Prime Minister Boris Johnson has been moved to intensive care in hospital after his coronavirus symptoms "worsened", Downing Street has said.
A spokesman said he was moved on the advice of his medical team and was receiving "excellent care".
Mr Johnson has asked Foreign Secretary Dominic Raab to deputise "where necessary", the spokesman added.
The prime minister, 55, was admitted to hospital in London with "persistent symptoms" on Sunday evening.
The Queen has been kept informed about Mr Johnson's health by No 10, according to Buckingham Palace.
BBC political correspondent Chris Mason said the prime minister was given oxygen late on Monday afternoon, before being taken to intensive care.
However, he has not been put on a ventilator.
A No 10 statement read: "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 [Monday] 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."
It continued: "The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication."
Mr Raab - who will later chair the government's daily Covid-19 meeting - said there was an "incredibly strong team spirit" behind the prime minister.
He added that he and his colleagues were making sure they implemented plans Mr Johnson had instructed them to deliver "as soon as possible".
"That's the way we'll bring the whole country through the coronavirus challenge," he said.
Labour leader Sir Keir Starmer described it as "terribly sad news".
"All the country's thoughts are with the prime minister and his family during this incredibly difficult time," he added.
Media playback is unsupported on your device
US President Donald Trump said Americans "are all praying for his recovery".
He described Mr Johnson as "a very good friend of mine and a friend to our nation" who is "strong" and "doesn't give up".
Mr Johnson was initially taken to hospital for routine tests after testing positive for coronavirus 10 days ago. His symptoms included a high temperature and a cough.
Earlier on Monday, he tweeted that he was in "good spirits".
Last night, on the advice of my doctor, I went into hospital for some routine tests as I’m still experiencing coronavirus symptoms. I’m in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe.
— Boris Johnson #StayHomeSaveLives (@BorisJohnson) April 6, 2020
End of Twitter post by @BorisJohnson
After very, very little information was shared today, the prime minister was taken into intensive care at around 19:00 BST.
We've been told he is still conscious, but his condition has worsened over the course of the afternoon.
And he has been moved to intensive care as a precaution in case he needs ventilation to get through this illness.
The statement from Downing Street makes clear he is receiving excellent care and he wants to thank all of the NHS staff.
But something important has changed, and he has felt it necessary to ask his foreign secretary to deputise for him where needs be.
That is a completely different message from what we have heard over the past 18 hours or so, where it was continually "the prime minister is in touch" and "he is in charge" - almost like everything is business as usual.
But clearly being in intensive care changes everything.
It comes as the number of coronavirus hospital deaths in the UK reached 5,373 - an increase of 439 in a day.
The Department of Health and Social Care said there were now 51,608 confirmed coronavirus cases.
Intensive care is where doctors look after the sickest patients - his admission to ICU is the clearest indication of how ill the prime minister is.
We do not know the full details of Mr Johnson's condition, but he is conscious and not being ventilated.
Not every patient in intensive care is ventilated, but around two-thirds are within 24 hours of admission with Covid-19.
This is a disease that attacks the lungs and can cause pneumonia and difficulty breathing.
This leaves the body struggling to get enough oxygen into the blood and to the body's vital organs.
There is no proven drug treatment for Covid-19, although there are many experimental candidates.
But the cornerstone of the prime minister's care will depend on getting enough oxygen into his body and supporting his other organs while his immune system fights the virus.
Chancellor Rishi Sunak said his thoughts were with the prime minister and his pregnant partner, Carrie Symonds, and that Mr Johnson would "come out of this even stronger".
Wales' First Minister Mark Drakeford called it "concerning news".
Mr Johnson's predecessor, Theresa May, and former Labour leader Jeremy Corbyn both said their thoughts were with him.
Mrs May noted that the "horrific virus does not discriminate".
The Taoiseach (Irish Prime Minister) Leo Varadkar wished Mr Johnson "a rapid return to health", and French President Emmanuel Macron said he hoped he "overcomes this ordeal quickly."
European Commission President Ursula von der Leyen also wished him a "speedy and full recovery".
For Archbishop of Canterbury Justin Welby, the news "deepens our compassion for all who are seriously ill" and those looking after them.
And Mayor of London Sadiq Khan tweeted that St Thomas' Hospital had "some of the finest medical staff in the world" and that the prime minister "couldn't be in safer hands".
Media playback is unsupported on your device
During the government's daily coronavirus briefing earlier on Monday, Mr Raab stressed that the prime minister had been continuing to run the government from hospital.
Asked whether that was appropriate, Mr Raab said Mr Johnson would "take the medical advice that he gets from his doctor".
"We have a team... that is full throttle making sure that his directions and his instructions are being implemented," he said.
The foreign secretary added that he had not spoken to the prime minister since Saturday.
On Saturday, Ms Symonds said she had spent a week in bed with the main symptoms. She said she had not been tested for the virus.
Health Secretary Matt Hancock, who also tested positive for the virus and spent time in self-isolation, offered "all possible best wishes to Boris Johnson and his loved ones".
"I know he will receive the best possible care from our amazing NHS," he tweeted.
Prime Minister Boris Johnson has been moved to intensive care in hospital after his coronavirus symptoms "worsened", Downing Street has said.
A spokesman said he was moved on the advice of his medical team and was receiving "excellent care".
Mr Johnson has asked Foreign Secretary Dominic Raab to deputise "where necessary", the spokesman added.
The prime minister, 55, was admitted to hospital in London with "persistent symptoms" on Sunday evening.
The Queen has been kept informed about Mr Johnson's health by No 10, according to Buckingham Palace.
BBC political correspondent Chris Mason said the prime minister was given oxygen late on Monday afternoon, before being taken to intensive care.
However, he has not been put on a ventilator.
A No 10 statement read: "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 [Monday] 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."
It continued: "The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication."
Mr Raab - who will later chair the government's daily Covid-19 meeting - said there was an "incredibly strong team spirit" behind the prime minister.
He added that he and his colleagues were making sure they implemented plans Mr Johnson had instructed them to deliver "as soon as possible".
"That's the way we'll bring the whole country through the coronavirus challenge," he said.
Labour leader Sir Keir Starmer described it as "terribly sad news".
"All the country's thoughts are with the prime minister and his family during this incredibly difficult time," he added.
Media playback is unsupported on your device
US President Donald Trump said Americans "are all praying for his recovery".
He described Mr Johnson as "a very good friend of mine and a friend to our nation" who is "strong" and "doesn't give up".
Mr Johnson was initially taken to hospital for routine tests after testing positive for coronavirus 10 days ago. His symptoms included a high temperature and a cough.
Earlier on Monday, he tweeted that he was in "good spirits".
Last night, on the advice of my doctor, I went into hospital for some routine tests as I’m still experiencing coronavirus symptoms. I’m in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe.
— Boris Johnson #StayHomeSaveLives (@BorisJohnson) April 6, 2020
End of Twitter post by @BorisJohnson
After very, very little information was shared today, the prime minister was taken into intensive care at around 19:00 BST.
We've been told he is still conscious, but his condition has worsened over the course of the afternoon.
And he has been moved to intensive care as a precaution in case he needs ventilation to get through this illness.
The statement from Downing Street makes clear he is receiving excellent care and he wants to thank all of the NHS staff.
But something important has changed, and he has felt it necessary to ask his foreign secretary to deputise for him where needs be.
That is a completely different message from what we have heard over the past 18 hours or so, where it was continually "the prime minister is in touch" and "he is in charge" - almost like everything is business as usual.
But clearly being in intensive care changes everything.
It comes as the number of coronavirus hospital deaths in the UK reached 5,373 - an increase of 439 in a day.
The Department of Health and Social Care said there were now 51,608 confirmed coronavirus cases.
Intensive care is where doctors look after the sickest patients - his admission to ICU is the clearest indication of how ill the prime minister is.
We do not know the full details of Mr Johnson's condition, but he is conscious and not being ventilated.
Not every patient in intensive care is ventilated, but around two-thirds are within 24 hours of admission with Covid-19.
This is a disease that attacks the lungs and can cause pneumonia and difficulty breathing.
This leaves the body struggling to get enough oxygen into the blood and to the body's vital organs.
There is no proven drug treatment for Covid-19, although there are many experimental candidates.
But the cornerstone of the prime minister's care will depend on getting enough oxygen into his body and supporting his other organs while his immune system fights the virus.
Chancellor Rishi Sunak said his thoughts were with the prime minister and his pregnant partner, Carrie Symonds, and that Mr Johnson would "come out of this even stronger".
Wales' First Minister Mark Drakeford called it "concerning news".
Mr Johnson's predecessor, Theresa May, and former Labour leader Jeremy Corbyn both said their thoughts were with him.
Mrs May noted that the "horrific virus does not discriminate".
The Taoiseach (Irish Prime Minister) Leo Varadkar wished Mr Johnson "a rapid return to health", and French President Emmanuel Macron said he hoped he "overcomes this ordeal quickly."
European Commission President Ursula von der Leyen also wished him a "speedy and full recovery".
For Archbishop of Canterbury Justin Welby, the news "deepens our compassion for all who are seriously ill" and those looking after them.
And Mayor of London Sadiq Khan tweeted that St Thomas' Hospital had "some of the finest medical staff in the world" and that the prime minister "couldn't be in safer hands".
Media playback is unsupported on your device
During the government's daily coronavirus briefing earlier on Monday, Mr Raab stressed that the prime minister had been continuing to run the government from hospital.
Asked whether that was appropriate, Mr Raab said Mr Johnson would "take the medical advice that he gets from his doctor".
"We have a team... that is full throttle making sure that his directions and his instructions are being implemented," he said.
The foreign secretary added that he had not spoken to the prime minister since Saturday.
On Saturday, Ms Symonds said she had spent a week in bed with the main symptoms. She said she had not been tested for the virus.
Health Secretary Matt Hancock, who also tested positive for the virus and spent time in self-isolation, offered "all possible best wishes to Boris Johnson and his loved ones".
"I know he will receive the best possible care from our amazing NHS," he tweeted.
Prime Minister Shinzo Abe said that "basic economic activity" will continue in Tokyo, Kanagawa, Saitama, Chiba, Osaka, Hyogo and Fukuoka, the seven affected prefectures, with public transport and supermarkets remaining open, but urged people to exercise social distancing and avoid unnecessary trips.
The state of emergency, which is expected to be formally announced at a press conference Tuesday,will last for approximately one month. The declaration comes as Japan reported 252 new cases of the coronavirus and seven more deaths Monday, bringing the total number of infections to over 4,600, with 91 deaths.
Abe has faced criticism for not activating emergency measures earlier, as experts warned the true number of cases could be far higher than the official statistics suggest, due to a lack of widespread testing.
Growing concerns
The Japanese capital Tokyo is among one of the country's worst hit areas, and on Monday doctors in the city declared a state of medical emergency, citing a possible collapse of the healthcare system.
Ozaki Haruo, president of the Tokyo Medical Association, told reporters Monday that the rising number of coronavirus cases could result in a shortage of beds and the spreading of the virus within hospitals, according to Japanese public broadcaster NHK.
When this happens, medical staff will be unable to provide services to critically ill patients, Ozaki said, adding that the next six weeks will be critical in preventing an "explosive spread" of the virus.
Japan only has seven intensive care beds for every 100,000 people, a fifth of the proportion available in the US.
Part of the problem is that authorities had previously been urging anyone with symptoms to go to hospital, putting additional strain on the health care system. However, Dr. Yoshihiro Takayama, an infectious diseases specialist at Okinawa Chubu Hospital, said that the authorities are preparing to shift to a new policy of requiring those with mild symptoms to "self-isolate at home."
Takayama was concerned however that the number of cases could be far greater than it appears from the official statistics, due to the paucity of testing nationwide.
As of last week, Japan had only conducted some 30,000 tests, compared with almost 400,000 carried out in neighboring South Korea.
"In some cases, the number of patients may be several times, or could be ten times more. I think it is necessary to use such imagination and prepare the medical system to deal with it," Takayama said. "The battle has only just begun."
The country is also facing a potential shortage of ventilators for the worst affected. As of February, Japan was estimated to have more than 22,000 ventilators, for a population of over 126 million, according to a report in NHK.
At least 40% of those ventilators are already in use, as officials scramble to ramp up production and source new machines from overseas.
Slow response
Japan, with strong economic and transport links to China, was among the first countries to report cases of the coronavirus. For a long time, an outbreak on board the Diamond Princess cruise ship, docked in Yokohama, was the worst outside mainland China.
Despite this long exposure to the virus, the country has been slow to take the kind of radical steps seen in many other parts of the world, and officials have faced accusations of deliberately dragging their feet to avoid greater damage to the economy after the postponement of the Tokyo Olympics, which is expected to cause a big hit.
But experts have warned that the failure to respond quickly could result in a far worse situation.
"Japan needs to have the courage to change, when we are aware we are on the wrong path," said Kentaro Iwata, an infection control specialist from Kobe University, who has repeatedly warned that Japan isn't doing enough to halt the spread of the virus. "We might see the next New York City in Tokyo."
Iwata said that the situation in the Japanese capital is comparable to that in New York, Spain and Italy just before they saw explosions in the number of cases, and he called on the government to conduct more widespread testing in order to get an idea of the true number of infections.
The Japanese government says its testing regime is adequate and suitably targeted to high risk cases.
"Testing people with a low probability of novel coronavirus would be a waste of resources," Japan's Health Ministry told CNN in a statement. "We ask people with some symptoms to stay home for a period of time."
A government panel warned last week that hospitals and medical clinics in Tokyo, Aichi, Kanagawa, Osaka and Hyogo were already stretched and that "drastic countermeasures need to be taken as quickly as possible."
Will Ripley reported from Tokyo, James Griffiths reported from Hong Kong. CNN's Yoko Wakatsuki and Emiko Jozuka contributed reporting from Tokyo.
Prime Minister Boris Johnson has been moved to intensive care in hospital after his coronavirus symptoms "worsened", Downing Street has said.
A spokesman said he was moved on the advice of his medical team and was receiving "excellent care".
Mr Johnson has asked Foreign Secretary Dominic Raab to deputise "where necessary", the spokesman added.
The prime minister, 55, was admitted to hospital in London with "persistent symptoms" on Sunday evening.
The Queen has been kept informed about Mr Johnson's health by No 10, according to Buckingham Palace.
BBC political correspondent Chris Mason said the prime minister was given oxygen late on Monday afternoon, before being taken to intensive care.
However, he has not been put on a ventilator.
A No 10 statement read: "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 [Monday] 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."
It continued: "The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication."
Mr Raab said there was an "incredibly strong team spirit" behind the prime minister.
He added that he and his colleagues were making sure they implemented plans Mr Johnson had instructed them to deliver "as soon as possible".
"That's the way we'll bring the whole country through the coronavirus challenge," he said.
Labour leader Sir Keir Starmer described it as "terribly sad news".
"All the country's thoughts are with the prime minister and his family during this incredibly difficult time," he added.
US President Donald Trump said Americans "are all praying for his recovery".
He described Mr Johnson as "a very good friend of mine and a friend to our nation" who is "strong" and "doesn't give up".
Mr Johnson was initially taken to hospital for routine tests after testing positive for coronavirus 10 days ago. His symptoms included a high temperature and a cough.
Earlier on Monday, he tweeted that he was in "good spirits".
Last night, on the advice of my doctor, I went into hospital for some routine tests as I’m still experiencing coronavirus symptoms. I’m in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe.
— Boris Johnson #StayHomeSaveLives (@BorisJohnson) April 6, 2020
End of Twitter post by @BorisJohnson
After very, very little information was shared today, the prime minister was taken into intensive care at around 19:00 BST.
We've been told he is still conscious, but his condition has worsened over the course of the afternoon.
And he has been moved to intensive care as a precaution in case he needs ventilation to get through this illness.
The statement from Downing Street makes clear he is receiving excellent care and he wants to thank all of the NHS staff.
But something important has changed, and he has felt it necessary to ask his foreign secretary to deputise for him where needs be.
That is a completely different message from what we have heard over the past 18 hours or so, where it was continually "the prime minister is in touch" and "he is in charge" - almost like everything is business as usual.
But clearly being in intensive care changes everything.
It comes as the number of coronavirus hospital deaths in the UK reached 5,373 - an increase of 439 in a day.
The Department of Health and Social Care said there were now 51,608 confirmed coronavirus cases.
Intensive care is where doctors look after the sickest patients - his admission to ICU is the clearest indication of how ill the prime minister is.
We do not know the full details of Mr Johnson's condition, but he is conscious and not being ventilated.
Not every patient in intensive care is ventilated, but around two-thirds are within 24 hours of admission with Covid-19.
This is a disease that attacks the lungs and can cause pneumonia and difficulty breathing.
This leaves the body struggling to get enough oxygen into the blood and to the body's vital organs.
There is no proven drug treatment for Covid-19, although there are many experimental candidates.
But the cornerstone of the prime minister's care will depend on getting enough oxygen into his body and supporting his other organs while his immune system fights the virus.
Chancellor Rishi Sunak said his thoughts were with the prime minister and his pregnant partner, Carrie Symonds, and that Mr Johnson would "come out of this even stronger".
Wales' First Minister Mark Drakeford called it "concerning news".
Mr Johnson's predecessor, Theresa May, and former Labour leader Jeremy Corbyn both said their thoughts were with him.
Mrs May noted that the "horrific virus does not discriminate".
The Taoiseach (Irish Prime Minister) Leo Varadkar wished Mr Johnson "a rapid return to health", and French President Emmanuel Macron said he hoped he "overcomes this ordeal quickly."
European Commission President Ursula von der Leyen also wished him a "speedy and full recovery".
For Archbishop of Canterbury Justin Welby, the news "deepens our compassion for all who are seriously ill" and those looking after them.
And Mayor of London Sadiq Khan tweeted that St Thomas' Hospital had "some of the finest medical staff in the world" and that the prime minister "couldn't be in safer hands".
Media playback is unsupported on your device
During the government's daily coronavirus briefing earlier on Monday, Mr Raab stressed that the prime minister had been continuing to run the government from hospital.
Asked whether that was appropriate, Mr Raab said Mr Johnson would "take the medical advice that he gets from his doctor".
"We have a team... that is full throttle making sure that his directions and his instructions are being implemented," he said.
The foreign secretary added that he had not spoken to the prime minister since Saturday.
On Saturday, Ms Symonds said she had spent a week in bed with the main symptoms. She said she had not been tested for the virus.
Health Secretary Matt Hancock, who also tested positive for the virus and spent time in self-isolation, offered "all possible best wishes to Boris Johnson and his loved ones".
"I know he will receive the best possible care from our amazing NHS," he tweeted.
Prime Minister Boris Johnson has been moved to intensive care in hospital after his coronavirus symptoms "worsened", Downing Street has said.
A spokesman said he was moved on the advice of his medical team and was receiving "excellent care".
Mr Johnson has asked Foreign Secretary Dominic Raab to deputise "where necessary", the spokesman added.
The prime minister, 55, was admitted to hospital in London with "persistent symptoms" on Sunday evening.
The Queen has been kept informed about Mr Johnson's health by No 10, according to Buckingham Palace.
BBC political correspondent Chris Mason said the prime minister was given oxygen late on Monday afternoon, before being taken to intensive care.
A No 10 statement read: "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 [Monday] 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."
It continued: "The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication."
Mr Raab said there was an "incredibly strong team spirit" behind the prime minister.
He added that he and his colleagues were making sure they implemented plans Mr Johnson had instructed them to deliver "as soon as possible".
"That's the way we'll bring the whole country through the coronavirus challenge," he said.
Labour leader Sir Keir Starmer described it as "terribly sad news".
"All the country's thoughts are with the prime minister and his family during this incredibly difficult time," he added.
Mr Johnson was initially taken to hospital for routine tests after testing positive for coronavirus 10 days ago. His symptoms included a high temperature and a cough.
Earlier on Monday, he tweeted that he was in "good spirits".
Last night, on the advice of my doctor, I went into hospital for some routine tests as I’m still experiencing coronavirus symptoms. I’m in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe.
— Boris Johnson #StayHomeSaveLives (@BorisJohnson) April 6, 2020
End of Twitter post by @BorisJohnson
After very, very little information was shared today, the prime minister was taken into intensive care at around 19:00 BST.
We've been told he is still conscious, but his condition has worsened over the course of the afternoon.
And he has been moved to intensive care as a precaution in case he needs ventilation to get through this illness.
The statement from Downing Street makes clear he is receiving excellent care and he wants to thank all of the NHS staff.
But something important has changed, and he has felt it necessary to ask his foreign secretary to deputise for him where needs be.
That is a completely different message from what we have heard over the past 18 hours or so, where it was continually "the prime minister is in touch" and "he is in charge" - almost like everything is business as usual.
But clearly being in intensive care changes everything.
It comes as the number of coronavirus hospital deaths in the UK reached 5,373 - an increase of 439 in a day.
The Department of Health and Social Care said there were now 51,608 confirmed coronavirus cases.
Intensive care is where doctors look after the sickest patients - his admission to ICU is the clearest indication of how ill the prime minister is.
We do not know the full details of Mr Johnson's condition, but he is conscious and not being ventilated.
Not every patient in intensive care is ventilated, but around two-thirds are within 24 hours of admission with Covid-19.
This is a disease that attacks the lungs and can cause pneumonia and difficulty breathing.
This leaves the body struggling to get enough oxygen into the blood and to the body's vital organs.
There is no proven drug treatment for Covid-19, although there are many experimental candidates.
But the cornerstone of the prime minister's care will depend on getting enough oxygen into his body and supporting his other organs while his immune system fights the virus.
Chancellor Rishi Sunak said his thoughts were with the prime minister and his pregnant partner, Carrie Symonds, and that Mr Johnson would "come out of this even stronger".
French President Emmanuel Macron tweeted that he hoped Mr Johnson "overcomes this ordeal quickly."
For Archbishop of Canterbury Justin Welby, the news "deepens our compassion for all who are seriously ill" and those looking after them.
And Mayor of London Sadiq Khan tweeted that St Thomas' Hospital had "some of the finest medical staff in the world" and that the prime minister "couldn't be in safer hands".
Media playback is unsupported on your device
During the government's daily coronavirus briefing earlier on Monday, Mr Raab stressed that the prime minister had been continuing to run the government from hospital.
Asked whether that was appropriate, Mr Raab said Mr Johnson would "take the medical advice that he gets from his doctor".
"We have a team... that is full throttle making sure that his directions and his instructions are being implemented," he said.
The foreign secretary added that he had not spoken to the prime minister since Saturday.
On Saturday, Ms Symonds said she had spent a week in bed with the main symptoms. She said she had not been tested for the virus.
Health Secretary Matt Hancock, who also tested positive for the virus and spent time in self-isolation, offered "all possible best wishes to Boris Johnson and his loved ones".
"I know he will receive the best possible care from our amazing NHS," he tweeted.
