A man shows the contact tracing app Stayaway Covid on his cellphone, in Lisbon, Thursday, Sept. 17, 2020. Mobile apps tracing new COVID cases were touted as a key part of Europes plan to beat the coronavirus outbreak. (AP Photo/Armando Franca)LONDON – Mobile apps tracing new COVID-19 cases were touted as a key part of Europe’s plan to beat the coronavirus outbreak. Public trust in the government helps allay concerns about privacy and government surveillance first raised when some countries launched tracing apps months earlier. We might never know for sure, said Stephen Farrell, a computer scientist at Trinity College Dublin who has studied tracing apps.