NHSX has said it will publish the source code, security and privacy designs of the Covid-19 contact tracing app currently under development.

The digital policy unit within the Department for Health and Social Care has also highlighted the ability of users to control and delete the data it collects in an effort to allay the concerns of privacy activists over how the app could be used.

Chief executive Matthew Gould and chief data officer of NHS England Dr Geraint Lewis outlined the development of the app which is aimed at automating contact tracing and complementing other steps to reduce the spread of the virus.

“As part of our commitment to transparency, we will be publishing the key security and privacy designs alongside the source code so privacy experts can ‘look under the bonnet’ and help us ensure the security is absolutely world class,” they said.

After being installed on a user’s phone, the app will use Bluetooth to log the distance between it and any others nearby that also have it, with the data feeding into an anonymous log.

If a user becomes unwell with symptoms of Covid-19 they will be able to choose to allow the app to inform the NHS, which will then use automated risk analysis to send an anonymous alert to any other user who had significant contact with the person in the previous few days.

It will also provide advice on what to do for anyone having been in contact with someone who has shown symptoms. The exact advice will be fine tuned and revised by scientists and doctors.

Future additions

There are already plans for future releases of the app that will give users the choice of providing the NHS with extra information to help it identify hotspots and trends in the pandemic.

They will also be able to delete the app and all associated data whenever they want, said Gould and Lewis.

“We will be totally open and transparent about your choices in the app and what they mean,” they said. “If we make any changes to how the app works over time, we will explain in plain English why those changes were made and what they mean for you.”

They added that NHSX is working with Apple and Google on the development of their own tracing apps.

Image from NHSX, Open Government Licence v3.0