The system records contact as when a smartphone is within a couple of feet of another device for up to 10 minutes. Bluetooth wireless technology can sense devices from up to 15 ft away.
Even if people from different countries or states have different contact tracing apps, the system is interoperable and will be able to alert them to exposure. Authorities that want to collect location data of people will not be allowed to use the technology, but are open to building their own.
In coming months, they will integrate the technology directly into their operating systems to reach more people. Their tools will be “decentralised” and not send data to central health authorities, but will instead pass it from phone to phone.
Google said that the tools would be added to Android via a download in the Google Play store. Apple will offer it via an iOS software update. Apple said the goal is to make it compatible with as many iPhones as possible, including older models.
The functionality will only be available to public health apps so outsider developers won’t be able to use that data. It also means that users will have to download an official app to input test results.
When will it launch?
Mr Hancock had said the NHSX app would be launched as soon as mid May but on June 17 a government health minister said that contact-tracing app will not be ready until winter and “isn’t the priority at the moment”.
Lord Bethell, the Junior Health Minister, told MPs of the Science and Technology Select Committee the contact-tracing app was not the focus of Test and Trace’s efforts.
When asked for an exact date, he added he was “managing expectations” by saying winter, although said the government had not scrapped the app and still planned to launch it.
He told MPs: “We are seeking to get something going for the winter, but it isn’t the priority at the moment.”