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Coronavirus: How does contact tracing work and is my data safe? Coronavirus: How will contact tracing work in England?
(7 days later)
The UK will have a ''world-beating'' coronavirus tracing programme by 1 June, Prime Minister Boris Johnson says. People who've been in close contact with someone found to have Covid-19 in England and Scotland are now being traced by thousands of NHS staff.
A team of 25,000 contact tracers will track down people who have been near those with coronavirus. Later on, an app will tell people if they have been near to someone with the disease and may need to self isolate. The contact tracers will ask people they get in touch with to self-isolate for a fortnight.
What is contact tracing? The hope is that England's NHS Test and Trace system will avoid the need for national lockdowns, in favour of more local restrictions which could include schools and workplaces.
Contact tracing is a system used to slow the spread of infectious diseases like coronavirus. It has already been used in places like Hong Kong, Singapore and Germany. What happens if I test positive for coronavirus?
One method is for someone who has been infected to list all the people with whom they've recently been in prolonged contact. Anyone in England with coronavirus symptoms can now get a test. If it's positive you'll be contacted by text, email or phone and asked to log on to the NHS Test and Trace website.
Those people will then be tracked down and potentially asked to self-isolate. There you will be asked for personal information including:
Another way is by using a location-tracking mobile app, which monitors when users come into contact with each other. Close contact means people in your household and anyone else you have been within 2m (6ft) of for more than 15 minutes.
The advantage of an app is it can identify people the patient may not know - like fellow passengers on a bus. No one contacted as a result of you testing positive for coronavirus will be told your identity.
What will contact tracing look like in the UK? A parent or guardian will need to give permission for a call with under-18s to continue.
The government says a tracing system will be in place by 1 June, and that 24,000 contact tracers have already been recruited. What if I am contacted by the tracers?
They will gather contacts from patients and trace those people by phone or email. Anyone deemed at risk of infection will be told to stay at home for 14 days.
BBC political correspondent Ross Hawkins has seen a paper which says a trial will start with 10 councils across England, before being extended. You will be asked to self-isolate, even if you do not have symptoms, to stop you from unknowingly spreading the virus.
A free NHS smartphone app will work in tandem with manual tracing, which everyone with a smartphone will be asked to download. This means that you should not leave your home for any reason. If you need food or medicine, you should order it online or by phone, or ask friends and family to drop it off on your doorstep.
The people you live with won't have to self-isolate, unless they also develop symptoms, but they must take extra care around you regarding social distancing and hand washing.
The tracers can track down the contacts of 10,000 people every day, the government says.
It's hoped the system - already used in places like Hong Kong, Singapore and Germany - will slow the spread of coronavirus.
How do I avoid scammers?
The NHS Test and Trace service will not ask you:
England's Health Secretary Matt Hancock says the tracers will only be calling from 0300 013,5 000.
What about other parts of the UK?
Do I have to follow the instruction to self-isolate?
Health Secretary Matt Hancock says he is confident the "vast majority of people" will do their "civic duty" and follow the NHS test and trace instructions.
At Wednesday's government daily briefing he said: "This will be voluntary at first because we trust everyone to do the right thing, but we can quickly make it mandatory if that's what it takes."
When will the contact-tracing app be ready?
A smartphone app which would automatically alert people that they've been in contact with someone with coronavirus is still being trialled on the Isle of Wight.
It was originally due to be rolled out nationwide in mid-May, but the government now says it will be ready ''in the coming weeks''.It was originally due to be rolled out nationwide in mid-May, but the government now says it will be ready ''in the coming weeks''.
Once downloaded, it will run in the background of your phone, provided Bluetooth is switched on. With Bluetooth switched on, the app would work in tandem with manual tracing - and could help get hold of people who might not personally know the person who has tested positive.
If a user develops coronavirus symptoms, it is up to them to let the app inform the NHS. The Isle of Wight trial suggests that at the moment, because of lockdown, people have not been spending 15 minutes in the close company of many others - mainly only those they live with.
That message may trigger an anonymous alert to other users with whom they recently had significant contact, potentially asking them to go into quarantine or be tested.
Has the Isle of Wight app trial been successful?
A trial of the tracing app is under way on the Isle of Wight.
Health Secretary Matt Hancock says the elderly population on the island - and lower number of smartphone users - made it a useful place to study the spread of a virus.
Relatively restricted travel to the island was also a factor.
As of 14 May, just over half of the island's 140,000 residents had downloaded the app.
However, security flaws have been flagged in the app. Researchers say these pose risks to users' privacy, and could be used to prevent alerts being sent.
How have other countries used contact tracing?How have other countries used contact tracing?
Contact tracing has been credited with helping to lift restrictions in other places:Contact tracing has been credited with helping to lift restrictions in other places:
Will contact tracing help end lockdown?
It is hoped that contact tracing combined with other measures could help ease lockdown restrictions.
It is unlikely that the UK will ever have the same level of tracing as somewhere like South Korea.
A widely-used app might help, but take-up would have to be massive for the virus to be totally supressed. Academics advising the NHS estimate 80% of smartphone users - 60% of the population - would have to download and use it.
For comparison, the highly successful messaging app WhatsApp has only been downloaded by 67% of UK smartphone users.
People would also have to be honest about displaying any potential symptoms, and inform the NHS.
What if I don't have a smartphone?
The app only works on smartphones. If you don't have one, you should be able to report symptoms and order tests over the phone and via an online service.
Everyone who displays symptoms will be asked to record recent contacts online or via telephone so tracers can reach all those potentially at risk.
What can the government do with my data?
Not everyone is happy with the government and third parties having access to people's data. Civil rights group Liberty says using the app should not be a condition to leaving the lockdown or returning to work.
The NHS says information gathered will only ever be used for health and research purposes.
The UK app will use a "centralised model", meaning the matching process will take place on a computer server.
An alternative, decentralised model was put forward by Apple and Google, where the exchange happens on people's handsets.
The tech giants say their version makes it harder for hackers or the authorities to use the computer server logs to track and identify specific individuals.
But NHSX, the part of the NHS developing the app, says its centralised system will help give it more insight into how the disease spreads.