NHS Covid-19 app: how does track and trace work?

After months of delays and millions of pounds, the NHS belatedly launched its official contact tracing in England and Wales on the 24 September.

The so-called NHS Covid-19 app asks users who have been near someone with a positive coronavirus test result to self-isolate for two weeks.

It also allows users to check-in to pubs, restaurants or other venues by scanning a QR code on their phone. They will then get an alert telling them to self-isolated if other visitors at the same time are found to have been infected. 

Matt Hancock, the health secretary, revealed that the app had been downloaded on to 12.4 million devices by noon on Monday, despite early teething problems, hailing it as "the fastest download of an app in British history".

For many, however, confusion persists about how exactly the app works. Here's everything you need to know about how to get set up and use the NHS Covid-19 app:

How do I download the NHS Covid-19 app?

To download the app, visit the App Store on your iPhone, or the Google Play Store on your Android phone. The app is only available on smartphones, and cannot be used on a smartwatche or tablet.

Open the search screen and type “NHS Covid-19”. Then download the app on your phone.

The app will only work with recent smartphone operating software. So you will need to have iOS 13.5 or later installed on your iPhone or Android 6.0 or later  on an Android phone.

To update the operating system on your iPhone plug your device into power and connect to the internet using Wi-Fi. Then go to Settings, General. Then tap Software Update.

To update on an Android phone, first make sure your device is connected to Wi-Fi. Open Settings, then select About Phone. You can then select Check for Updates. If an update is available, an Update button will appear, allowing you to install the latest system.

Some older devices, such as the iPhone 6 and older iPhones, won’t be able to run the app. Some of the latest Huawei handsets will also be unable to use the app.

How do I activate the app?

Once you have downloaded the app, you will be presented with a Privacy Notice. Read through it to know how your data will be used, and click Agree if you wish to continue using the app. 

You will then be asked to enter the first part of your postcode, as shown in the image below. At this stage an alert should appear asking you to enable Covid-19 exposure logging and notifications. This will allow the app to notify you if you have been exposed to someone with the virus.

Another alert will then pop up asking if the app can send notifications to your phone. Once you have enabled this, the app should be ready to use. 

 

How does the app work?

The app is powered by an Apple and Google-developed system, using Bluetooth to keep an anonymous log of close contacts who have come within two metres of a person for 15 minutes or longer. 

If two people who are using the app are in close contact to one another for more than five minutes, they will exchange keys, or Bluetooth "digital handshakes". The Bluetooth signal strength is used to measure proximity.

The data logged through these interactions is used to build up a points score of how many times and how long someone has interacted with another person over the course of a day. 

If someone tests positive for coronavirus, they can tell the app, which will then ping their keys to a central server and in turn find out who has been in contact with that individual.

Should the system determine a person as a close contact, they will be automatically sent a notification asking them to self-isolate for two weeks. The recipient of the alert is not told who triggered the notification.

Anyone who receives an alert, even if they don't have symptoms or later receive a negative test result, must self-isolate for 14 days.

What other features are available?

A QR code scanning feature is available, allowing people to check in to venues they visit and share their contact details for human tracing efforts.

Some 160,000 businesses have already downloaded QR codes for use in their facilities.

The app also has a function that enables users to book a test,  a local risk-level alert tool, a symptoms-reporter tool and a countdown timer to keep track of how long to stay in self-isolation.

The app is  available to people aged 16 and upwards, and currently available in eight languages.

Will the app drain my battery?

Because the app requires Bluetooth running in the background to scan for potential exposures to people with the virus, there have been concerns that the app may drain smartphone batteries.

But the app is likely to only drain 5pc or less of your battery life, meaning you shouldn’t see a dramatic reduction in how long you can use your phone for.

How will the NHS Covid-19 app use QR codes?

You’ll start to see official NHS posters featuring a QR code in venues across the UK. These codes can be scanned using the NHS app to let it know where you were and at what time, helping to track who may have come in contact with someone with a positive diagnosis.

It does this by adding the venue to the app's "digital diary". In England, the user will not need to give their personal details to the venue.

To scan a venue’s QR code, open the NHS app and tap the “Venue check-in” button on the main menu once the app is  functioning.

Point the app’s camera screen at the QR code and wait for confirmation that it has been scanned successfully.

You don’t need to do anything else - this means the app has registered where you are.

If other people were at the same venue at the same time as you, and later test positive for coronavirus, you will receive an alert.

What does my postcode district risk level mean?

You provide the first half of your postcode to the app so the government can notify you when the risk level in your area changes. Here's what each risk level means:

High

High risk means your local authority is using additional measures, such as lockdown, to reduce transmission.

Medium

If your area is at medium risk then your local authority, or a neighbouring local authority, has higher levels of infection than in other parts of the country. A local area plan may have been put in place to reduce infection, such as additional testing in care homes or added mobile testing capacity.

Low

Normal coronavirus control measures are in place.

How will the app help me book a test?

You can report details of your symptoms on the app. If they suggest possible Covid-19 infection, the app will ask you to book a test for yourself and everyone in your household online. You will also have to self-isolate for 14 days.

If you booked a test a different way, you can still link your test result to the app if you received a positive result.

To link your test result to the app, select Enter test result on the home screen of your app. Then, enter the code you received from the testing service by email or text.

What happened to the previous NHS app?

Based on Apple and Google’s privacy-centric software, the app marks the second attempt by the Department of Health and Social Care (DHSC) to develop a software to bolster the contact tracing effort.

A first version that stored some information centrally was ditched after an unsuccessful trial on the Isle of Wight in May.

The app had been sent back to the drawing board after the Government decided its approach presented too many technical challenges. 

Technical problems included an audit that found it could detect only one in 25 contacts on Apple phones in some cases. The app also did not work on Android phones that were more than four years old.

The root of these problems were due to the fact the NHSX app was trying to work around privacy limitations placed on smartphones by Apple, which makes iPhones, and Google, which makes Android.

These limitations meant that when iPhones went idle, they would stop registering Bluetooth matches, making the technology ineffective. 

Should I be worried about my privacy?

Some people have flagged concerns about patient privacy. Dr Yves-Alexandre de Montjoye, head of the Computational Privacy Group at Imperial College London, has warned that such apps could “collect sensitive information like location data”. 

“We need to do everything we can to help slow the outbreak. Contact tracing requires handling very sensitive data at scale, and solid and proven techniques exist to help us do it while protecting our fundamental right to privacy. We cannot afford to not use them,” he said. 

Mr Hancock has pushed back against the privacy concerns, claiming that data would only be held as long as it was needed and that “all data will be handled according to the highest ethical and security standards”.

“If you become unwell you can securely tell this new NHS app, and the app will then send an alert anonymously to other app users who you’ve been in significant contact with,” the health secretary said. 

What if I live in Scotland or Northern Ireland?

Scotland and Wales have separate contact tracing apps which you can download and use. The NHS app for England will not work in these countries, so you’ll need to download different apps and switch over if you already have England’s app.

For people in Scotland, go to your app store and search for “Protect Scotland.”

For people in Northern Ireland, go to your app store and search for “StopCOVID NI.”

Both apps work in the same way as England’s app, meaning you need to set them up first and turn on Bluetooth so that they can continue running in the background.

If you already have a different country’s app installed, you can switch your contact tracing region over by opening the new app. Tap “Allow” when asked if you want to switch to the current app for exposure notifications.

What other issues have there been so far with the app?

Unable to share positive test results

Officials were forced to urgently remove a major blindspot in the Government's Covid-19 app just days after it launched which meant that more than a third of daily tests were being excluded from the system.

It emerged that those who tested positive for the virus in NHS hospitals and Public Health England (PHE) labs were unable to share their result using the official contact-tracing app for the first 48 hours after its introduction on Thursday.

Tests carried out by the NHS and PHE make up one in three of those carried out each day, and their exclusion would have meant that casual contacts of a large proportion of medics who tested positive for the virus would not have received automatic notifications asking them to isolate.

The Department of Health has  now fixed the issue.

Possible exposure notifications

Some users of the app have reported they have received notifications which read "Possible Covid-19 exposure. Verifying exposure info. The app has accessed the date, duration and signal strength of this exposure.”

However, no information is provided about whether the user should self-isolate. 

The government claims these notifications from the NHS app are "default messages" and do not require a person to self-isolate for the required period. However, confusion around the messages has already led to some people needlessly isolating for 14 days. 

"I'm now self-isolating, just to be on the safe side... I don't know whether it's correct or not," Maurice Leaver told Sky News. 

The alert is a default message sent by Apple and Google when it detects that your phone has been close to a user who has tested positive for coronavirus. However, the system still needs to check how long and how close you were to that person before it asks you to self-isolate.