London, March 30 : Some people recovering from Covid-19 pneumonia have CT evidence of damage to their lungs that persists a full year after the onset of symptoms, according to a study. Covid's short-term effects on the lungs, such as pneumonia, are well documented. Much less is known about the illness' long-term effects on the lungs. As part of an Austria-based observational study on the development of lung disease in patients with SARS-CoV-2 infection, in the study, published in the journal Radiology, researchers looked at patterns and rates of improvement of chest CT abnormalities in patients one year after Covid pneumonia. CT has been an important imaging tool in the workup of patients suspected of having Covid. The researchers assessed lung abnormalities on chest CT in 91 participants, mean age 59 years, at several points over one year after the onset of Covid symptoms. At one year, CT abnormalities were present in 49, or 54 per cent, of the 91 participants. Of these 49 participants, two (4 per cent) had received outpatient treatment only, while 25 (51 per cent) were treated on a general hospital ward and 22 (45 per cent) had received intensive care unit (ICU) treatment. "The observed chest CT abnormalities from our study are indicative of damaged lung tissue," said Anna Luger, from the Department of Radiology at Innsbruck Medical University in Innsbruck, Austria. "However, it is currently unclear if they represent persistent scarring, and whether they regress over time or lead to pulmonary fibrosis," Luger added. While CT abnormalities decreased in initial follow-ups, 63 per cent of participants with abnormalities did not show any further improvement after six months. Age over 60 years, critical Covid severity and male gender were associated with persistent CT abnormalities at one year. Evidence from the SARS-CoV-1 outbreak of 2002 to 2004 shows that lung abnormalities may remain detectable even after decades, but do not show any progression, according to study co-author Leonhard Gruber, from the University. Recent studies, though, have shown a risk of progression of lung abnormalities such as the ones depicted on CT. The study underscores radiology's role in helping identify patients at risk for post-Covid consequences and assisting in Covid follow-up management. The researchers stated that long-term follow-up, both clinical and radiological, is necessary to gather more information about the course and clinical role of persisting SARS-CoV-2 related chest CT abnormalities. /IANS