> Switching exposure alerts

I sometimes travel to different states and the UK. Can I use local contact tracing apps when away, and how will they protect my privacy?

From version 13.7 onwards, iOS supports a wide range of contact tracing apps covering many US states, European and other countries, and nations within the UK, each which Apple calls Regions. It also offers exposure notification which can work without a local app.

Adding specific support for other regions depends on whether they have an official app. To see, in Settings tap Exposure Notifications > Active Region > Add Another Region. This takes you to a list of countries, within which are lists of states (USA) and devolved nations (UK). Pick one and iOS informs you if its app is available. If it is, it can take you to the App Store to install it.

When you travel, enable Exposure Notifications > Availability Alerts, and your iPhone notifies you when you’re in a region with a supported app. Switch Active Region accordingly, and the local app takes over exposure notifications.

Public health services in each region with its own app provide servers to support Apple’s notification system, but they don’t get any personal info. If someone you may have been exposed to tests positive for Covid-19, your phone recognizes that when told of their private token, and notifies you. It doesn’t reveal their identity, nor upload your personal info to the server, but gives you a warning to isolate.