address the main end-point, and the articles, which analyzed responders and
nonresponders in the prone position. We also considered articles, which compared COVID
and non-COVID patients in whom prone position was used. Indeed, it has been claimed that
the pathophysiology of COVID-19-related acute respiratory syndrome (ARDS) may be
different from the classic ARDS [10▪,11,12▪▪] , casting some doubt about the usefulness of …