Randomized controlled trials (RCTs) and observational studies comparing corticosteroids versus no corticosteroids in patients with COVID-19, severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS). For acute respiratory distress syndrome (ARDS), influenza and communityacquired pneumonia (CAP), we updated the most recent rigorous systematic review. Our search for COVID-19, SARS and MERS identified 5120 citations. we ultimately included 1 cohort study including 84 patients with COVID-19 and ARDS, 5 cohort studies including 679 patients with COVID-19 but without ARDS, 3 studies (2 cohort studies and 1 RCT26) including 7087 patients with SARS, and 2 cohort studies including 623 patients with MERS.