How the long- awaited contact- tracing app, launched today, will work

A CONTACT- TRACING app for England and Wales is due to be launched today after months of delay, technical issues and concerns about privacy.

The latest NHS Covid- 19 app has been trialled on the Isle of

Wight and in the London borough of Newham since mid- August after an initial model was scrapped.

The app can be downloaded from Apple’s App Store on iOS or Google’s Play Store for Android devices by searching for ‘ NHS Covid- 19’.

Once downloaded the app will rely on Bluetooth from your smartphone to keep a log of others who are also using the app whenever they are in close proximity to you.

It is able to do this by measuring the strength of the Bluetooth signal, as well as timing how long you were near each other. To be considered a close contact, it generally means having been within two metres of someone for 15 minutes or more, such as on a bus journey.

The app generates random codes every 15 minutes that are passed between phones, which allows it to keep identities hidden.

Should a person present symptoms or come back with a positive test, the app will ask their permission to check your codes with other app users, distributing them via a central system.

If a code matches the log stored on a person’s phone, it means they could have contracted the virus and will therefore be advised to self isolate.

The app is voluntary and employers do not have the power to force employees to install it on their devices.