Britain’s ‘world beating’ Covid-19 tracing app had one problem – it didn’t work

In the West Yorkshire town of Batley last Saturday, the Fox and Hounds pub opened its doors after nearly four months under lockdown. Two days later, it was closed again.

A customer who visited the pub on Saturday called on Monday to say they had tested positive for coronavirus. The same thing happened at the Lighthouse in Burnham-on-Sea and the Village Home in Gosport and all three have closed for a deep clean and staff testing.

"They are doing the right thing by their customers and their communities. This is NHS Test and Trace working precisely as intended," health secretary Matt Hancock told MPs on Tuesday.

But it is not exactly how the test and trace system was intended to work because the NHS was supposed to have its own contact tracing app in operation by now. Heralded in March and announced in April with a promise that it would be “world beating”, the app was due to be launched by the middle of May.

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While other countries adopted the system jointly developed by Google and Apple, the NHS was developing its own app based on different technology. But on June 18th, the government changed course, abandoning its own app and moving instead towards developing an enhanced version of the Google/Apple model.

Dido Harding, who heads Britain’s test and trace operation, refused to say this week when the app would be ready and ministers cannot confirm that it will be launched before winter.

“It’s not something that we think that anybody in the world has got working to a high enough standard yet to give us the confidence that if we just receive an electronic message telling us to isolate that we would trust it,” she told a House of Lords committee on Monday.

Centralised database

Covid Tracker Ireland and other contact tracing apps based on the Google/Apple technology use a decentralised approach, with data collected and held on devices and shared with other devices. Britain wanted a centralised approach that would see data collected by the app sent to a database for use by the NHS.

The British government hoped that a centralised database, which would also have access to location data, would help to identify local coronavirus outbreaks quickly. The app would require users to self-report symptoms and the central database would then identify people the app showed they had been in contact with.

The planned app faced immediate criticism about risks to privacy and data security but trials on the Isle of Wight showed it had a bigger problem: it didn’t work.

The app was good at calculating the distance between two devices but not so good at finding them. It found only 4 per cent of iPhones and missed 25 per cent of Android devices.

Britain is now trying to develop a hybrid model with some of the centralised features of the NHS system built on to the decentralised Google/Apple model. Simon Thompson, who is in charge of building the app for the NHS, said this week that it would be a "significant benefit" to Britain's effort to control coronavirus. But like Harding, he was unable to say when it will be launched.

“We really recognise that the introduction of the app is urgent and important, but it has to be a product that people can trust,” he said.

“We are leaving no stone unturned to make sure we can accelerate at pace and have a product that works that we can put in the hands of our citizens to make sure they have the maximum freedom and minimum risk.”