The Corona-Warn-App's project team continuously improves the app's performance with regard to the coronavirus situation in Germany. In response to virus mutations, the team members from the Robert Koch-Institut, Deutsche Telekom, SAP and the Fraunhofer Institute for Integrated Circuits (IIS) have therefore further improved the risk calculation and reduced the duration of a critical encounter from 13 minutes to 9 minutes.
For app users, this means: Previously, an encounter between two people had to last at least 13 minutes in order to be considered for an encounter with an increased risk (red tile). Now, the app considers encounters of at least 9 minutes. Thus, encounters that represent an actual relevant contact with COVID-19 infected persons can be detected even more accurately and represented accordingly in the app as a warning about an encounter with increased risk. This increases the number of warnings by approximately 16 percent. The parameters are adjusted on the server. Users don't have to do anything.
Most recently, the project team adjusted the risk calculation at the end of March in response to a virus mutation. It continues to work on improving the measurements and the resulting configuration parameters.