Just one per cent of hospital beds are occupied by Covid patients, the head of the NHS has said, compared to one third at the peak of the pandemic.
Sir Simon Stevens said hospitals are in a "much better position" than they previously were, with far fewer patients who tended to be younger and more likely to recover.
NHS statistics show that Covid patients fill 993 of 96,000 hospital beds in England – just one per cent. At the peak of the second wave in January, there were more than 34,000 Covid patients in hospital, filling one in three beds.
Sir Simon told the NHS Confederation annual conference that the majority of hospital cases now were younger than previously, with these people having "much greater" chances of recovery.
He said the NHS was currently in a "much better position now than we were this time last year" because of the "protective wall" provided by vaccinations.
This time last year, there were around 4,000 Covid patients in hospital in England.
Sir Simon said: "At the moment, about one per cent of hospital beds in England are occupied by patients with a Covid diagnosis, and the age distribution has really flipped as a result of vaccination.
"Back in January, it was 60/40 – 60 per cent of beds occupied by people over 65, 40 per cent under 65. Now it's flipped to 30/70, so it's about 30 per cent occupied by people aged 65 and over 70 per cent by younger people, whose prospects are much greater."
Boris Johnson announced a four-week delay to the lifting of Covid restrictions on Monday after government scientists said it was not possible to determine whether the move would result in "unsustainable pressure on the NHS".
At a Downing Street press conference, Prof Chris Whitty, England's chief medical officer, said the NHS could "run into trouble" if the number of people being admitted to hospital with the virus continued on an "exponential path".
He said the four-week delay to unlocking "will reduce significantly the risk of a very high peak which could cause significant problems in terms of pressure on the NHS".
A paper by the Scientific Advisory Group for Emergencies (Sage), dated June 9, said: "Taking step four of the road map on June 21 carries significant uncertainty and risk. It is not possible at this point to determine whether this would result in unsustainable pressure on the NHS."
Prof Graham Medley, a member of Sage and SPI-M, a sub-group that also advises the Government on its Covid response, said there would still be a large amount of uncertainty in the data by the time new projections are made for July 19.
He said the models used to delay the June 21 date, which he helped make, had a large amount of uncertainty because of various unknowns such as the true transmissibility of the Indian or delta Covid variant and the effectiveness of the vaccines against the strain.
"In three weeks, how much uncertainty will remain? I suspect that the answer is more than we would like," he said. "My suspicion is that there will still be a small chance that we could see a wave that is bigger than previously."
Prof Medley confirmed that the models for July 19 could still show a chance that the NHS will be overwhelmed by Covid admissions.
"I think, though, that we will likely be able to say that although there is that risk it may well be much smaller than we perceive it now," he added. "But it's an uncertain situation and we might, in three weeks time, be in a position where we say it is inevitable that it will happen."
Meanwhlie, Sir Simon also announced that around 1,000 diabetes patients will be given artificial pancreases so they do not have to inject insulin.
As part of a pilot scheme, patients with Type 1 diabetes will be able to use the devices which continuously measure a person's glucose levels and deliver insulin directly to the bloodstream, automatically balancing the patient's blood sugar levels. The devices could help eliminate finger prick tests and prevent life-threatening hypoglycaemic attacks.
Sir Simon said the technology was just "one example of a whole fizz of innovation which continues across the health service", adding: "Living with diabetes is a daily challenge for millions of people across England, and this closed loop technology has the potential to make a remarkable difference to their lives.
"In a year that marks a century since insulin was discovered – which revolutionised the world of diabetes – this innovation is a prime example of the NHS's continued progress in modern medicine and technology."