The United Kingdom government has today launched its NHS COVID-19 app in the App Store, which supports the privacy-preserving Apple/Google Exposure Notifications API and aids the national contact tracing effort.
iPhone users can go to the App Store now and download the app for free; your device must be running iOS 13.5 or later. A counterpart app will also be available on the Google Play Store for Android devices.
After originally investing in a centralised server model back in April, the UK government bowed to public pressure and committed to change course and develop an app based on the Apple and Google framework.
The system Exposure Notifications API allows regional health apps to send out alerts to users if they have been in proximity to someone who has reported positive for COVID-19. The Apple and Google API was designed to be privacy preserving and power efficient. After agreeing to the permission dialog in the app, your device will passively collect hashed anonymous identifiers from nearby iPhone and Android devices who are also signed up with the NHS app.
If someone is reported as COVID-19 positive, their anonymous identifier is published on a server. This allows your device to check its local set of identifiers to see if there is a match. If a match is found, you will be presented with a COVID-19 Exposure Notification alert. (Note that this system works without sharing any user-identifiable information or your precise location.)
You can manage your Exposure Notification preferences in Settings. Simply navigate to the Exposure Notifications pane in the Settings app.
The NHS COVID-19 app also includes a QR code scanner, which British citizens are expected to use whenever they visit public places like restaurants, in order to record when they visited a venue. The government will use the information they collect from the QR code scanning to assist with human contract efforts.