regarding transmission are unclear, we suggest, in addition to a negative pressure room, reverse isolation protection efforts with patients on HFNC wearing a mask over the nasal interface or a contained respiratory hood. 1. Comparison of high-flow nasal cannula versus oxygen face mask for environmental bacterial contamination in critically ill pneumonia patients: a randomized controlled crossover trial.