The UK’s official coronavirus tracing app will now be based on the underlying model developed by Apple and Google. This version is decentralised, as opposed to the UK’s first implementation of the app that was centralised.
The difference is that Apple and Google’s model processes potential contact matches on individual phones, whereas the centralised system the UK started with processed matches on a remote server. The new system makes it far more difficult for potential hackers to deanonymise sensitive personal data.
The BBC reported that the old system was particularly bad at measuring distance between users via Bluetooth, with a test in the Isle of Wight only registering 4% of nearby iPhones compared to 75% of Android phones. This is compared to Apple and Google’s model that registered 99% of both.
Government ministers had insisted on using a centralised version as it stores anonymised data on an NHS database, supposedly allowing for better tracing and data analysis. This version, for privacy reasons, was not supported by Apple and Google. It now seems the government has had to switch to the companies’ model as it is more accurate.
Health Secretary Matt Hancock suggested Apple’s restrictions on third-party apps’ use of Bluetooth was a cause of the low numbers. It seems to smack of blame-shifting.
The government still plans to launch the app in the autumn, and it might even be without contact tracing and limited to users reporting symptoms to order a test. Apple and Google’s system was first reported in April.
It means that in reality, the government has wasted time and money – three months and millions of pounds, potentially at least £4.8, according to the Guardian – on an app that it now will not release, despite repeated assurance of the validity of the technology.