This is where the CEOsys project, a consortium of 18 German university hospitals and other partners funded by the Network University Medicine from September 2020 to December 2021, came in. The COVID-19evidence ecosystemreviewed the results of scientific studies worldwide on the most pressing issues relating to the prevention, treatment and consequences of COVID-19, evaluated them and summarised them in evidence syntheses. This synthesised evidence was used to derive specific recommendations for action and guidelines on which medicine, politics and the general public could base their decisions. The CEOsys concept also included communicating the knowledge gained to various target groups.