why the NHS’s bespoke contact tracing system had to be switched

How the two systems work 

Both Apple and Google’s contact tracing system and the NHS’s app use smartphones’ bluetooth connections to log when people come into close proximity, potentially spreading the virus. The apps are then designed to send alerts out to users when someone they have had contact with tests positive for Covid-19 or reports symptoms.

The key difference between the apps is how they handle users’ personal data and information. In the tech giants’ ‘decentralised’ system all the users’ information is kept on the phone. 

In contrast, the NHS initially opted for a ‘centralised’ system model, which saw data sent back to a Government server where it could be analysed.

NHS bosses argued a key benefit of their centralised system was it would allow the health service to rapidly track where infection hotspots were breaking out. They also said over time it would make the app more accurate at measuring distance between contacts.

NHS App problems 

The NHS App swiftly ran into issues when its trial was launched on the Isle of Wight last month. Initially, residents complained the app was bombarding them with notifications and not working on Android handsets. Then the app struggled when developers tried to update the Covid-19 symptoms in line with NHS guidance, leading to a new version needing to be developed.

However, yesterday the Government revealed the fatal blow was dealt when field tests revealed the NHS app barely worked on Apple’s iPhones. 

The Telegraph understands the NHS app was only able to pick up 4 percent of contacts on iPhones, compared to around 75 percent for Android phones. 

Officials from NHSX, the health service’s digital arm, initially said they had developed a ‘workaround’ for the Apple bluetooth problem, which was known about as early as April.

But yesterday it emerged that Apple phones were still missing the bulk of contacts as the iPhone operating system kept pushing the NHS app into the background when it wasn’t open on a phone.

Issues with Apple and Google’s model 

Meanwhile, the switch over to the tech giants’ decentralised model is not without problems. Yesterday, Health Secretary Matt Hancock, said the Apple and Google app was not as accurate at measuring how far apart people are when their phones log contact. 

NHS tests found the app could not tell if another phone was one or three metres apart.

Mr Hancock described the ability to measure distance as ‘mission critical’ to any contact tracing app that was being used to decide if people should self-isolate for two weeks.

The cost so far?

Health bosses have declined to give a figure for how much has been spent on the now redundant NHS App. However, analysis carried out for The Telegraph by the public sector analysts Tussell showed contracts totalling £8.5 million have been awarded to companies to develop NHS contact tracing app software. The majority of these have gone to the US developers VMware Pivotal Labs and Swiss digital company Zühlke. 

When will the NHS app be ready?

Mr Hancock had originally said he wanted the NHS App to be rolled out to the rest of the country by ‘mid-May’. Yet, after this latest U-turn, ministers are not giving a date as to when the new version will launch. On Monday, health minister Lord Bethell, said the app may not arrive until winter. NHS sources also suggested that technology could launch merely as a ‘companion app’ to the human contact tracing system if technical issues could not be resolved. This would see it only directing symptomatic people to where they can get a test and providing NHS advice.

What other countries are doing?

Most other European countries are now using the Apple and Google model for their contact tracing apps, including Germany, Italy and Denmark, which all launched their apps this week. One of the central criticisms of the UK’s centralised model was that it would not work with other European countries’ versions, potentially making it harder for Britons to travel abroad. 

Meanwhile, Germany also ran into the same problems as the UK around Apple’s bluetooth system when it tried to initially build its own centralised app. But German officials decided to switch to the Apple and Google model back in April, and launched their app on Tuesday. It has now been downloaded more than six million times.

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