In a major turnaround, the UK abandoned the operation of its current coronavirus tracking application and switched to a model based on technology provided by Apple and Google.
The Apple-Google design has been promoted as being more privacy oriented.
However, this means that epidemiologists will have access to less data.
The government now plans to launch an app in the fall, but says the product cannot involve contact tracing at this point.
Instead, the software can be limited to allowing users to report their symptoms and order a test.
Baroness Dido Harding – who heads the larger test and trace program – will only give the green light to the effective deployment of Apple-Google technology if she decides that it has been adapted to its intended use, which doesn is not currently the case.
Germany, Italy and Denmark are among the other countries that have moved from a so-called “centralized” approach to a “decentralized” approach.
The NHS has tested the two systems against each other in the past month.
The centralized version tested on the Isle of Wight worked well to assess the distance between two users, but failed to recognize Apple iPhones.
Specifically, the software registered about 75% of nearby Android handsets, but only 4% of iPhones.
In contrast, the Apple-Google model registered iPhones but its distance calculations were weaker. In some cases, he could not tell the difference between a phone in the pocket of a user at 1 m (3.3 feet) and a phone in the hand of a user at 3 meters (9.8 feet) ).
The experiences in Ireland have pointed to a similar problem.
The move comes the day after the BBC revealed that a former Apple executive, Simon Thompson, was behind the project.
Contact finder apps are designed to help prevent a second wave of coronavirus.
They work by connecting when two people have been in close proximity to each other for a substantial period of time.
If one of the users is later diagnosed with the disease, an alert can be sent to other people with whom he has recently been close, telling them that they should also be tested and / or self-reported. isolate.
The previous “centralized” design in the UK performed contact matches on a remote server.
The Apple-Google model performs the process on the handsets themselves, making it more difficult for authorities or potential hackers to anonymize the records and use them for other purposes.
One of the advantages of the switch is that the NHS Covid-19 application will be able to overcome a limitation of iPhones and perform Bluetooth “handshakes” when the software is running in the background.
Another is that it should be easier to make the app compatible with counterparts from other countries, which are based on the same system – including the Republic of Ireland and Germany.
Earlier this week, the European Commission said that France – which had adopted a centralized application – would face challenges in this regard.
“This is a welcome initiative, if it is delayed in a cumbersome and unnecessary way,” said Dr Michael Veale of the DP3T group, who promotes the decentralized model.
“The Google-Apple system is in a way unique to the country: born of research in a large consortium of universities led by Switzerland and including the UCL in the United Kingdom.
“The UK has no end of options and no reasonable excuse for not releasing the app quickly now. “
He added that developers should be able to adapt the code already used by Germany and Switzerland if necessary.
The government previously announced plans to roll out the app across England.
But because health is a decentralized problem, Northern Ireland, Scotland and Wales have yet to commit to this initiative.
“We will continue to work with the UK government to collect the information we need on data integration, technical information and overall timelines before we make any decisions about whether or not to support its use,” said a Scottish government spokesperson told the BBC.