Long-lasting immune activity in the airways might be the cause of persistent breathlessness following COVID-19, according to new research.

This is according to a new study of 38 people who were previously hospitalised with severe COVID-19.

The results, published in Immunity, suggest these patients have an altered landscape of immune cells in their airways and signs of ongoing lung damage. However, the preliminary results hint that this might improve over time.

The researchers say that their findings need to be confirmed by a larger study, but suggest that recovery from COVID-19 might be accelerated by treatments that dampen the immune system and reduce inflammation.

Joint lead author, Dr James Harker, from Imperial’s National Heart & Lung Institute, said: «Our study found that many months after SARS-CoV-2 infection, there were still abnormal immune cells in the airways of patients with persistent breathlessness. We also identified a protein ‘signature’ in the lungs indicating ongoing injury to the airways.»

Joint senior author, Professor Pallav Shah, also from Imperial’s National Heart & Lung Institute, said: «These findings suggest that persistent breathlessness in our group of COVID-19 patients is being caused by failure to turn off the immune response, which leads to airway inflammation and injury. The next steps of our research will be to see if there are treatments that can reduce the immune activity and whether they help to reduce the persistent breathlessness some patients experience.»

Previous studies have examined the causes of post-COVID-19 breathlessness by looking at markers in the blood, but the new study looks directly at which immune cells are active in the lungs too.

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Materials provided by Imperial College London. Original written by Emily Head. Note: Content may be edited for style and length.