Papers released by the governments Scientific Advisory Group for Emergencies (Sage) also revealed half of patients in hospital with the virus suffered complications, with one in four struggling when they got back home.
Younger patients under the age of 50 were more likely to suffer complications.
The reports present the first substantial evidence that Covid could be the cause of significant long term ill-health, with the virus attacking the body’s organs and causing diseases of the liver, heart, lungs and kidneys.
Last week The Independent revealed widespread concerns that the UK’s already stretched community health services would be unable to cope with the expected rise in patients needing home nursing care, as well as therapy to learn to walk and talk again, after weeks and months unconscious in intensive care.
One study looking at 47,780 coronavirus patients who were discharged alive by the end of August last year found 30 per cent of patients, 14,000, were readmitted to hospital within 140 days while 12 per cent, 5,875, died.
These results were substantially higher than a control group of similar patients which saw deaths in under 2 per cent of patients and less than 10 per cent needing to be readmitted.
The paper said Covid patients suffered multi-organ problems including elevated rates of diabetes, kidney and liver disease as well as major cardiac disease events such as heart attacks or strokes.
The paper said it did not prove a causal relationship between Covid-19 and the post-discharge problems, but warned there was a statistical correlation that needed investigating.
A second piece of research, considered by Sage on 4 February, looked at more than 73,000 adults admitted with Covid to 300 hospital settings across the UK between January and August last year.
It found half of all the patients had at least one complication with complications, such as heart, kidney or lung problems, most common in men aged 30 and over.
Of those patients who were discharged, one in four had problems coping at home.
The study warned: “Complications and worse functional outcomes in patients admitted to hospital with Covid-19 are high, even in young, previously healthy individuals.
“Covid-19 complications are likely to cause significant strain on health and social care in the coming years.”
It concluded: “Many of the complications identified are likely to have important long-term effects. Healthcare systems and policy makers should plan for increases in population morbidity arising from Covid-19 and its subsequent complications. As complications following Covid-19 are common across all age groups and comorbidities, public health messaging around the risk Covid-19 poses to younger otherwise healthy people should be considered alongside vaccine prioritisation.”
Peter Openshaw, professor of experimental medicine at Imperial College London and one of the co-authors of the study, said: “Most planning with respect to Covid has focused on mortality, for example in setting the priority groups for vaccination.
“We now show that there are other severe outcomes that need to be taken into account in estimating the impact of Covid-19; long-term complications are especially common in males, those aged 30 and over and in patients with comorbidities.”
A third paper considered by Sage estimated there were more than 300,000 people by the end of December reporting symptoms of coronavirus that had lasted for up to 12 weeks. The numbers may have grown since then as the peak of the second wave did not occur until January.
Examples of ‘long covid’ symptoms included fatigue, coughing, headaches, and muscle pains but the study did not consider all symptoms.
Charles Bangham, professor of immunology at Imperial College London, said there could be up 50 symptoms of long Covid with some surveys finding as many as 100.
He said: “It is now clear that beating an initial infection from this virus is not the end of the story. For a significant proportion of people, Covid-19 is turning out to be a long-term illness.
“With more than 100 million Covid-19 cases worldwide, the health burden left by long Covid could be enormous. In the UK alone, there could be hundreds of thousands of patients who endure symptoms for many months, putting further pressure on an already stretched healthcare service.
“This will not only impact the lives of those who are suffering, but also has the potential to create an ongoing economic burden if they find themselves unable to work.