UK Government announces u-turn on contact tracing App

The UK government today announced a u-turn on its COVID-19 contact tracing App, shifting from a proprietary centralised system to a decentralised system built around Apple+Google’s Exposure Notification system.

The centralised version trialled on the Isle of Wight worked well at assessing the distance between two users, but was poor at recognising Apple's iPhones.

Specifically, the software registered about 75% of nearby Android handsets but only 4% of iPhones.

By contrast, the Apple-Google model logged 99% of both Android mobiles and iPhones.

The technical limitations of the App were investigated by NRB Tech in early May, concluding:

While it seems like the App will work most of the time, as identified here there are edge cases where it won’t. That’s a risk weighed up against the benefit of gaining more data by using a centralised system. However, the UK is an outlier here. It seems that most countries will use Apple and Google’s approach when it becomes available. Building a bespoke system which doesn’t work in some edge cases seems like a big risk, and one that the NHS may now be reconsidering.

It appears that the trial on the Isle of Wight confirmed these issues. While precious time has been lost pursuing the centralised system, lets hope now that an effective solution can be developed using the now-released Apple-Google solution.