Luca Lorenzelli -

No silver bullets and ‘bumps in the road’ likely but UK contact-tracing app development gathers pace

UK scientific experts address doubts on contact-tracing app’s effectiveness, particular regarding data privacy, but admit that its nature may have to evolve as the roll-out scales up

Leading experts in the UK’s epidemiology, IT and communications sectors have revealed more details of the country’s much-vaunted contact-tracing app, which is now undergoing its first scale trial on the Isle of Wight.

Developed by NHSX, the NHS’s digital healthcare innovation unit, the contract-tracing app works by using Bluetooth to automate the “laborious” process of contact tracing and has the goal of reducing transmission of the coronavirus by alerting people who may have been exposed, so they can take action to protect themselves.

Once installed, the app will start logging the distance between a user’s smartphone and other phones nearby that also have the app installed using Bluetooth Low Energy. The anonymous log of how close users are to others will be stored securely on the user’s phone.

If a user becomes unwell with symptoms of Covid-19, they can allow the app to inform the NHS which, subject to sophisticated risk analysis, will trigger an anonymous alert to other app users with whom the user came into significant contact over the previous few days.

Yet even before the app has begun its second phase of development, dissenting voices have cast doubt over whether the technology is appropriate for the job at hand, questioning whether its centralised nature will lead to privacy breaches and also whether it will be of any use at all though lack of user uptake.

At a briefing with eminent colleagues, John Newton, director of health improvement for Public Health England and national Covid-19 testing coordinator, set the scene of the app’s new phase as a key strategic element for the UK government’s testing and tracing framework as it weighs up whether to relax social distancing regulations.

While admitting there were still some bumps in the road, Newton said the app’s new phase was a crucial development in managing risk and that it would not collect more data than needed.

Jonathan Van-Tam, deputy chief medical officer for England and professor of health protection at the University of Nottingham, said all the indices were pointing to Covid-19 infections being in decline and the aim of the app was to help with the campaign to lower levels of the disease going forward.

Matthew Gould, chief executive of NHSX, accepted that there was uncertainty over how many people would actually use the app, and emphasised that it was no “silver bullet”.

He said app users will receive an randomised ID after they enter in only the first part of their postcode. If anyone thinks they have symptoms of Covid-19, they can check this with the app and indicate their infection status accordingly. They will then be able to indicate to fellow app users their relative proximity, based on the strength of the Bluetooth signal.

As regards privacy issues, Gould stressed that IDs would not be sent to the NHS and that information could be deleted from phones at any time.

He also emphasised that the app was part of a general solution, along with testing, and that it was a solution for all the UK population. However, he recognised its limitations in that not everyone has a smartphone – especially on the Isle of Wight – and said the government and NHSX did not want to exacerbate the digital divide.

Read more about contact-tracing apps

One of the key issues about the app, however, was the use of a centralised database, unlike the approach advocated by Google and Apple, which will be rolling out their own device-based approach this week, first with an API and then with other contact-tracing technology throughout May.

Gould said the NHSX app’s approach was that it could more easily optimise the algorithms it was using. “The model that we’ve taken allows us to see the whole population [usage and] so we can make sure that the risk model we’re using is as accurate as possible,” he said.

“There are a range of reasons why we’ve gone for the model we have, but it’s also worth saying another thing, which is there’s been a lot of talk about us and Apple and Google taking different approaches, but I did just want to say this: firstly, we’re working very closely with Apple and Google – this is not a competition. There is a huge amount of cooperation going on.

“Secondly, we are all trying to achieve the same thing. And it’s natural for a new technology, that we are testing different approaches and seeing what works. And then the third point is really the most important, which is that our understanding of how the virus works and how the technology works, is developing. And, as it develops, if we think there is a better way of doing what we need to do, we won’t hesitate to change. We are interested only in one thing, which is what works best for the people in this country.”

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