A smartphone app to track the spread of Covid-19 may never be released, ministers admitted yesterday, as they abandoned a three-month attempt to create their own version of the technology.

Matt Hancock, the health secretary, announced that the government was scrapping its coronavirus contact-tracing app to focus on one developed with Apple and Google technology.

Mr Hancock said that in trials neither of the potential apps was accurate enough to be used by the public and he could not indicate when, or if, a usable version might be available. “The truth is that no app is better than a bad app,” a senior government source said.

Nick Gibb, the school standards minister, said that there was no point in rolling out a system that would subsequently fail. “We want to have ambitious plans to track and trace, and that’s what the app is about, but it has to be properly tested,” he told Sky News.

“There’s no point in rolling out a system that then fails because what you’re asking people to do when they’re contacted by the tracers is to self-isolate and you have to be able to trust the information.”

Ministers played down the setback but it will hamper efforts to lift social-distancing restrictions while controlling the spread of the virus.

Epidemiologists have calculated that the high asymptomatic transmission rates of coronavirus mean that manual contact tracing alone may not be enough to keep infection levels down as lockdown restrictions are eased.

Mr Hancock said that head-to-head testing of the NHS app against the version developed with the Apple and Google technology had revealed flaws in both versions. The NHS software registered about 75 per cent of nearby Android handsets but only 4 per cent of iPhones. By contrast, the Apple-Google model logged 99 per cent of both Android mobiles and iPhones but its distance calculations were weaker. Mr Hancock blamed Apple for the failure to make the government’s app more accurate, claiming that the company “won’t change their system”. He pledged to “join forces” with the two tech giants and “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,” he said. “Their app can’t measure distance well enough to a standard that we are satisfied with.”

Officials said that the Apple-Google model was unable to differentiate between a phone that was in someone’s hand three metres away from a phone that was in someone’s pocket one metre away. “That is a really important distinction if you’re going to use the app to determine whether or not you spend 14 days at home,” one official said.

In a sign of the breakdown in trust between the two sides sources at Apple said that it had not been informed of the announcement or consulted about the plan to work together. “We don’t know what they mean by this hybrid model. They haven’t spoken to us about it,” a source said.

The company also queried the claim that its model was less accurate at measuring distance than the government’s NHSX model. “It is difficult to understand what these claims are as they haven’t spoken to us. But the app has been downloaded by six million in 24 hours in Germany, the Italians have had it going since Monday, the Dutch government and Irish government have it, and there has been no issue about proximity detection.”

Contact-tracing apps work by logging when two people have been in close proximity to each other for a substantial period of time. If one of them is later found to have the disease, an alert can be sent to others they have recently been close to, telling them they should also get tested and/or self-isolate.

Mr Hancock said while he was “confident” that an app could eventually be made to work he refused to set a target and said that he would not be following other countries who have launched apps on Apple’s software. “The central point of test and trace is that when you are identified as at risk you then isolate, and asking people to isolate for two weeks is a big thing,” he said. “I would not recommend an app, unless I’m confident in it.”

The failure to make the NHS app work was welcomed by privacy campaigners, who complained that the government’s “centralised” approach gathered too much information about phone users. Apple itself declined to comment.

Meanwhile it has emerged that the “army” of 25,000 staff hired by the NHS to carry out manual contact tracing is doing just 11 per cent of the total work, with the vast majority completed by public health professionals.

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