I think there is more to the ContactTracing app then what Schneier mentioned.
Understand how to define a close-contact of infected. It requires a constant 30 minutes Bluetooth-strong-signal (geographically near) to the infected person, not just because your "ID" being captured on the infected person.
The app helps find these close-contacts around you and eventually notifying them to isolate themselves and test. Imagine this process chained.
Of course, this will need a scale of people downloading the app. But better-having this auto-logged than human-effort asking infected 1 by 1 (10,000+++ infected VS 100 contact-tracer)!
Understand how to define a close-contact of infected. It requires a constant 30 minutes Bluetooth-strong-signal (geographically near) to the infected person, not just because your "ID" being captured on the infected person.
The app helps find these close-contacts around you and eventually notifying them to isolate themselves and test. Imagine this process chained.
Of course, this will need a scale of people downloading the app. But better-having this auto-logged than human-effort asking infected 1 by 1 (10,000+++ infected VS 100 contact-tracer)!