It is “difficult to pinpoint” where those infected with Covid-19 picked up the virus, a key Government doctor has said – as thousands of positive cases continue to be recorded despite lockdown measures being adhered to.

England’s deputy chief medical officer Dr Jenny Harries told a Downing Street briefing that there are “multiple exposures” for the public, as the virus is now more widespread in the community.

But, when looking at a chain of transmissions, Dr Harries told reporters that people’s homes were found to be a “very strong environment” for finding linked cases.

Asked about transmission in the community, Dr Harries said: “It’s very difficult to say precisely where an individual got their disease because we’re exposed to multiple exposures all the time and at a time of a pandemic where an infection is fairly widespread, it’s difficult to pinpoint that.

“We can look in some ways, so for example looking at different transmissions in a chain of transmission, and seeing where the most risks are.

“And actually, when we do that, most of the transmissions are at home, so the home environment is a very strong environment for finding linked cases.”

There are “really good” ongoing genomics studies investigating chains of Covid-19 transmission, Dr Harries added.

At the press conference on Thursday, Dominic Raab said that some 206,715 people have now tested positive for the virus – an increase of 5,614 cases since the day before.

The Foreign Secretary said that overall the infection rate was down across the country and “particularly in the community”.

However, he acknowledged there were “specific concerns” on infections in hospitals and care homes.

“We’re not complacent for a moment in those two settings but we do have a plan that we’re delivering to bring it right down,” he added.

On healthcare settings, Dr Harries told the briefing that there had to be a focus on care home staff.

“We need to focus equally not just on the residents but on the staff as well because these are quite closed communities,” she said.

“We have been talking about the R in the community, where everybody has done so well to bring that number down, but of course workers who are working in care and health settings also are part of their local communities.

“So we need to make sure that we address infection and prevention control measures, and really make them robust.”

The R value – which refers to the number of people who can expect to contract coronavirus from an infected person – has risen in the last week, driven by transmission in care homes.