The government is abandoning efforts to develop its own coronavirus contact-tracing app in order to focus on technology from Apple and Google.
In a major U-turn on Thursday, the app developed by the NHS’s digital arm will now be dropped, but some features will be incorporated into a new design with the technology giants.
Health Secretary Matt Hancock defended the decision, saying testing on the Isle of Wight had uncovered a “technical barrier”.
He told the daily coronavirus briefing: “We have agreed to join forces with Google and Apple to bring the best bits of both systems together.
“We found that our app works well on Android devices but Apple software prevents iPhones being used effectively for contact tracing unless you are using Apple’s own technology.”
Mr Hancock said that the NHSX app was better at measuring distance than the Google/Apple model.
“As it stands, our app won’t work because Apple won’t change their system, but it can measure distance,” he added.
“And their app can’t measure distance well enough to a standard that we are satisfied with.”
Mr Hancock could not say when the contact-tracing app would be ready for roll-out, having previously said it would be available in mid-May.
“We’re working on it,” he told the Downing Street briefing.
“We’re not going to put a date on it I’m afraid because I’m absolutely determined that, whilst this technology can help, it’s got to be working effectively.”
Baroness Dido Harding, who is heading the government’s test and trace programme, said neither app in their current forms were reliable enough.
“This is a global challenge,” she said.
“What we have done in really rigorously testing both our own COVID-19 app and the Google/Apple version is demonstrating that none of them are working sufficiently well enough to actually be reliable to determine whether any of us should self-isolate for two weeks.
“That’s true across the world.”
Labour said the U-turn was “yet another example” of the government’s response to the crisis being “slow and badly managed”.
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 with 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 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 Matthew Gould, the chief executive of NHSX, 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.”
Health minister Lord Bethell said that the NHS app would not be ready before winter.
He 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 on Thursday revealed that at least a quarter of people who test positive for COVID-19 in the UK are being missed.
Analysis by Tom Rayner, political correspondent
It was made more uncomfortable still by the fact the health secretary was unable to provide a time frame for when a new version might be available, despite it initially being hailed as one of the key components of the test and trace process that would enable lockdown to be eased in lieu of a vaccine.
Labour’s shadow health secretary Jon Ashworth suggested it was part of a catalogue of examples where the government has overpromised without listening to warnings, and then been slow to manage the fall-out.
But at the Downing Street press conference the Health Secretary Matt Hancock was at pains to point out that this was neither a u-turn, nor an abandonment of the pursuit of a contact tracing app – instead, he suggested testing had shown that both the NHSX app and the alternative platform on offer from Google and Apple had flaws.
Mr Hancock claimed that because the government had, in effect, ‘backed both horses’, the UK was in a position to pull together the best aspects of both systems, and jettison the bits that didn’t work – in the NHS app, that was identifying contacts, in the google/apple platform, the identification of distance.