When Declan Chan arrived in Hong Kong from Zurich on March 17 after six weeks overseas, city officials made him put on a plain-looking white wristband and download an app called StayHomeSafe before he exited the airport.
He was told to register on the app once he got home, which would start a 14-day countdown, and walk to all four corners of his apartment so it could capture the location and confines of his home.