NHS Test and Trace app updated to stop 'ghost' notifications - here's what you need to know

An update to the coronavirus app for England and Wales is being rolled out to straighten out accuracy issues and fix other gremlins.

The technology uses Bluetooth on smartphones to keep an anonymous log of other app users that an individual comes into contact with, informing them if they have been near someone who tests positive for the virus.

Since its launch on September 24, the app has been downloaded 19 million times by around 40 per cent of eligible smartphone owners, according to the Department for Health and Social Care (DHSC).

The latest set of improvements will better estimate distance between people to increase the accuracy of close contact notifications sent out by the app.

Using a combination of distance, proximity and infectiousness of a contact to calculate the risk threshold, the update should reduce the number of low risk contacts notified to self-isolate, without impacting the number of high-risk contacts being informed.

Worrying notifications which told users they had “possible Covid-19 exposure” will also no longer appear.

At the time, DHSC said these particular alerts were default privacy notifications from Apple and Google – who created the underlying technology – to alert people that the app is sharing information with the system.

“The team behind the app are continually working to improve its accuracy and user experience, to make it as simple as possible to keep users and their loved ones safe,” said Gaby Appleton, NHS Test and Trace director of product.

“We are thrilled that over 19 million people have chosen to download the app to help protect their loved ones while preserving their privacy, and that over 680,000 QR codes have been created by businesses to support digital contact tracing.

“This update builds on that success by increasing accuracy, and also removing ‘ghost’ exposure notifications, meaning users will only be notified if they need to self-isolate.

“The more people who use the app, the better it works, so I encourage all those who have not yet downloaded the app to do so.”

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In these confusing and worrying times, local journalism is more vital than ever. Thanks to everyone who helps us ask the questions that matter by taking out a digital subscription or buying a paper. We stand together. Nancy Fielder, editor.