This week the UK government performed an abrupt u-turn on its contact-tracing technology to tackle coronavirus.
The app it was developing with NHSX, the health service’s research wing, is set to be replaced with an app built using technology developed by Apple and Google, the US technology giants.
But what is so different about Apple and Google’s system? And why does the government believe it is the only way to move forward after lengthy delays to Britain’s previous plans.
Here are five key questions about the decision.
Why has the government switched systems?
Contact-tracing apps work by using Bluetooth signals to perform a digital “handshake” between devices. If two phones with contact-tracing apps installed come into close proximity for a set period of time – say ten minutes, then they perform a match.
If one person is later found to have coronavirus, the app can anonymously warn other people they have been close to, even if they are strangers, that they are at risk of infection. They can be informed via a text message or email and advised to self-isolate.
The Government has been testing its own app on the Isle of Wight since May. This was built without special software designed by Apple and Google specifically for contact-tracing.
The Government did not want to use this system, which placed restrictions on how data can be gathered. UK officials were concerned the Apple-Google version would therefore not provide enough useful information for public health experts to monitor the spread of the virus.
They also thought that their own system would be better at measuring distance that the Apple/ Google model.
In the press briefing, health secretary Matt Hancock said: “As it stands, our app won’t work because Apple won’t change their system, but it [the NHS app] can measure distance and their app can’t measure distance well enough to a standard that we are satisfied with.”
NHS tests found the Apple-Google system could not tell if another phone was one or three metres apart.
However, the NHSX project quickly ran into a host of basic technical challenges.
To work, the contact tracing app needed to work smoothly with all smartphones. In other words, whatever phone or operating system you own had to be able to communicate effectively via Bluetooth with any other person’s phone.
But developers soon found that they did not. For example, iPhones that fell idle or which were locked would no longer be able to match to other iPhones. The app would also not work on older versions of Android, Google’s operating system used on most non-Apple devices.
The problem for the Government is the system Apple and Google were developing would store data in a different way to the UK’s planned app. It would store all data locally on phones. In theory, this is more private.
Matt Hancock blamed Apple for refusing to make changes to its iOS software that would have allowed the UK app to work. He said: “As it stands, our app won’t work because Apple won’t change their system.”
The Government awarded contracts worth more than £11 million to companies to help develop its contact tracing app before its U-turn to work with Apple and Google.
According to Government records published online so far, 11 contracts have been awarded to private firms aiding the app’s development totalling £11,297,811.
How does it work and is it more private?
Apple and Google’s system is based on a different “decentralised” model. It is not an app, per se, it is a software system that health authorities can build on.
Germany, Italy and Switzerland have all built and launched apps based on its technology.
The Apple/ Google system is different in the following ways:
It stores data on someone’s coronavirus symptoms locally, which does not leave the phone. With the NHS’s app, this data was collected and stored on a central database to allow researchers to monitor the pandemic
When someone reports they have coronavirus through the app, other people are told via a “peer-to-peer” warning system. This means the information is routed directly to the smartphones of matched users. It does not travel to a central database and cannot otherwise be monitored.
The app is based on positive test results. Users only report into the app once they have a positive test. The UK’s app would have relied on unverified symptoms.
This system, which stops a health authority from collecting masses of data on its population, is seen as more private by Apple and privacy advocates. They fear mission creep where governments might start to collect huge amounts of other health data unchecked.
Crucially, Apple and Google are tackling some of the key technical challenges encountered by NHSX to allow iPhones to still be able to collect data, even when they are left idle.
When did Apple and Google launch it, and why has it taken so long to switch?
The tech giants launched their software tool on May 20, giving governments access to detect when Android and iOS devices came in close contact with one another when official apps were installed.
Apple and Google’s application programming interface (API), which was released after five weeks’ of discussions with various states, operates on a centralised basis. The two tech giants argue its system is considerably more private than the alternative that has been pursued by the UK up until now.
NHSX pursued a centralised model that would have seen significantly more health data accrued on state-owned servers.
The Government had been pushing is different approach since mid-March, which culminated in a live trial.
But this proved a disappointment. The UK app demonstrated the ability to pick up around 75pc of Android devices but just 4pc of iPhones.
Mr Hancock says that Apple’s software has prevented the NHS app from being used effectively.
The Government’s chase for a centralised app is what has seen Britain now push its date for a new app all the way back to winter.
Is it being used in other countries?
Several European countries have been using Apple and Google’s API to build their contact tracing apps so far. When the tech giant released the kit back in May, they said 22 countries had requested and received access to it.
Switzerland was the first country to make use of the API for its app. Ireland, Finland, Portugal, Austria, Singapore, and Australia are all making use of it too. Italy, Estonia, and Latvia are also building their apps on the tech giant’s API.
Like the UK, Germany performed a U-turn on its approach to contact tracing and ditched its approach in favour of Apple and Google’s system. However, Germany made the decision to do so back in April.
Does it actually work?
What is not known and has been questioned by some experts is whether Apple and Google’s system will actually work any better.
Most contact-tracing apps rely on Bluetooth signal waves. But these signals are bound up by the fundamentals of physics, and can, say be made less strong by a phone being in a pocket or bag, as opposed to being on a table.
They can also be affected by metal. The Telegraph has reported that, in some cases, the Apple/ Google app’s Bluetooth signal was missing 95pc of readings in one test on a bus.
Doug Leith, a researcher at Trinity College, Dublin, said that accurate proximity tracking using Bluetooth was “hard or perhaps even impossible”.
These problems mean it is still not known how effective contact-tracing apps will be, even with the might of Google and Apple behind them.