Microscopic Lung Damage May Continue in 'Long COVID'
Get authentic, real-time news that helps you fight COVID-19 better.
Install PlexusMD App for doctors. It's free.
The persistent breathing issues that plague some COVID-19 survivors, known as "long COVID," may be due to microscopic processes that continue to damage lungs even after the acute infection is over, new findings suggest. Researchers studied blood and bronchoalveolar fluid samples from 38 patients who still had breathing problems at least three months after they were discharged from the hospital.

Compared to healthy volunteers, the airways of these COVID-19 survivors had higher numbers of cytotoxic lymphocytes (especially tissue-resident CD8+ T cells), lactate dehydrogenase, and albumin (biomarkers of cell death and barrier integrity).

"Interestingly, similar changes were not found when comparing blood samples, where the composition of immune cells and proteins was similar to those of the healthy controls," said James Harker of Imperial College London, co-author of a report published on medRxiv ahead of peer review.

The findings, which still need confirmation in larger studies, suggest some patients have ongoing disturbances in their immune cells and damage to cells that line the airways, even several months after their initial infection and discharge from hospital, Harker told. "In a small group of patients, we were able to show that the abnormalities may in fact resolve with more time," Harker said.