Video report by ITV News Science Editor Tom Clarke
A coronavirus contact-tracing app developed by the NHS will be trialled on the Isle of Wight from Tuesday, the health secretary has said.
Matt Hancock, speaking at the government's daily coronavirus press conference, said with Covid-19 testing capacity now over 100,000, it is now time to "start implementing the next part of our plan; track and trace".
The health secretary said the 24 hours up to 9am Monday saw the smallest rise in coronavirus deaths "since the end of March".
There have now been at least 28,734 coronavirus related deaths, an increase of 288 from the figure released yesterday.
With the infection rate slowing (the R number) and the test capacity growing Mr Hancock said the government now plans to "keep R down".
He said an "army" of 18,000 "human contact tracers" are being hired to help with the tracking and tracing, who will work in conjunction with the NHS contact tracing app.
Setting out the new test, track and trace programme, Mr Hancock said it would “hunt down and isolate the virus so it is unable to reproduce”.
“Crucially, test, track and trace allows us to take a more targeted approach to lockdown while still safely containing the disease,” he said.
“Creating this system is a huge national undertaking of unprecedented scale and complexity.”
He said the app - developed by NHSX, the technology arm of the health service - "can help us deliver test track and trace on the mass scale that we need across the country".
The app has already been tested in closed conditions at an RAF base and from Tuesday NHS staff on the Isle of Wight will be able to download the app.
How the new NHS contact-tracing app works:
From Thursday each one of the 80,000 households on the island "will get a letter from the chief nurse with comprehensive information about the trial", Mr Hancock said.
He said the letter will ask people to on the island to download the app and inform it if they begin experiencing Covid-19 symptoms.
The government is using the Isle of Wight as a test, before rolling the app out on "mass scale" across the country by mid-May.
When someone reports symptoms through the app, it will detect any other app users that the person has been in "significant contact" with over the past few days, including unknown contacts such as someone they may have sat next to on public transport.
Battery conserving bluetooth technology will be used to work out which other app users people have been in contact with.
The app will be able to anonymously alert these contacts and provide advice, including how to get a test to confirm whether or not they do have Covid-19.
ITV News Science Editor Tom Clarke on the UK's coronavirus situation:
People will be able to order home testing kits via the app.
Mr Hancock said the Isle of Wight was chosen to trial the project because it has a single NHS Trust that covers all NHS services on the island.
Being an island with a small population means the trial can be carried out in "proper scientifically controlled conditions".
Mr Hancock said test, track and trace was aimed at making sure the number of cases continued to decline and the infection rate of coronavirus remained below one.
“Test, track and trace becomes more effective the lower the number and then we want to keep the number going down by keeping the R below one, the rate of infection,” he said.
The deputy chief medical officer for England, Professor Jonathan Van-Tam said "if uptake and use is widespread it will give us the greatest room for manoeuvre to ease other social distancing measures".
“Our goal is not simply to flatten the curve, it is to get the occurrence of Covid-19 infections to very low levels.”
But he warned "this trial does not mean the end of social distancing on the Isle of Wight or anywhere else for that matter".
Data will only ever be used for NHS care, management, evaluation and research, Mr Hancock said, and the NHS will comply fully with the law around its use, including the Data Protection Act.
He said social distancing rules will only be changed once the government's five tests (below) have been met.
Earlier on Monday Prime Minister Boris Johnson posted a video saying easing the rules now would be the "worst thing we could do".
Last week he said he would soon be setting out a "road map" of how lockdown could be eased, but it has now been suggested that will not happen until Sunday.
In the video message on Twitter he said the UK could only move to the "second phase of this conflict" once the "five tests" had been met.
Despite the daily increase in deaths being “lower than at any point since the end of March”, Mr Hancock pointed out that “reported figures tend to be lower over the weekend so we do expect that number to rise”.
Prof Van-Tam said there had been a “steady decline” in the numbers of hospital patients with coronavirus and a “slow and consistent decline” in the numbers of deaths.
However he said that the numbers of new cases of people testing positive for the disease needed to come down further.
Prof Van-Tam said the “overwhelming majority” of people who had recovered from Covid-19 were found to have antibodies in their bloodstream but it was not yet known for sure whether they would be immune from a second case of the disease or for how long the antibodies would last.
He said “we just haven’t had this disease around on the planet in humans for long enough” to know whether those who had recovered were immune.
“We can’t make the science go any faster than how quickly our bodies go in terms of maintaining the antibodies,” he said.
“Like everybody else in the world we just have to be patient and cautious until we get those answers.”
Watch the press conference in full: