Tens of thousands of people will need to be recalled to hospital after a serious Covid-19 infection to check if they have been left with permanent lung damage, doctors have told the BBC.
Experts are concerned a significant proportion could be left with lung scarring, known as pulmonary fibrosis.
The condition is irreversible and symptoms can include severe shortness of breath, coughing and fatigue.
NHS England said it was opening specialist rehabilitation centres.
Retired taxi driver Anthony McHugh, 68, was admitted to hospital on 6 March with coronavirus symptoms.
His condition deteriorated and he was transferred to intensive care and placed on a ventilator for 13 days.
“I was feeling breathless, then I just remember being rushed into ICU, and after that it was all just a blank,” he said.
‘Lucky to be alive’
Mr McHugh, from Hertfordshire, spent a total of four weeks in hospital and another two in an NHS rehabilitation unit. He returned home in mid-April but still suffers from breathing difficulties two months later.
“It’s little things like walking up the stairs or watering the flowers outside. I start bending down and I have to stop,” he said.
CT scans taken while he was in hospital showed a white mist, or “ground glass”, pattern in both lungs – a characteristic sign of coronavirus
In serious cases it’s thought coronavirus can trigger an exaggerated immune response causing mucus, fluid and other cells to fill the air sacs, or alveoli. When this happens, pneumonia can set in, making it difficult to breathe without assistance.
An X-ray of Mr McHugh’s lungs taken six weeks after he left hospital showed thin white lines, known as reticular shadowing, that could indicate the early signs of scarring or pulmonary fibrosis.
‘That’s a worry’
“With all these cases, we can’t say for certain at the moment,” said Dr Sam Hare, an executive committee member of the British Society of Thoracic Imaging and advisor to the Royal College of Radiologists.
“But usually with a virus or infection at six weeks, you would expect the scan to have returned to normal. It hasn’t and that’s the worry.”
Like other Covid-19 patients who have been discharged from hospital, Mr McHugh will need another scan at 12 weeks to see if the suspected scarring on his lungs has deteriorated.