The long-term effects of Covid-19 are now well-recognized in patients who have recovered from the infection. As per the Centers for Disease Control and Prevention (CDC), post-Covid conditions are a wide range of new, returning, or ongoing health problems people can experience 4 weeks after being infected with Covid-19. These post-Covid conditions are also known as long Covid, long-haul Covid, post-acute Covid-19, chronic Covid or Post-Acute Sequelae of SARS-CoV-2 infection (PASC). 

A recent study published in The Lancet Respiratory Medicine has added to the growing body of evidence for long-Covid. The study, which tracked patients with severe Covid-19 pneumonia up to one year after hospitalization, has shown that while dyspnea and exercise capacity improved in most patients, some continued to show evidence of physiological and radiographic changes.

The study prospectively analysed outcomes in 83 patients with severe Covid-19 pneumonia, who needed hospitalization but no mechanical ventilation. They were followed-up at 3 months, 6 months, 9 months and 12 months after discharge from Renmin Hospital of Wuhan University, Wuhan, China. All patients were non-smokers and had no history of any chronic disease such as hypertension, diabetes, cardiovascular diseases, cancer, asthma, or COPD. Patients also underwent serial pulmonary function tests (PFTs), 6-min walk test (6MWT) and HRCT chest, in addition to routine evaluation during each follow-up visit.

The results showed that at 12 months after discharge, one-third of patients still had residual abnormalities of lung function. The most common finding was a reduction in gas transfer as measured by diffusing capacity of the lungs for carbon monoxide (DLCO). Low DLCO was more frequently found in female patients vis-à-vis male patients.

Also, 24% of patients continued to show radiological changes at 12 months after discharge. These changes included findings potentially consistent with evolving fibrosis in some patients with the presence of interstitial thickening and reticular opacity on HRCT. But, neither definitive fibrosis nor progressive interstitial changes were evident. 

A progressive increase in distance on 6MWT was also noted, 535 m at 3 months to 585 m at 6 months; it increased further at 9 and 12 months indicative of improved exercise capacity. 

The study draws attention to the high burden of lung fibrosis after Covid-19 recovery, which could be potentially substantial, given the huge number of people infected with SARS-CoV-2. It highlights the fact that routine respiratory follow-up of patients with Covid-19 pneumonia is required, after they are discharged from the hospital.

(Source: Wu X, et al. 3-month, 6-month, 9-month, and 12-month respiratory outcomes in patients following COVID-19-related hospitalisation: a prospective study. Lancet Respir Med. 2021 Jul;9(7):747-754)