A total of 6,159 patients have died in hospital after testing positive for coronavirus in the UK as of 5pm on Monday, the Department of Health said, up by 786 from 5,373 the day before.
The number is different from the total deaths reported by England, Scotland, Wales and Northern Ireland, due to differences in the way data is collated.
According to each country’s health authority, there were an additional 758 deaths in England, 74 in Scotland, 19 in Wales and three in Northern Ireland.
His coronavirus symptoms have worsened and Downing Street said he was moved to the unit as a precaution, should he need a ventilator to help him breathe.
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A spokesman said: “Since Sunday evening, the prime minister has been under the care of doctors at St Thomas’ Hospital, in London, after being admitted with persistent symptoms of coronavirus.
“Over the course of this afternoon, the condition of the prime minister has worsened and, on the advice of his medical team, he has been moved to the intensive care unit at the hospital.
“The PM has asked foreign secretary Dominic Raab, who is the first secretary of state, to deputise for him where necessary.
“The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication.”
There has been an outpouring of messages supporting the PM and his pregnant fiancée, Carrie Symonds, who herself has been recovering from coronavirus symptoms.
Raab said on Monday night: “The government’s business will continue.
“The prime minister is in safe hands with that brilliant team at St Thomas’ hospital, and the focus of the government will continue to be on making sure that the prime minister’s direction, all the plans for making sure that we can defeat coronavirus and can pull the country through this challenge, will be taken forward.”
He added: “There’s an incredibly strong team spirit behind the prime minister, and making sure that we get all of the plans the prime minister’s instructed us to deliver, to get them implemented as soon as possible.
“And that’s the way it will bring the whole country through the coronavirus challenge that we face right now.”
Another member of the government has also self-isolated due to the coronavirus. Chancellor of the Duchy of Lancaster and Cabinet Office minister Michael Gove has taken the step after a member of his family displayed coronavirus symptoms, although is reportedly not showing any himself.
In the last two weeks, health secretary Matt Hancock announced he had tested positive for coronavirus while chief medical adviser Chris Whitty and the senior adviser to Boris Johnson, Dominic Cummings, went into self-isolation after displaying symptoms.
Globally, there are more than 1.3 million confirmed coronavirus cases although the real number is likely to be much higher because of the way countries test for the virus.
There have been more than 75,000 officially recorded deaths according to Johns Hopkins University, with more than 40,000 of those coming from Italy, Spain, France and the UK. There have also been more than 289,000 recoveries.
China, where the outbreak began, has recorded no new cases over a 24-hour period but there have been doubts about the authorities’ reporting there.