Younger adults admitted to hospital with Covid are almost as likely to suffer from complications as those over 50 years old, a study has found.
Four in 10 of those between 19 and 49 developed problems with their kidneys, lungs or other organs while treated.
The research looked at 73,197 adults of all ages across 302 UK hospitals in the first wave of Covid in 2020.
"The message is that this is not just a disease of the elderly and frail," said Prof Calum Semple, who led the work.
"The data reinforces the fact that Covid is not flu and we are seeing even young adults coming into hospital suffering significant complications, some of which will require furthering monitoring and potentially further treatment in the future."
The study, conducted by researchers at seven UK universities, the Department of Health and Social Care and Public Health England, looked at the number of "complications" in those needing hospital treatment for Covid-19, defined as an organ-specific medical diagnosis.
Overall, around half of all adult patients suffered a least one complication during their hospital stay. The most common was a kidney injury, followed by lung and heart damage.
The highest rates were in those over 50 years old, with 51% reporting at least one problem. But they were also "very common" in younger age groups. Some 37% of 30 to 39 year olds and 44% of 40 to 49 year olds had at least one complication recorded by nurses and medical students involved in the study.
Doctors are not yet certain how a severe Covid illness can cause organ damage, but it is thought in some cases the body's own immune system can spark an inflammatory response and injure healthy tissue.
Paul Godfrey, from Frinton in Essex, developed Covid in March 2020 after suffering what he thought was a chest infection.
Paul, who was 31 at the time of diagnosis and has the lung condition bronchiectasis, said: "There's no doubt about it - the NHS staff who cared for me saved my life. I would not be here today if it wasn't for them."
The study, published in the medical journal the Lancet, found that those with pre-existing conditions were more likely to report complications but the risk was high even in young, previously healthy individuals.
'Worst experience of my life'
Paul was diagnosed with pneumonia in Colchester hospital and was told the bottom half of both his lungs had collapsed. He narrowly avoided being placed in an induced coma and spent two weeks on a Covid ward before he was allowed home in a wheelchair.
The research showed that 13% of 19 to 29 year olds and 17% of 30 to 39 year olds hospitalised with Covid were unable to look after themselves at discharge and had to rely on friends and family.
"It was the worst experience of my life and I am still dealing with it 18 months later," said Paul, who continues to suffer from extreme fatigue and breathlessness caused by his illness.
"I don't really know what the damage is to my body so I am just praying I get back to what I was."
Covid and younger adults
Age is the single largest factor in determining a severe Covid infection.
Of the 406,687 people taken to hospital with the disease in England since the start of the pandemic, 62% were over the age of 65.
That leaves another 155,866 under the age of 65 who have needed hospital treatment since February 2020.
Higher vaccination rates in the elderly and vulnerable population mean that the average age of those hospitalised with the disease has been falling.
In the week ending 4 July, there were just 17 people over 85 years old admitted to hospital with Covid in England, compared with 478 aged between 25 and 44.
The research was conducted in the first wave of the pandemic between 17 January and 4 August 2020 - before vaccines were available and new variants of the virus had been detected.
The authors said the data suggested those with more severe Covid symptoms at admission to hospital were more likely to suffer serious health problems, showing the importance of vaccines in reducing the severity of the disease in this latest wave.
The study was only designed to look at short-term complications during a hospital stay but there is evidence some organ damage can persist, becoming a form of what is known as long Covid.
"We do know from other infectious diseases that these sorts of problems with your kidneys or heart can develop into longer-term complications," said Dr Annemarie Docherty, senior clinical lecturer at the University of Edinburgh and a consultant in intensive care medicine.
"I think it's reasonable to expect that this may be the same with Covid-19."
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