Inclusion Criteria:  All mechanical ventilated patients registered in the national Danish COVID ICU database between 10.03.2020 - 02.04.2021 i.e.  Admitted to an ICU in Denmark Laboratory-confirmed SARS-CoV-2 infection Use of invasive mechanical ventilation (ventilation via a cuffed endotracheal tube) at any time during the ICU stay  Exclusion Criteria:  None