  Context: More than 50 countries have developed COVID contact-tracing apps to
limit the spread of coronavirus. However, many experts and scientists cast
doubt on the effectiveness of those apps. For each app, a large number of
reviews have been entered by end-users in app stores. Objective: Our goal is to
gain insights into the user reviews of those apps, and to find out the main
problems that users have reported. Our focus is to assess the "software in
society" aspects of the apps, based on user reviews. Method: We selected nine
European national apps for our analysis and used a commercial app-review
analytics tool to extract and mine the user reviews. For all the apps combined,
our dataset includes 39,425 user reviews. Results: Results show that users are
generally dissatisfied with the nine apps under study, except the Scottish
("Protect Scotland") app. Some of the major issues that users have complained
about are high battery drainage and doubts on whether apps are really working.
Conclusion: Our results show that more work is needed by the stakeholders
behind the apps (e.g., app developers, decision-makers, public health experts)
to improve the public adoption, software quality and public perception of these
apps.
