Speaking at the daily coronavirus briefing, Mr Raab said Mr Johnson remained in “good spirits” and was breathing without assistance.
He also described the PM as not only a colleague – but “also a friend”.
Later in the evening, No 10 said the PM remained in critical care but his condition was “stable”.
It is understood there will be no further update on Mr Johnson’s condition until Wednesday.
Speaking at the daily coronavirus briefing, Mr Raab, who is deputising for the PM, said Mr Johnson was not only a boss but “also a friend”.
“All of our thoughts and prayers are with the prime minister at this time, with Carrie, and with his whole family.
“And I’m confident he’ll pull through because if there’s one thing I know about this prime minister, he’s a fighter. And he’ll be back at the helm, leading us through this crisis in short order.”
It comes as the number of coronavirus hospital deaths in the UK rose to 6,159 – a record increase of 786 in a day, the Department of Health and Social Care said, compared with 439 on Monday.
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 evening after his symptoms worsened.
Mr Raab said the prime minister was receiving standard oxygen treatment and breathing without any assistance, such as mechanical ventilation or non-invasive respiratory support.
Amid questions about what his role will entail, the foreign secretary said he was standing in for the prime minister “whenever necessary”, including leading the daily meetings of the coronavirus “war cabinet”.
Mr Raab, who chaired the government’s daily coronavirus meeting on Tuesday, said he had “total confidence” in the arrangements Mr Johnson had put in place.
“Well first of all, decision making by government is made by collective cabinet responsibilities, so that is the same as before,” the foreign secretary said.
“But we’ve got very clear directions, very clear instructions from the prime minister, and we’re focused with total unity and total resolve on implementing them so that when he’s back, I hope in very short order, we will have made the progress that he would expect and that the country would expect.”
Earlier, Buckingham Palace said the Queen had sent a message to Mr Johnson’s family and his partner, Carrie Symonds, saying she was thinking of them, and wished the PM a full and speedy recovery.
Prince William also tweeted a personal message of sympathy to the PM’s family, signing it off with his initial “W”, while his father, the Prince of Wales, sent a message from himself and the Duchess of Cornwall wishing Mr Johnson a “speedy recovery”, Clarence House said.
Source : Upday news, BBC news