This is vital if we are to move past coronavirus. It took longer than it should have to make this available, but everyone has a responsibility to install the app for their specific country. (The privacy solution is very clever. The most common criticism is health departments complaining that they want more information so they can trace outbreaks.)
It's a fairly good design, but I don't think it has proven very effective so far, at least in Switzerland, as the installed base is not large enough to make much of an impact.