A study involving 384 patients found 69 per cent still experienced fatigue 54 days after discharge, while 53 per cent suffered from persistent breathlessness.
Some 34 per cent still had a cough and 15 per cent reported depression.
In addition, 38 per cent of chest radiographs (X-rays) remained abnormal while nine per cent were getting worse.
The study was carried out by researchers from the University College London (UCL) division of medicine in collaboration with clinicians at the Royal Free London (RFL) and University College London Hospitals NHS Trust (UCLH).
The patients had been treated at Barnet Hospital, the Royal Free or UCLH. The average length of stay in hospital was 6.5 days.
Dr Swapna Mandal, an honorary clinical associate professor at UCL division of medicine, said the data shows so-called "long Covid" is a real phenomenon and that more research is needed to understand how Covid-19 symptoms can be treated in the long term.
She said: "Patients whose Covid-19 illness is serious enough for them to require hospital care often continue to suffer significant symptoms for many weeks after their discharge."
Professor John Hurst at UCL division of medicine, added: "Understanding 'long Covid' is critical in helping people who have been through this life-changing experience return to health.”
The study, published in medical journal Thorax, saw clinical teams set up a post-Covid follow up clinic to review the psychological and physiological symptoms of discharged patients.
All of the patients were called or seen in person by a member of the clinical team an average of 54 days after they left hospital.
For patients whose chest X-ray was still showing signs of infection when they were discharged, 62 per cent had a normal X-ray when it was repeated. The remainder were still showing changes.
Almost one in 10 (9 per cent) of these patients had an X-ray that was worse than when they were discharged, researchers found.
The scientists note a number of limitations to the study, including that it only included patients who tested positive for SARS-CoV-2, the virus that causes Covid-19, and that patients requiring prolonged ICU and in-patient stay may be under-represented in the analysis.
They add that not all participants were willing to take part in the review or attend for investigations which potentially introduced selection bias.
The researchers cannot determine if these features are unique to Covid-19. They may simply be similar to those following admission for other critical respiratory illnesses.
Additional reporting by PA
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