20,000 ex-NHS staff return to fight virus: UK PM

Thanking the doctors, nurses and other former professionals who have returned to the NHS, as well as the 750,000 members of the public who have volunteered to help the country through the pandemic, Johnson said in the video posted on Twitter: "We are going to do it, we are going to do it together," the BBC reported.

"One thing I think the coronavirus crisis has already proved is that there really is such a thing as society," he said, while contradicting the view of late Prime Minister Margaret Thatcher, that "there is no such thing as society".

Johnson, who is self-isolating after testing positive for the virus last week, said the public appeared to be obeying the restrictions set out by government to slow the spread of the virus, adding that train use was down 95 per cent and bus use down 75 per cent.

In another development, a Downing Street source confirmed on Monday that Dominic Cummings, Johnson's chief adviser, has developed symptoms of the virus and was self-isolating at home.

Health Secretary Matt Hancock has also tested positive for the disease.

Johnson's announcement on Monday comes a day after England's deputy chief medical officer Jenny Harries said on Sunday that it could be six months before life returns to "normal", the BBC reported.

Harries said this did not mean the country would be in "complete lockdown" for half a year, but distancing measures would be reviewed every three weeks and reduced gradually over a period of around three to six months.

However, she said it was "plausible" restrictions could continue for longer.

As of Monday, the UK has reported 19,784 confirmed coronavirus cases, with 1,231 deaths.