In this Bayesian analysis of the COVID STEROID 2 trial, we found relatively high posterior probabilities of benefit with dexamethasone 12 mg versus 6 mg in patients with COVID-19 and severe hypoxaemia on all outcomes, including the days alive without life support and mortality at day 28 and 90. We found relatively low probabilities of clinically important harm with 12 mg dexamethasone for all outcomes.