A Sage expert has warned that younger Covid patients are suffering from kidney and lung damage.
Calum Semple, a child health and outbreak medicine professor at the University of Liverpool, said nearly all of the people currently in hospital are unvaccinated.
He added that otherwise healthy Brits could end up with lung scarring and kidney disease after catching coronavirus.
It comes as Boris Johnson prepares to lift almost all Covid restrictions on July 19, meaning an end to social distancing and masks.
Speaking about the younger Covid patients currently in hospital, Professor Semple said: "What's surprising is that although they're not dying, they are suffering quite a lot of injuries, so we're seeing a lot of kidney injuries and lung injuries in these younger people.
"So my concern now is not so much about death, although every death is a tragedy.
"My concern now is about otherwise healthy people that would normally be economically important and working and going about their daily lives, they're going to get damaged.
"They're going to get lung scarring and kidney disease... this is actually different to long Covid, this is acute Covid injury."
Professor Semple told BBC Breakfast he noticed hints in Monday's Downing Street press conference that some restrictions could return in the winter.
He said "the language was subtly different - rather than being totally reversible, there was a few caveats being thrown in there, suggesting that come winter time some measures may have to come back."
The expert added that he would continue to wear a face mask "particularly in enclosed areas".
Professor Semple also said that if people proceed cautiously "we probably won't see" some of the numbers suggested in "reasonable worst case scenarios", such as 200 deaths per day or 100,000 cases per day.
It comes as coronavirus deaths in England and Wales remain low despite soaring cases, according to new data.
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A further 109 Covid deaths have been recorded across England and Wales between June 26 and July 2, the ONS said.
Although this is a slight increase on the week before, it is still a low figure when compared to the sharp spike in cases.
Over the same period more than 150,000 new Covid infections were recorded across the UK.
ONS data showed that the number of deaths recorded in the latest week in England and Wales was actually lower than the five-year average.
The new figures come less than a week before Boris Johnson drops almost all coronavirus restrictions on July 19.
This "big bang" approach will mean an end to compulsory face masks and social distancing.
The Prime Minister insists he is following the science, and hopes lifting restrictions on this date will stop us having to open up just as cases are surging into winter.
