The Government is “optimistic” people will download a phone app to trace the spread of coronavirus, but has conceded the task to get the contact tracing system running remains “significant”.

Communities Secretary Robert Jenrick said he thought the “vast majority” of people would download the app and “play their part” – though insisted it was just one element of the plan to stop the spread.

Contact tracing will be central to the Government’s efforts in slowing the spread of coronavirus, and will involve alerting people who have been in contact with an infected person and asking them to self-isolate.

It has been used extensively in South Korea, Hong Kong and Germany, where outbreaks have been contained more quickly.

The Government intends to use an app and a phone team to carry out the tracing.

Mr Jenrick told the daily Downing Street press conference: “Contact tracing will rely on all of us in society playing our part but I’m optimistic about the prospects for that.

“This has been a national effort so far – if you think of the different measures that we’ve brought forward, the restrictions, the vast majority of people have got behind it and I think that they will do again when we are able to launch the app on a national scale.”

Deputy chief medical officer Dr Jenny Harries said to get contact tracing “up and running at scale and effectively” is “another significant task but (there is) lots of preparation under way”.

She said: “We need the whole population to work with us on this, it’s quite an exciting adventure.

“It’s a bit like social distancing, everybody has to do it together to get it to work…

“We need to be trialling it and we will be doing that very soon.”

The number of people who have died in hospitals, care homes and the wider community after testing positive for coronavirus in the UK as of 5pm on Friday rose to 28,131, up by 621.

The death toll has edged closer to that of Italy, which now stands at 28,710 and is the highest in Europe, according to data from Johns Hopkins University.

And the number of daily tests both concluded and sent out in the last 24 hours dropped to 105,937.

Of those, the number of people tested also fell – down to 63,667.

It comes as questions were raised over how tests are being counted after Health Secretary Matt Hancock said on Friday he had met his target for 100,000 Covid-19 tests per day.

Dr Harries said a breakdown of the more than 4,800 new cases exists but was unable to say what proportion were frontline workers, or people catching the virus in the community.

“We do look at this and there are a number of sub-groups nosocomial, so that’s infection spread in care settings and in care homes, where we are absolutely focusing on that because we are looking for any opportunities to interrupt transmission and make sure people are kept safe.”

Dr Harries also said:

– People will have to carefully consider how they travel to outdoor spaces as lockdown restrictions are eased – and should preferably avoid a pub visit on the way.

– Officials “don’t have enough information yet” to know whether people can catch coronavirus more than once, and signs of immunity could vary from patient to patient.

– There are “some signs” that younger children are potentially less likely to transmit Covid-19, although the quality of the evidence for this is “difficult”.

Mr Jenrick announced a £76 million package of support for “the most vulnerable in society” including domestic violence victims and rough sleepers.

He said more than 5,400 rough sleepers known to councils have been offered safe accommodation in the past month, and announced that Dame Louise Casey will lead a new taskforce to tackle the issue.