I was lucky enough to get out Hong Kong before COVID-19 locked up air travel. Not sure that I'll be going back anytime soon since the government is now requiring all arriving passengers to undergo a two-week quarantine and medical surveillance. Government Chief Information Officer Victor Lam said the "app" won't threat people's privacy, it just "ensures" that they stay in one location during quarantine. The wristband pairs with the persons cell. Here's more here on how it works.
The Israeli Ministry of Health has released a new mobile app called "The Shield" that will alert users if they have been at a location in Israel at the same time as a known Coronavirus patient. This app, available for both Android and iOS, works by collecting the GPS and SSID (WiFi network) information of a user's mobile device throughout the day. This data is saved only on the mobile device and is NOT transmitted to the Ministry of Health, other government agencies, or any organization. Here's the analysis. It's in Hebrew...