Prime Minister Boris Johnson is "in good spirits" after spending the night in intensive care being treated for coronavirus, No 10 has said.
A spokesman said Mr Johnson, 55, was stable overnight and is being given oxygen and is not on a ventilator.
It comes as Cabinet Office minister Michael Gove became the latest politician to self-isolate after a family member showed symptoms.
Mr Gove said he did not have symptoms and will continue working at home.
Mr Johnson was admitted to St Thomas' Hospital in central London with "persistent symptoms" of Covid-19 on Sunday and was moved to intensive care on Monday at 19:00 BST after his symptoms worsened.
In a statement on Tuesday, a Downing Street spokesman said: "The prime minister has been stable overnight and remains in good spirits. He is receiving standard oxygen treatment and is breathing without any other assistance.
"He has not required mechanical ventilation or non-invasive respiratory support."
A ventilator takes over the body's breathing process when disease has caused the lungs to fail.
Mr Johnson does not have pneumonia, Downing Street added.
The spokesman said that the mood in government is "determined", and ministers have a very clear plan set out by Mr Johnson for responding to the pandemic.
The prime minister's weekly audience with the Queen will not go ahead although she will be kept regularly informed about his condition, the spokesman added.
Speaking to BBC Radio 4's Today programme, Mr Gove pledged that if there is any change in his condition "No 10 will ensure the country is updated".
Dominic Raab, the foreign secretary, has taken over leading the UK government while Boris Johnson is in hospital with coronavirus. The former lawyer was born in 1974, and is the son of a Czech refugee who fled the Nazis in 1938. He studied at both Oxford and Cambridge, and when working for the Foreign Office his job was to lead a team attempting to bring suspected war criminals to justice at The Hague.
A vocal supporter of Britain’s move to leave the EU, Raab was briefly the Brexit secretary under Johnson’s predecessor Theresa May, but resigned after saying he could not agree to the withdrawal deal that had been struck between her government and the EU.