World leaders have sent messages of support to Boris Johnson after the Prime Minister (PM) was taken to an intensive care unit - a special ward for patients who need extra support.
Mr Johnson is being cared for in a London hospital after his coronavirus symptoms worsened on Monday night.
An official spokesperson said the move was so he could be nearer to specialist equipment used to treat patients who need extra help.
On Tuesday they added that the PM was "in good spirits" after spending the night in the specialist ward.
Foreign Secretary Dominic Raab has been asked to take on the PM's duties while he is in hospital.
Mr Johnson tested positive for coronavirus on 27 March and had mild symptoms.
He was taken to hospital on Sunday for "routine tests" before it was announced on Monday he had been moved to the intensive care unit.
Earlier in the day he had posted a message on social media thanking NHS staff..
Presidents, prime ministers and religious leaders from all over the world have wished Mr Johnson well.
The First Ministers of Scotland, Wales and Northern Ireland and new Labour leader, Sir Keir Starmer were among those sending their good wishes and describing it as "sad news".
President Emmanuel Macron of France said he hoped that Mr Johnson would "rapidly overcome this ordeal" and US President Donald Trump said the prime minister was a "good friend of his", adding that Americans were praying for him.
Archbishop of Canterbury Justin Welby, Mayor of London Sadiq Khan, Irish Prime Minister Leo Varadkar and European Commission President Ursula von der Leyen are also among those to have sent messages of support.
Other members of Boris Johnson's top team have also been affected by coronavirus.
Michael Gove, the Minister for the Cabinet Office, has announced that he is going into self-isolation after showing symptoms.
Health secretary Matt Hancock, who is charge of the NHS, had to self-isolate for a week when he tested positive for coronavirus, as did one of his junior health ministers, Nadine Dorries. They are both recovered and back at work.
Professor Chris Whitty, England's Chief Medical Officer is also back at work this week after displaying symptoms and self-isolating for seven days.