Changes in the epidemiology of ventilator-associated events over the course of the coronavirus disease 2019 (COVID-19) pandemic.

Management of critically ill coronavirus disease 2019 (COVID-19) patients has evolved considerably during the pandemic. We investigated rates and causes of ventilator-associated events (VAEs) in COVID-19 patients in the late versus early waves in 4 Massachusetts hospitals. VAE rates per episode decreased, rates per ventilator day were stable, and most cases were caused by acute respiratory distress syndrome (ARDS).