Coronavirus: UK ditches contact-tracing app to move to Google-Apple model

The move marks a huge U-turn from the government, which has asserted for months that it would not be changing the app’s model.

The UK is abandoning its existing contact-tracing app and switching to the technology provided by Google and Apple.

The government confirmed the major U-turn on Thursday, after having insisted its own centralised model was more effective than that proposed by the technology companies.

Baroness Dido Harding, who is heading the government’s test and trace programme, and Matthew Gould, the chief executive of NHSX, said the decision was made after “rigorous field testing”.

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This testing showed that the NHS app identified 75% of contacts made on smartphones running the Android operating system, but only 4% of those on iOS – compared to 99% when using the Google and Apple framework.

Google and Apple collaborated to allow mobile devices to use Bluetooth in the background and register when they come within close proximity of another mobile phone.

But the collaboration required health authorities’ apps to utilise a decentralised model of data storage – keeping the list of contacts on each device, rather than uploading it to a central authority – which they said would protect users’ privacy.

As the iOS and Android mobile operating systems are run on 99% of the world’s smartphones, the companies’ technical designs have a fundamental say in how contact-tracing apps work.

Despite this the government asserted that by holding the data on contacts in a centralised manner they would have been able to develop valuable epidemiological data about how the virus is spreading.

The centralised model would also have helped prevent against people causing mischief with the system by giving the authorities an edge in detecting false positives.

However, issues remain with the way that the Google and Apple model uses Bluetooth to detect proximity, with some devices confusing phones in pockets one metre away with a phone in a hand three metres away.

The NHS app had managed to improve on this, according to Baroness Harding and Mr Gould, who said their innovation would be shared with the technology companies.

They said: “As part of a collaborative approach we have agreed to share our own innovative work on estimating distance between app users with Google and Apple, work that we hope will benefit others, while using their solution to address some of the specific technical challenges identified through our rigorous testing.”

Despite being initially promised for mid-May, a health minister has now said that the NHS app will not be ready before winter.

Lord Bethell confirmed the government still planned to introduce the contact-tracing app, describing it as “a really important option for the future”.

The app has been the subject of a trial on the Isle of Wight, where the Department of Health says it has been downloaded by 54,000 people.

Lord Bethell said the trial had been a success, but admitted that one of its principal lessons had been that greater emphasis needed to be placed on manual contact tracing.

“It was a reminder that you can’t take a totally technical answer to the problem,” he said.

Problems with manual contact tracing have been apparent in NHS statistics which today revealed that at least a quarter of people who test positive for COVID-19 in the UK are being missed.

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