Police officers outside St Thomas' Hospital in central London as Prime Minister Boris Johnson was moved to intensive care after his coronavirus symptoms worsened. (Photo by Victoria Jones/PA Images via Getty Images)

  • Boris Johnson spent the night in an intensive care unit at St Thomas' Hospital in London, after his condition badly deteriorated.
  • The Prime Minister, who was admitted to hospital on Sunday, has received oxygen treatment but is not yet on a ventilator, Downing Street indicated.
  • The UK Foreign Secretary Dominic Raab will continue to deputise for the prime minister in his absence.
  • Johnson's Cabinet vow to continue to fight "this invisible enemy" while Johnson is treated.
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UK Prime Minister Boris Johnson has spent the night in an intensive care unit after his condition badly deteriorated on Monday.

Johnson, who was admitted to hospital on Sunday with "persistent" symptoms of Covid-19, the illness caused by the coronavirus, was moved into intensive care at around 19:00 GMT on Monday.

He has been given oxygen treatment but has not yet been placed on a ventilator, Downing Street indicated on Tuesday morning.

"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," his spokesman said in a statement on Monday evening.

"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."

Johnson's spokesman said that the prime minister was moved into intensive care as a precautionary measure in case he needed ventilation.

The Times of London reported sources inside the hospital suggesting that the prime minister "needed four litres of oxygen in intensive care" but had not yet been intubated - the process by which a tube is inserted into the windpipe prior to ventilation.

The paper reports that "the normal threshold for intensive care is 15 litres, suggesting that he was in better health than such patients generally."

Dominic Raab, the UK's foreign secretary, is standing in for Johnson while he is treated.

Raab told the BBC that he would deputise for the prime minister "where necessary," adding that "there is an incredibly strong team spirit behind the prime minister

Cabinet Secretary Sir Mark Sedwill broke the news to the rest of the Cabinet via a video call, Sky News reported.

One minister who was present in the meeting described it as a "truly shocking" moment, according to the Times of London.

The UK's chancellor of the Duchy of Lancaster Michael Gove told the BBC that the whole cabinet would lead the country's response to the virus in Johnson's absence.

"We're all working together to implement the plan that the prime minister set out to make sure we can marshall all the resources of government and this country to fight this invisible enemy," Gove said.

Several of Johnson's senior aides are also experiencing symptoms of the virus.

Johnson spent over a week in self-isolation after developing symptoms of COVID-19 before he was taken to the hospital on Sunday for tests.

As of Monday morning, Downing Street had insisted that the prime minister was still running the UK government.

Johnson's spokesman had said the prime minister was in "good spirits" and was "comfortable" after spending the night at the central London hospital.

However, his condition significantly worsened later in the day, forcing doctors to move him into intensive care.

Johnson receives warm wishes from around the world

Johnson received warm wishes from around the world and across the political spectrum.

President Trump told a press briefing that "Americans are all praying for his recovery," adding that "he's been a very good friend".

He added that his administration had contacted "all of Johnson's doctors" and told them that he had asked two unnamed medical companies who work on treatments for Aids and Ebola to offer the prime minister support.

French President Emmanuel Macron said that he sent "all my support to Boris Johnson, to his family and to the British people at this difficult moment".

Keir Starmer, the leader of the opposition Labour Party, described the news as "terribly sad."

"All the country's thoughts are with the Prime Minister and his family during this incredibly difficult time," he tweeted.

Former Prime Minister David Cameron tweeted: "Thinking of @BorisJohnson and his family tonight. Get well soon. You are in great hands and we all want you safe, well and back in @10DowningStreet."

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