Intended for healthcare professionals


Covid-19: App to track close contacts is launched in England and Wales

BMJ 2020; 370 doi: (Published 25 September 2020) Cite this as: BMJ 2020;370:m3751

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  1. Adrian O’Dowd
  1. London

The government is urging all adults in England and Wales to download the NHS covid-19 smartphone app as an additional way of tackling the spread of the virus.

However, experts have questioned how useful it will be, given that the overall test and trace system is still struggling to meet the demand and to provide quick results.

Latest official data show that in the week up to 16 September the results of just 28% of swab tests were received within 24 hours, down from a third the week before.1 Only 77.7% of the close contacts of people transferred to NHS Track and Trace were reached (83.8% the previous week), and of these 74.7% were asked to self-isolate.

The app for England and Wales uses a smartphone’s Bluetooth technology to log the amount of time a person spends near other app users, records the distance between them, and alerts users when they have been close to people who later test positive for covid-19. The app will trigger advice to self-isolate if users have been in close contact with a confirmed case and also enables them to check symptoms, book a test if needed, and get their results (box 1).

Box 1

Covid apps in the UK

England and Wales

The NHS covid-19 app has opted for a “Swiss army knife” approach with several features, including:

  • Alerts to let users know the level of coronavirus risk in their postcode district

  • QR check-in to enable users to check in at a venue and alert them if they could have been exposed to covid-19 there

  • Symptom checker

  • Ability to book a free test and get results

  • Timer feature to count down their period of self-isolation, with advice


The Scottish app does one thing: covid-19 proximity warnings. It sends the user warnings saying they might have been (for 15 minutes) within 2 m of somebody and should get checked out or self-isolate. Since it launched on 10 September the Scottish app is estimated to have been downloaded around a million times, which given that about 70% of the population has a smartphone means around a quarter of the potential population have it.

Northern Ireland

Similar to Scotland’s, this app tells the user if they been near someone who tests positive for covid-19. It also tells others if the user has tested positive. If a user receives an alert, the app runs a probability check to determine whether they need to self-isolate and provides advice.

Unlike the rest of the UK, where the apps are open to everyone aged 16 or older, this app is open to those aged 18 or above, although the Northern Ireland Executive has said this may change. More than 300 000 people have downloaded the app since it launched in July.


The launch of the app brings England and Wales into line with Scotland and Northern Ireland, which already have similar apps operating.

The government said that the app protected the user’s privacy, generating a random ID for an individual’s device and not holding personal information such as name, address, or date of birth. No personal data are shared with the government or the NHS.

The NHS Test and Trace team behind the app has worked closely with giant tech companies, including Google and Apple, after what were described as “successful” trials on the Isle of Wight and in east London that helped fine tune the new version.

The government has been criticised by health experts such as the charity the Health Foundation for so far failing to publish the results of pilots,2 although a spokesperson for the Department of Health and Social Services for England told The BMJ that during the trial 350 000 people downloaded the app and 67 495 activated it with unique codes. The government said it would publish a full evaluation of the trial in due course.

England’s health and social care secretary, Matt Hancock, said, “We are at a tipping point in our efforts to control the spread of this virus. With infection rates rising we must use every tool at our disposal to prevent transmission, including the latest technology.

“We have worked extensively with tech companies, international partners, and privacy and medical experts—and learnt from the trials—to develop an app that is secure and simple to use and will help keep our country safe.”

Simon Thompson, managing director of the NHS covid-19 app, said. “This new version is so much more than just a contact tracing app. It has a range of features that will quickly alert you if you’re at risk of coronavirus [infection]. The more people who use it, the better it works.”

The BMA said the app should allow more cases to be identified but that it needed to complement a properly functioning test and trace system.

Lilian Edwards, professor of law, innovation, and society at Newcastle University and an expert on internet law and artificial intelligence, told The BMJ, “The usefulness of the app is completely tied to getting testing and return on tests fixed. Unless you can get testing and return on testing down to about three days, then the app isn’t going to do anything useful. It’s not a magic bullet.

“A drawback to the app is whether enough people download it to get coverage. Originally they were saying it wouldn’t really do anything unless you had something like 70% or 80% of the population downloading, but they seem to have changed their mind on that now and believe it can be useful however many people download it.”


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