Boris Johnson remains ‘stable’ in hospital with coronavirus symptoms after spending the night in intensive care.
The UK prime minister had already been at St Thomas’ Hospital in central London for tests and observation since Sunday, but his doctors later advised he be admitted to intensive care after he experienced breathing difficulties.
Johnson’s official spokesman said he had been receiving “standard oxygen treatment” but had not required a ventilator to assist his breathing and does not have pneumonia.
The Queen has sent a message to Johnson's family and his pregnant partner Carrie Symonds, saying they were in her thoughts and that she wished him a full and speedy recovery, Buckingham Palace said.
The Duke of Cambridge and the Prince of Wales and Duchess of Cornwall have also sent messages wishing Johnson a “speedy recovery”.
Britons have been urged on social media to “Clap for Boris” outside their homes on Tuesday evening.
The PM was understood to be conscious when he was moved to intensive care at about 7pm on Monday, as a precaution should he require ventilation to aid his recovery.
"The prime minister has been stable overnight and remains in good spirits," his spokesman said on Tuesday.
"He is receiving standard oxygen treatment and breathing without any other assistance. He has not required mechanical ventilation or non-invasive respiratory support."
His spokesman rejected claims that Number 10 had sought to hide the seriousness of his condition from the media.
Meanwhile, former prime minister David Cameron told ITV News: “All of us are praying for Boris and thinking of him and praying and thinking of his family.
“Boris is very tough, very resilient, very fit person, I know that from facing him on the tennis court and I’m sure he’ll come through this.”
His absence leaves a vacuum in leadership at a crucial time in the UK’s response to the COVID-19 pandemic, which so far has killed more than 5,300 patients.
Foreign secretary Dominic Raab will deputise for Johnson “where necessary”, on the prime minister’s instruction.
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Raab could be set to lead the country in the battle against coronavirus for some time, with the PM unable to resume work for an extended period.
Johnson, 55, was admitted to hospital on Sunday after his coronavirus symptoms had persisted for 10 days, for what Downing Street said were precautionary tests.
But in a dramatic statement at just after 8pm on Monday, a spokesman announced: “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.”
When it became clear that he had to be moved to intensive care, the prime minister told an aide that Raab should deputise for him.
The spokesman confirmed that Johnson had been unable to speak directly to Raab since he has been in hospital.
If Raab were to fall ill, under the established Cabinet order of precedence he would be replaced by chancellor Rishi Sunak.
Senior Cabinet minister Michael Gove has been forced to self-isolate, because a member of his family was showing symptoms.
The prime minister’s admission to intensive care raised concerns that he had been pushing himself too hard, continuing to lead the work of government while in self-isolation.
However, former Tory Party leader Sir Iain Duncan Smith said it was natural that he should want to carry on for as long as he could.
“The truth is, he’s prime minister. He was elected to run this country, and no prime minister is going to suddenly say ‘Look, I’m not well, I’m just gonna let somebody else do it’.”
Johnson’s condition means his fiancée, who is pregnant with their first child, is unable to visit him in hospital.
She said at the weekend that she is “on the mend” after herself being forced to self-isolate after displaying symptoms of the disease.
Johnson ‘very likely to need ventilator’
The prime minister is “extremely sick” – with many coronavirus patients who need intensive care requiring invasive ventilation, an expert has said.
Derek Hill, professor of medical imaging at University College London (UCL), said the PM could be given a breathing aid known as continuous positive airway pressure (CPAP), which bridges the gap between an oxygen mask and full ventilation.
CPAP uses pressure to send a blend of air and oxygen into the mouth at a steady rate, thereby boosting the amount of oxygen that enters the lungs.
But Prof Hill said many COVID-19 patients eventually “progress to invasive ventilation”.
This is for people whose illness is so severe they are struggling or unable to breathe for themselves.
A mechanical ventilator either does all the breathing for the patient, or assists the patient’s own breathing.
Prof Hill said it was unclear whether Mr Johnson was breathing on his own, or with the help of a ventilator.
PM and partner Carrie Symonds receive outpouring of support
World leaders and Johnson’s colleagues from across British politics were quick to offer their support to the prime minister and his family within minutes of the news on Monday night.
Newly-elected Labour leader Keir Starmer said it was “terribly sad news” and he was thinking of the prime minister, while SNP House of Commons leader Ian Blackford also wrote of his concern.
The chancellor, Rishi Sunak, tweeted he was thinking of the prime minister and his pregnant fiancée, Carrie Symonds, who previously said she was on the mend after suffering from coronavirus symptoms.
Keeping fighting Boris. Whole country behind you #BackBoris— Jeremy Hunt (@Jeremy_Hunt) April 6, 2020
Boris is one of the strongest people I know. Thinking of him, Carrie and his family tonight. Get well soon, the country needs you.— Sajid Javid (@sajidjavid) April 6, 2020
Sajid Javid, who resigned as chancellor earlier this year, and former leadership rival Jeremy Hunt added to the messages of concern.
And away from parliament, Labour mayor of London Sadiq Khan praised the St Thomas’ Hospital staff, where the PM is being treated, while Scottish first minister Nicola Sturgeon added to the outpouring of support.
Friends and opponents of times past also offered their support, with former prime minister David Cameron tweeting: “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.”
Buckingham Palace confirmed the Queen was being kept informed by Downing Street about the condition of Mr Johnson – the 14th prime minister of her reign.
My thoughts are with the PM and his family - sending him every good wish https://t.co/tjpadJq6bq— Nicola Sturgeon (@NicolaSturgeon) April 6, 2020
Internationally, US president Donald Trump added: “I want to send our very best wishes to a very good friend of mine and a friend to our nation, prime minister Boris Johnson.
“We’re very saddened to hear that he was taken into intensive care this afternoon and Americans are all praying for his recovery.
“He’s been a really good friend. He’s been really something very special: strong, resolute, doesn’t quit, doesn’t give up.
“But when you get brought into intensive care, that gets very, very serious with this particular disease,” he added.
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French president Emmanuel Macron was the first major leader to send his wishes, tweeting: “All my support to Boris Johnson, his family and the British people at this difficult time. I wish him well.”
Meanwhile, Spanish prime minister Pedro Sanchez tweeted his “solidarity and wishes” to his UK counterpart.
“These are difficult days for our countries, but from strength and unity, we will be able to win this battle. A hug to all the British people,” he added.
And Ireland’s deputy leader Simon Coveney added: “Everyone in Ireland is tonight wishing @BorisJohnson well. This is a difficult time for the UK and it’s Govt. We in #Ireland wish the PM a speedy recovery.”