One in 13 Britons using the NHS Covid-19 app have been sent an alert telling them they have been exposed to the virus and must self-isolate.
Department of Health bosses revealed today the application had pushed alerts to 1.7million of its users since it launched in September.
A total of 21.6million people in England and Wales have signed up to the service, the equivalent of 60 per cent of the adult population. But No10 has refused to say how many are active users.
Analysis by Oxford University also published today found the app had prevented almost 600,000 cases.
Health Secretary Matt Hancock praised the app as an ‘important tool’ and said it was ‘hugely effective at breaking chains of transmission’.
Mr Hancock himself was forced to self-isolate last month after being pinged by the application for a potential exposure to the disease.
The £35million project, which was plagued by glitches and bugs early on in its rollout, has repeatedly been described as a ‘waste of money’ by Labour.
The app’s launch was pushed back for months after it failed to pass trials on the Isle of Wight. Early versions showed the app drained battery power quickly, sent people phantom alerts and couldn’t be downloaded on some types of smartphones.
But, after ironing out its early issues, the app seems to be finally chipping away at the UK’s epidemic. Scientists today said the results were encouraging, but claimed ‘impact could be increased by more people using it’.
One in 13 Britons using the NHS Covid-19 app have been sent an alert telling them they have been exposed to the virus
The NHS Test and Trace app has sent 1.7million alerts telling Britons to self-isolate since it was first launched
The technology is designed to keep an anonymous log of individuals that people come into close contact with using Bluetooth, as well as allowing users to check into venues by scanning a QR code when restaurants and other indoor public spaces are open.
England and Wales’s app has now been downloaded 21.63 million times, which the Government says equates to 56 per cent of the 16-plus population.
HOW DOES ENGLAND’S CONTACT TRACING APP WORK?
Bluetooth technology keeps a record of which phones spend 15 minutes within 2metres (6’7′) of one another and then alert people if they have been near someone who later tests positive for Covid-19.
People’s phones are only recognised by the system if they are running the app themselves – it cannot detect others.
The contacts it keeps track of are all anonymous and phones exchange digital ‘tokens’ with every app-using phone within Bluetooth range.
If one person develops symptoms of the coronavirus or tests positive, they will be able to enter this information into the app.
The phone will then send out a notification to all the devices they have exchanged tokens with during the infection window, to make people aware they may have been exposed to COVID-19.
Each phone keeps an individual log of the Bluetooth profiles someone has come close to. These will then be linked anonymously to people’s NHS apps and alerts can be pushed through that even after the person is out of bluetooth range.
People can delete their data from this app at any time.
Users will also have an ‘isolation companion’ which has countdown timer if someone has to self-isolate, and will be able to ‘check in’ to places such as pubs and restaurants using QR codes.
They will also be shown what the risk level is in their local area based on the first half of their postcode, with places being categorised as low, medium or high risk.
How well does it work?
The app is far from perfect, with the Department of Health has admitted that around half of people who are warned they have been near an infected person will actually not have been within the 2m for 15 minutes danger window.
And three out of 10 people who were put at risk – 31 per cent – won’t receive a notification at all. In trials it had a 69 per cent accuracy rate at detecting people who had been at risk, and it was 55 per cent accurate at detecting people who had not.
Scotland and Northern Ireland have their own apps, though the same underlying technology means isolation alerts can be shared between different apps.
But the technology is automated and does not share details of those told to isolate with Test and Trace, as such the number of people who actually obey warnings from the app is unknown.
Research by The Alan Turing Institute and Oxford University – which is still subject to peer review – suggests that the NHS Covid-19 app has so far prevented 600,000 cases.
‘The impact of the app could be increased by more people using it: for each increase in users of 1 per cent of the population, the number of cases can be driven down by approximately 2.3 per cent,’ said Professor Christophe Fraser at the University of Oxford.
‘The epidemiological outlook remains concerning, and using the app can contribute to reducing infections until we are all vaccinated.’
People can book a test via the app and receive the result within it, or can enter the result manually if booked elsewhere.
Between the two, over 3.1million test results have gone through the app, 825,388 of which came back positive.
Meanwhile, a total of 253 venues were identified as ‘at risk’ due to outbreaks since December 10, triggering ‘warn and inform’ alerts being pinged to users who had checked into those places using posters with a QR code.
The Government said the venue check-in feature has been used some 103 million times.
Mr Hancock said: ‘The NHS Covid-19 app is an important tool in our pandemic response.
‘We know it has instructed hundreds of thousands of at-risk people to self-isolate since it launched in September – including me – and this analysis shows it has been hugely effective at breaking chains of transmission, preventing an estimated 600,000 cases.
‘Isolating and knowing when you have been at risk of catching coronavirus is essential to stopping the spread of this virus, and the app is the quickest way to notify you if you are at risk.
‘I want to thank all those who have played their part by downloading and using the app, and urge those who haven’t to take the simple step to protect your communities and loved ones and download it.’
Baroness Dido Harding, who heads up Test and Trace, said for every one per cent of Britons who download the app it is estimated it could reduce the number of cases by 2.3 per cent.
‘If you have already downloaded the app; I would like to thank you for helping to keep your loved ones safe, and please check that you always have the latest version of the app downloaded, as we make ongoing improvements to the app to help keep people even safer,’ she said.
The app uses Bluetooth on smartphones to keep an anonymous log of other app users that an individual comes into contact with.
If any of them test positive, it then sends alert informing users whether they have been near someone who has tested positive for the virus and need to self-isolate.
Since launching in September, it has suffered from several bugs, including a ‘ghost notification’ issue where users were sent alerts saying the app had detected a ‘possible Covid-19 exposure’ but would then give no further instructions or details.
Another glitch saw users who had their phone set to a language other than the 12 initially supported by the app be presented by a blank screen when opening the app. Both issues were fixed last year.