Why the NHS Test and Trace app is doomed to fail: Major review finds contact tracing via smartphones 'is unlikely to reduce the spread of Covid-19'

  • Researchers examined the findings of 15 different contact tracing app studies
  • They found that even with a high take-up they don't work alone to slow the virus 
  • The NHS Test and Trace app was launched as a pilot in the Isle of Wight last week 
  • The team say apps are not a valid replacement for human contact tracing 

The new NHS Test and Trace app won't work unless the vast majority of the country installs it and even then social distancing will still be required, a new study claims.

The NHS app launched in the Isle of Wight last week as a pilot scheme, with users urged to scan barcodes when they go out to create a 'virtual diary' of movements.

This is the second trial on the island by NHS following its disastrous first attempt, which was abandoned in June.    

A new study by University College London found that these types of tracking apps only work if the vast majority of a population install and actively use them. 

By reviewing 15 earlier scientific studies into the use of the apps, the team found that even if 80 per cent of a population install them other public health restrictions would still be needed to slow the spread of the deadly virus. 

These measures include restrictions already in use to slow the spread including social distancing, wearing masks indoors and even closing pubs.

Researchers say that 'automatic and semi-automated' contact tracing apps are no substitute for human contact tracers calling people to tell them to stay indoors. 

The NHS has used several mobile applications during the course of the pandemic to help patients assess and report their symptoms. This week, they have started trialling the 'NHS Covid-19' contact-tracing app, after a series of delays in the development process

The NHS has used several mobile applications during the course of the pandemic to help patients assess and report their symptoms. This week, they have started trialling the 'NHS Covid-19' contact-tracing app, after a series of delays in the development process

Researchers say that 'automatic and semi-automated' contact tracing apps are no substitute for human contact tracers calling people to tell them to stay indoors

Researchers say that 'automatic and semi-automated' contact tracing apps are no substitute for human contact tracers calling people to tell them to stay indoors 

NHS re-launches delayed contact tracing app using Google and Apple tech 

The much-delayed NHS Test and Trace smartphone app is being re-launched today with a second round of trials on the Isle of Wight and in the London borough of Newham.

England's beleaguered app, of which the first version had to be scrapped in June after a string of failures, has now been recreated using technology made by Google and Apple.

Officials are rolling out trials of the app - which was originally slated for release in mid-May - to some staff in the NHS and residents of the two areas to test whether it is good enough to use nationwide.

If it is found to work, it will be used alongside the human contact-tracing system which is based on call centres and local councils visiting people's homes.

Bluetooth technology will keep 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.

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.

The app will rely totally on members of the public co-operating, volunteering to let it track their connections and following the instructions it gives them on getting tested and self-isolating.

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The team from UCL say evidence on the effectiveness of automated contact tracing systems is limited and there is an 'urgent need for further evaluation of these apps'. 

The original NHS app was supposed to have been launched across the country in mid-May following its trial period. 

But it was scrapped in June as it had a number of flaws and the government announced a dramatic U-turn as it ditched its self-made version in favour of the API built by tech giants Apple and Google. 

A trial of a revamped app has now started in the Isle of Wight and Newham in east London but officials can't say if or when it will be rolled out more widely.

Even under optimistic assumptions - where up to 80 per cent of people are using a contract tracing app with 90 per cent of the identified contacts following quarantine advice - physically distancing and venue closures would still be required. 

Health Secretary Matt Hancock insists the app will 'help keep the country safe' but there are still concerns over high false positive rate - up to 45 per cent. 

Lead author Dr Isobel Braithwaite, of the UCL Institute of Health Informatics, said the studies painted a consistent picture that the automatic apps don't work alone.

'The systems will require large-scale uptake by the population and strict adherence to quarantine advice by contacts notified to have a significant impact on reducing transmission,' Dr Braithwaite explained.

'Although automated contact tracing shows some promise in helping reduce transmission of Covid-19 within communities, our research highlighted the urgent need for further evaluation of these apps within public health practice.' 

The researchers looked at more than 4,000 studies on automated and partially-automated contact tracing and found 15 relevant research papers. 

Dr Robert Aldridge, of UCL, said there isn't evidence about whether a notification from a smartphone would help break chains of transmission by giving advice to isolate due to contact with a case of Covid-19.

They say being given advice by a human public health contact tracer is more effective at encouraging people to stay indoors. 

The NHS Test and Trace app will tell people their local area risk level based on the first half of their postcode
People will be able to 'check in' o places they visit using QR codes.
If someone tells the app they have symptoms it will urge them to self-isolate and order a swab test

The NHS Test and Trace app will tell people their local area risk level (left), allow them to check in to places they visit (centre) and will warn people if they have been in contact with someone who tests positive or if they report symptoms themselves (right)

'We urgently need to study this evidence gap and examine how automated approaches can be integrated with existing contact tracing and disease control strategies, and generate evidence on whether these new digital approaches are cost-effective and equitable,' Dr Aldridge explained.

The researchers said that if implemented effectively, contact tracing apps may offer benefits such as reducing reliance on human contact tracers, but it could also increase the risk of Covid-19 among vulnerable groups and raises privacy concerns.

Dr Braithwaite said: 'We should be mindful that automated approaches raise potential privacy and ethics concerns, and also rely on high smartphone ownership, so they may be of very limited value in some countries.

'Too much reliance on automated contact tracing apps may also increase the risk of Covid-19 for vulnerable and digitally-excluded groups such as older people and people experiencing homelessness.'

The findings have been published in the medical journal the Lancet

The landmark study will come as a hammer blow to the government's hopes of creating a robust and effective track and trace system. 

Matt Hancock had initially promised the NHS would build its own app which would work alongside human contact tracers. 

It was based on a centralised model which funnelled all the data from handsets to a central server in NHS headquarters. 

This was in direct contradiction to the approach taken by Apple and Google, who teamed up in a rare partnership to create a framework which countries could use to build their own app. 

HOW IS APPLE AND GOOGLE'S TECHNOLOGY DIFFERENT TO THE FAILED NHS PROJECT? 

It is not clear why the NHS app was so much worse at using Bluetooth to detect other phones than the Apple/Google technology is.

Officials have not explained exactly why or how the new system is better at measuring the distance between two phones, but Apple and Google's own software appears to work significantly better when the phone's screen is locked.

The companies make the phone operating systems themselves so are better able to fit the Bluetooth software around that, whereas the NHS was unable to make a program that could prevent the app going into sleep mode. 

The main difference between the two apps is the way they store data.

Both keep a log of who someone has come into close contact with - but the NHS's app would have kept information in a centralised database, while the Google/Apple app is de-centralised. 

NHS app: Lists on NHS servers 

The NHSX app would create an alert every time two app users came within Bluetooth range of one another and log this in the user's phone.

Each person would essentially build up a list of everyone they have been in 'contact' with. This would be anonymised so the lists were actually just be numbers or codes, not lists of names or addresses. 

If someone was diagnosed with the coronavirus all the app users they got close to during the time that they were considered infectious would receive an alert telling them they have been put at risk of COVID-19 - but it wouldn't name the person who was diagnosed. 

NHSX insisted it would have deleted people's data when they get rid of the app, but not data uploaded to the NHS server if they or a contact tested positive.

Apple/Google: Contained on phones

In Apple and Google's de-centralised approach, meanwhile, the server and list element of this process is removed and the entire log is contained in someone's phone.

That app works by exchanging a digital 'token' with every phone someone comes within Bluetooth range of over a fixed period.

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.

The server database will not be necessary because each phone will keep 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. 

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The two tech behemoths focused on a decentralised approach where there was no data being shared between devices and servers, helping to preserve privacy of users.

Also, the two companies are responsible for by far and away the two most popular mobile operating systems in the guise of iOS and Android. 

Being aware of all the security features and protocols that may make interaction between the different phones, they were able to devise a system that worked. 

NHS however, announced in April it would press on regardless of these inevitable issues and failed spectacularly.  

This was because the Bluetooth system developed by the NHS effectively went into 'sleep mode' when the phone screens were locked and developers couldn't fix the glitch. The app was abandoned a month after launch. 

In that time, Google and Apple released their software for free and it was picked up by 22 countries on the day it was released, on May 20

Perhaps unsurprisingly, trials revealed the Apple and Google technology can spot 99 per cent of close contacts using any type of smartphone — but it cannot currently tell how far away they are, officials claimed today. 

It took the UK until June 18 to admit this publicly and switch to the Google-Apple  model. 

Officials refused to reveal how much money has been spent on the now-scrapped app. 

The model, based on the Apple-Google system, uses, on average, two to three per cent of a phone's battery life each day, officials say. 

Once hailed as a vital part of the contact tracing system, the app is now an addition to the human system, officials say.

Dido Harding, the chair of NHS Test and Trace, said: 'There is no silver bullet when it comes to tackling coronavirus. 

'The app is a great step forward and will complement all of the work we are doing with local areas across the country to reach more people in their communities and work towards our vision of helping more people get back to the most normal life possible at the lowest risk.

'I am hugely grateful to the Isle of Wight, Newham and the NHS responders for playing their part.' 

HOW WILL THE NHS TEST & TRACE APP WORK? 

How does the contact logging work?

While the app is running Bluetooth technology will keep 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.

Will the app tell me what to do?

The app can only react to data that people put into it, and it will only ever offer guidance. If a user reports that they have symptoms of coronavirus - a new continuous cough, a fever, or a changed sense of smell or taste, they will be urged to self-isolate for 10 days from the start of the symptoms and to get tested.

If they test positive for Covid-19 at any time, they should report this to the app. The app then sends out an anonymous alert to everyone with whom that person has been within 2m (6'7") of for 15 minutes or more since they started feeling ill. 

That person may then be asked to self-isolate or to get tested if they feel unwell.

 

Why does it want my postcode? 

People who use the app will be asked to put in the first half of their postcode so they can be given the risk level for their local area, which will be low, medium or high.

This section will then have links to more information about specific rules if that area has a stricter lockdown than other parts of the country.

The first half of someone's postcode is too vague to pinpoint their personal location. They usually are the same for thousands of houses in the same area or for entire towns and villages. No location data is shared with the NHS or Government.

What is the QR code scanner for? 

People will be able to check in to places they visit using a QR code scanner which will keep of log of where they have been in case they are approached by contact tracers.

It is hoped this will help eliminate problems of people not remembering where they have been or where they may have put strangers at risk and have no way of contacting them. 

The system will be based on venue owners and event organisers ordering and printing their own QR codes online for people to scan when they arrive.

It is understood that this will create a log only for people's personal reference and that information will not be shared with venues or officials.

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