Back to Blog

Virus variants in the Corona-Warn-App

Robin Houben, on July 8, 2021

With regard to the newly emerging "variants of concern" (VoC), in particular the delta variant in Germany, the Project Team of the Corona-Warn-App is continuously monitoring possible adaptions of the performance of the app to the current circumstances. In this context, discussions on adapting the risk calculation continue to take place between the project participants from the Robert Koch Institute, the Deutsche Telekom, SAP and the Fraunhofer Institute for Integrated Circuits IIS.

At this point in time, the scientific evidence is not yet sufficient to make a change to the risk calculation. Various data sources are regularly evaluated to assess the current situation and are included in the decision-making process. The Project Team is following the recommendations for action for the "analog" contact tracing of the public health authorities in the risk calculation in the Corona-Warn-App. As soon as there are changes here, the risk calculation in the Corona-Warn-App will also be adapted.

At least nine minutes

Currently, an encounter with a person testing positive for SARS-CoV-2 must have been measured for at least 9 weighted minutes in a defined proximity area to be considered by the app as an encounter with increased risk ("red tile").

The adjustment of the parameters is done server-sided, so users do not have to do anything here. As soon as there will be a new adjustment, the project team will inform about changes on the blog and on Twitter (