According to the Chinese Centre for Disease Control and Prevention [2], among 72 314 reported cases in mainland China (44 672 confirmed cases, 16 186 suspected cases, 10 567 clinically diagnosed cases, and 889 asymptomatic infected cases) as of 11 February, 1716 medical staff were infected. Notably, Wang et al. [3] analysed the clinical characteristics of 138 hospitalised cases with COVID-19 and found that the nosocomial infection rate in the study was about 41.3%, with 17 inpatients and 40 medical staff. Given the high use of respiratory support to treat dyspnoea and respiratory failure induced by COVID-19, viral transmission through exhaled air should be considered.