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Why downloading the NHS Covid-19 app helps in the fight against coronavirus

Dr Sarah Jarvis and Dr David Bonsall on the importance of continuing to use the app

Monday 19 October 2020 17:11

By downloading the NHS Covid-19 app, smartphone users in England and Wales are able to play a key part in helping to protect others against the spread of coronavirus, safe in the knowledge that their privacy remains protected. 

Using Bluetooth technology, app users can be anonymously notified if they have come in to contact with someone who has tested positive for coronavirus or visited a venue which has recorded an outbreak – alongside receiving updates about the risk level in the local area. 

The technology, developed by Apple and Google, doesn’t use GPS and instead employs exposure logging through a daily-changing code associated with each device that has the app. 

No third party is able to associate the code collected from your device to you or your phone, so you don’t have to worry about privacy issues.  

App users are anonymous and the app cannot be used to track your location, for law enforcement, or to monitor self-isolation and social distancing.

Here, GP Dr Sarah Jarvis, NHS Test and Trace spokesperson, and Dr David Bonsall, researcher at Nuffield Department of Medicine, University of Oxford and clinician at John Radcliffe Hospital, explain the importance of downloading the app…

Dr Sarah Jarvis

Dr Sarah Jarvis

What are the features of the NHS app?

I was highly critical of the previous app, but all my questions and concerns have been addressed. That’s why I agreed to be a NHS Test and Trace spokesperson.

The app alerts you if you have been in close contact with somebody who has tested positive for coronavirus, but it is only people who have been in close contact with someone for 15 minutes or more.

The app allows you to alert other users you’ve come into close contact with, anonymously, if you test positive. There is a built in QR scanner to check in to places quickly and easily – which designated venues in certain sectors now have a legal requirement to display a QR code.

Why would you recommend everyone to download the app and how will it make a difference?

Downloading the app is part of the solution. Every country which has done well with Covid-19 has got one of these apps. Singapore has had one for nine months.

If only a small proportion of the population take this up, it is going to increase the numbers of people being alerted and increase the number of people who are told they could be at risk of spreading the virus. That means that we can get the R number – infection rate – down and hopefully prevent a general lockdown.

Does the app protect your privacy?

They worked with Google and Apple to develop the app. Any data shared with the app is only held on your phone, so if you decide to delete the app – which you can do at any time – all the data is deleted as well. If you test positive and you give permission for details of your contact, they are only random numbers. No personal information will be sent to every app in the country. The app will recognise if one of those numbers matches one of the numbers in their phone.

Dr David Bonsall

Dr David Bonsall

Why is a contact tracing app important?

We discovered that the virus was being transmitted from a significant number of people who didn’t know they were infected. You have left behind enough virus to sustain the spread. The tool that you use to identify people who don’t know they’re infected is contact tracing.

What research is there to suggest that this will work?

We know it takes about five days to develop symptoms, and that the time it takes to transmit to someone else is around five days. At that five-day point, you’re just as likely to infect someone in the future as you are to have in the past.  

The minimum number of people you need to have an effect is two. If you download it and I download it, and we come into close contact, if you get infected and the app notifies me that I might be infected, I don’t go and visit my gran as a result. I can help protect her. Gran doesn’t need the app to benefit from it.

How does the app work?

This system doesn’t track you; it doesn’t use GPS. Your phone generates random codes and it listens to other phones and communicates with them. You have, on your phone, codes that are signatures of phones you’ve come close to. You have to be close for a prolonged period to get those. 

Then, if you or someone you’ve been close to develops symptoms, requests a test, and the result is positive, you submit your personal codes to NHS Test and Trace. Everybody else’s phones are constantly looking at those codes to see ‘yes, I’ve seen that code – it comes from somebody who’s tested positive.

Visit the App Store or Google Play and download the NHS Covid-19 app now and learn more at