Are they any use? With Europe’s black-box coronavirus apps it’s hard to tell

In Switzerland, for example, the Federal Office of Public Health acknowledged that 'the effectiveness of the SwissCovid App is difficult to measure' because of its emphasis on 'privacy by design’. — Reuters

DUBLIN/BERLIN: Europe’s experiment in using technology to fight coronavirus has achieved some early successes: millions of people have downloaded smartphone tracker apps and hundreds have uploaded the results of positive Covid-19 tests.

Yet most European countries so far lack solid evidence that their apps – which identify close contacts via Bluetooth connections with nearby users – are actually alerting people who may have caught the disease before they can infect others.