iOS 13.7 includes built-in COVID-19 notification system — Apple World Today

The exposure notification system uses Bluetooth signals from smartphones that have opted-in to determine how closely and for how long two phones were nearby, without collecting the location or identify of the users. The ability to opt-in to the system without downloading an app is intended to improve adoption of the system, which would improve its effectivity, as it requires a large number of people sharing Bluetooth signals to work.