Sune Lehmann. Foto: Thorkild Amdi Christensen

New app to detect chains of infection

Thursday 02 Apr 20


Sune Lehmann Jørgensen
DTU Compute
+45 45 25 39 04
Professor Sune Lehmann from DTU Compute is the Danish contributor to a pan-European app aimed at reducing the spread of coronavirus.

Update 28.04: Since this article was published, Sune Lehmann has withdrawn from the project due to disagreement over centralized vs decentralized protocol for privacy. Read more here: 

In recent weeks, 130 researchers from eight European countries and 17 different companies and organizations—including DTU—have been developing a new app which can tell users if they have been in the proximity of a coronavirus carrier.

The project is entitled Pan-European Privacy Preserving Proximity Tracing (PEPP-PT). As the name suggests, complete anonymity is ensured in connection with the tracing. The identity of the infected person is not disclosed to anyone. The only information provided is that you have been in the proximity of a virus carrier.

Full anonymity

Since the coronavirus outbreak, several Asian countries have used similar methods, which have, however, not been sufficiently anonymized. These methods have worked, but have also resulted in invasion of people’s privacy and stigmatization of individuals. And our goal with PEPP-PT is precisely to avoid this, says Professor Sune Lehmann, who is the only Danish project participant:

“In these times of great uncertainty in society, it’s important that we stick to technologies that people feel they can trust and that can consequently support the unity needed. That’s why the challenge we faced in relation to ‘proximity tracing’ was to design an app that doesn't invade people’s privacy.”

The solution works via Bluetooth. The app creates a temporary ID which it exchanges with another user if the distance is sufficiently short. The IDs are encrypted and are only saved locally. If a user tests positive for coronavirus, the doctor may request the person in question to make it possible for others to see that this ID belongs to an infected person. The app will then notify anyone who has been in the proximity of the coronavirus carrier.

Will reduce the spread of infection across Europe

Recipients of the information are not told who the infected person is, where the contact occurred, or when. The message simply advises users of the app that they have been in the proximity of a coronavirus carrier. This ensures full anonymity for everyone—in complete accordance with GDPR. The long-term goal is for the app to work throughout Europe.

“In line with European societies beginning to allow their citizens to move about freely again, there will be a need for solutions that can help trace infected persons and warn those with whom they are in contact—without invading people’s privacy. Some of these solutions can draw on new digital opportunities that can be implemented throughout society and across national borders. Here, one of the most obvious tools is people’s phones because we have them with us everywhere anyway,” says Sune Lehmann.

In his daily work, he conducts research into how people function and communicate in networks—supported by digital technologies. Among other activities, he headed the SensibleDTU project in which 1000 DTU students were equipped with mobile phones monitoring their behaviour in unprecedented detail. He was invited to join the project because of this background, and because several of his former PhD students have unique knowledge of how to protect users’ privacy. For several years, Sune Lehmann has also studied how information flows on, for example, social media—a mechanism that is, to a certain extent, comparable to the spread of viruses.

Hoping for support from the authorities

Sune Lehmann stresses that the app will only really come into its own once societies start opening up again, and people resume their normal lives and activities such as work, teaching, and travel. In this situation, the chains of infection may be reactivated if new cases are not detected and isolated quickly.

The app is not yet available in a Danish version, but Sune Lehmann hopes that the Danish authorities will consider using it in line with an increase in the test capacity and as the situation in society begins to normalize.


Read more about PEPP-PT on the project's webside.

Two corona projects

Sune Lehmann is involved in another corona-related project in which—together with researchers from the University of Copenhagen and Aarhus University—he will contribute to the management of the crisis by means of big data analyses, machine learning, and behavioural psychology, among other methods. The research will help us understand the connections between the government’s handling of the crisis, media coverage, the population’s behaviour, and spread of the virus. The project is supported by the Carlsberg Foundation with DKK 25 million. 

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