Italy Tests Contact-Tracing App to Speed Lockdown Exit
nytimes.comApparently 60% of the population should use these apps in order for them to be effective, which turns into 80% of smartphone users.
In Singapore the uptake of the TraceTogether app has only been 12%of the population, and the city ended up in lockdown anyway.
Making those apps opt-in, i.e. optional, is taking a big risk. At the same time deploying a system that works at such scale in such short time isn't easy.