Severe COVID-19 illness is characterised by the development of Acute Respiratory Distress Syndrome (ARDS), for which the mainstay of treatment is represented by mechanical ventilation. Mortality associated with ARDS due to other causes is in the range of 40-60%, but currently available data are not yet sufficient to draw safe conclusions on the prognosis of COVID-19 patients who require mechanical ventilation. Based on data from cohorts of the related coronavirus-associated illnesses, that is to say Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), prognosis would seem to be worse than ARDS due to other causes such as trauma and other infections. Discussion of prognosis is central to obtaining informed consent for intubation, but in the absence of definitive data it is not clear exactly what this discussion should entail.