Very interesting, the publication by European privacy authority EDPS on contact tracing with mobile applications. EDPS says that there are major data protection risks:

Digital proximity tracing raises novel data protection risks as it provides for preventive, contact recording of a very large number of the population in public and private spaces using radio wave signals invisible to human eyes.
Contact tracing applications are therefore likely to result in a high risk to the rights and freedoms of natural persons and to require a data protection impact assessment to be conducted prior to their deployment.

The recommendations show that governments should assess very thoroughly if their corona-apps fulfil all requirements.

Hoepman: GACT is a wolf in sheep’s clothes
Another bottleneck is that the mobile operating systems (iOS and android) have to be adapted. Google and Apple work together on that in the Google Apple Contact Tracting (GACT) project.

Jaap Henk Hoepman on 19 April 2020 wrote a critical article, “Google Apple Contact Tracing (GACT): a wolf in sheep’s clothes“. He explains that the adaptation of the operating systems will be permanent and the tracing functionality will also work when no corona-app has been installed. He concludes:

This (technically) creates a dormant functionality for mass surveillance

It may endanger the security of all mobile phone users and will make the world more dependant on the two internet giants.