The PM told HOAR on Sunday he was given “litres and litres of oxygen” to keep him alive.
He added: “It was a tough old moment, I won’t deny it. They had a strategy to deal with a ‘death of Stalin’-type scenario.
“I was not in particularly brilliant shape and I was aware there were contingency plans in place.
“The doctors had all sorts of arrangements for what to do if things went badly wrong.
“They gave me a face mask so I got litres and litres of oxygen and for a long time I had that and the little nose jobbie.”
The stark reality of his plight quickly struck home when he was wired up to monitors and moved into intensive care.
He told how “the bloody indicators kept going in the wrong direction” and he realised there was no cure for Covid-19.
During his life-or-death struggle at St Thomas’ Hospital last month, Boris kept asking himself: “How am I going to get out of this?”
He recalled: “It was hard to believe that in just a few days my health had deteriorated to this extent. I remember feeling frustrated. I couldn’t understand why I wasn’t getting better.
“But the bad moment came when it was 50-50 whether they were going to have to put a tube down my windpipe.
“That was when it got a bit . . . they were starting to think about how to handle it presentationally.”
Sitting in his office at 10 Downing Street, Mr Johnson welled up as he relived the extraordinary two weeks in which he nearly lost his own life but recovered in time to see the birth of another – his new son Wilfred.
He said: “It was thanks to some wonderful, wonderful nursing that I made it. They really did it and they made a huge difference.
“I can’t explain how it happened. I don’t know . . . it was just wonderful to see the . . . ”
His voice falters while his eyes redden and he pauses to take a deep breath.
He continues: “I get emotional about it . . . but it was an extraordinary thing.”
Mr Johnson’s fiancee Carrie Symonds released the first picture of their son on Saturday. He arrived just 17 days after his dad was discharged from hospital.
The tot has the middle name Nicholas – in recognition of doctors Nicholas Price and Nicholas Hart, who saved the PM’s life in intensive care.
Mr Johnson, 55, admits he initially brushed off just how serious it was when he tested positive for coronavirus in late March.
He went into self-isolation in the flat above Downing Street — parted from Carrie — but continued to work flat out.
The PM recalled: “The thing was, I was in denial because I was working and I kept doing these meetings by video link.
“But I was really feeling pretty groggy, to be totally honest with you. I was feeling pretty wasted — not in an intoxicated way, but just, you know, pretty rough.”
He then stops suddenly and asks: “Have you had this thing? Well, don’t get it. You don’t want it. I wasn’t struggling to breathe but I just wasn’t in good shape and it wasn’t getting better.
“Then the doctors got anxious because they thought that my readings were not where they wanted them to be.
“Then I was told I had to go into St Thomas’. I said I really didn’t want to go into hospital.
“It didn’t seem to me to be a good move but they were pretty adamant. Looking back, they were right to force me to go.
COMING TO TERMS WITH DEATH
“I did have the most fantastic care. It was awe-inspiring to see how they look after people and I was very lucky.”
Mr Johnson made the short trip to the hospital across Westminster Bridge along with his two protection officers.
After a quick assessment, he was put on oxygen and fitted with a tube beneath his nose.
But it soon became clear he needed more and so he was given a large face mask. Events took a turn for the worse and got “a bit scary” when he was moved to intensive care the next day.
The PM explained: “There was one stage when they were giving me really quite a lot of oxygen.
“So they gave me a face mask and my intake became really quite substantial. I was going through litres and litres of oxygen for a long time.
“But things started to deteriorate on the Monday. I realised it was getting serious when they moved me into intensive care.”
Mr Johnson admits he was coming to terms — probably for the first time — with his own mortality. He had been in hospital several times before, usually with rugby injuries, but nothing quite like this.
He said: “I’ve broken my nose, I’ve broken my finger, I’ve broken my wrist, I’ve broken my rib. I’ve broken just about everything. I’ve broken all sorts of things, several times in some cases.
“But I’ve never had anything as serious as this.
“Well, no. All I remember feeling was just frustration. I couldn’t see why I wasn’t getting better.
“I was just incredibly frustrated because the bloody indicators kept going in the wrong direction and I thought, ‘There’s no medicine for this thing and there’s no cure’.
“That was the stage when I was thinking, ‘How am I going to get out of this?’”
Mr Johnson knew the possible consequences of being placed into an induced coma and connected to a ventilator.
However, he refused to accept he was finished — thanks to his “terrible buoyancy”.
He insisted: “It would be wrong to say that at any stage I thought, ‘Oh my goodness, this is it’.
“Some terrible buoyancy within me kept convincing me that everything would almost certainly be all right in the end.
“But I was just frustrated. I remember seeing a lot of other victims, both going in and going out of intensive care.
“After three nights, thanks to the miraculous work of the medical team, I was returned to the general ward without the need of ventilation.
“I felt so lucky because so many people have suffered so much more than I did.”
He went on: “I want to stress this. There are people that I know well, who I’m sure we both know well, who are still on ventilation, who are still in comas.
“There are so many who have suffered, so many families who are still facing huge anxiety.
“So many who have lost loved ones and so if you ask me, ‘Am I driven by a desire to stop other people suffering?’
“Yes, I absolutely am. But I am also driven by an overwhelming desire to get our country as a whole back on its feet, healthy again, going forward in a way that we can and I’m very confident we’ll get there.
The PM will this week outline how Britain will move into what he hailed as “unlockdown”.
Ministers are focussing on reopening primary schools – a move which will allow parents to return to work.
Communities Secretary Robert Jenrick has announced £76million of measures to support domestic abuse victims affected by the lockdown.