Covid-19 ContacTUM | ndm

The Covid-19 ContacTUM initiative

The Covid-19 ContacTUM initiative started in mid-March 2020, literally on the first day of the Government's corona lockdown. The SFB1258 scientists around Elisa Resconi asked themselves what they could do to help fight the emerging corona pandemic. They started developing the concept for a Covid-19 Exposure Notification System, at a time when no one ever heard of a "Corona App". In parallel, a second activity developed around Stefan Schönert and Tina Pollmann with the goal of setting up an epidemiological model for simulating the effect of an app and other non-pharmaceutical mitigation measures with Monte Carlo methods. To achieve these goals, an interdisciplinary group of scientists from the SFB1258, the TUM Faculties of Mathematics, Physics and Computer Science and the TUM Schools of Medicine and Governance formed under the name of ContacTUM Consortium.

Development of a Bluetooth-based Esposure Notification System with privacy by design

The prime concern of the app-team was to ensure by design the maximum data security and privacy because the team anticipated that the efficacy such an app could achieve would primarily depend on the people's trust and acceptance in the tool. Thus, they focused on a Bluetooth-based contact tracing system, that performs the matching between users who have the disease and their contacts on the non-infected users’ phones. This approach was discussed as the "decentralised" version as opposed to the centralised, where the match is done on a central server.

For the app, a collaboration with ITO evolved, a group of German professionals that joined to develop an open source contact tracing system. The ContacTUM team also got a member of the international TCN coalition, a community of technologists supporting privacy-preserving exposure notification apps during the Covid-19 pandemic.

Concept submitted to Bluetooth

The novel coronavirus, named Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). (Illustration: CDC/Alissa Eckert, MS, Dan Higgins, MAMS)

The ContacTUM & ITO Consortia submitted their concept for review to the Bluetooth Special Interest Group (Bluethooth SIG) on 7 April 2020. While the German Government initially favored the centralised over the decentralised approach for the German Corona app, a joint statement of international scientists was released on 19 April 2020 that urged countries "to rely only on systems that are subject to public scrutiny and that are privacy preserving by design". The statement was signed by the TUM scientists Prof. Christian Djeffal, Dr. Tina Pollmann, Prof. Elisa Resconi and Prof. Stefan Schönert, all of them engaged in the ContacTUM Consortium.

A prototype app was made available

A prototype app for android devices based on the ContacTUM & ITO concept was made avaible as a download on the ITO website in May 2020. Shortly therafter, the publication that describes the principles of the ContacTUM & ITO exposure notification system "Digital Contact Tracing Service: An improved decentralized design for privacy and effectiveness" was put on GitHub and submitted for publication. The concept includes the encryption technology Private Set Intersection Cardinality for improved privacy and second order tracing of contact persons. Detailed information on the DCTS app can be found on the following pages, including information on other DCTS/ENS approaches. In June 2020, the official German Corona-warn-app following the central approach was finally released.