On July 1, Columbia University’s Christine Kim Garcia published a paper in the Ann Am Thorac Soc regarding post-COVID sequelae titled “Imaging, Pulmonary Function, and Histopathologic Findings of Persistent Fibrosis in a Longitudinal Cohort 3-Years after COVID-19.” This study systematically reveals the long-term evolution of pulmonary fibrosis caused by the coronavirus through a three-year follow-up of 102 severe COVID-19 survivors.
This prospective longitudinal study shows that 61% of severe patients still exhibit pulmonary fibrosis-like changes three years after infection, primarily characterized by reticular opacities and traction bronchiectasis. Comparisons of CT imaging at three time points—4 months, 15 months, and 3 years—indicate that while there is a slight trend of improvement (with 9% of patients showing improvement), the vast majority of patients (91%) maintain stable fibrosis without any cases of deterioration. Notably, these structural changes are significantly associated with pulmonary function impairment—patients with fibrosis changes demonstrate lower diffusion capacity and shorter 6-minute walk distances.
The research team identified several risk factors through multivariable analysis: male gender, lower BMI, shorter leukocyte telomere length, more severe underlying conditions, and a history of mechanical ventilation were positively correlated with the occurrence of fibrosis, while Black ethnicity showed a protective effect. Particularly noteworthy is that the study first confirmed through bronchial biopsy that these long-term fibrosis changes are primarily characterized histopathologically by small airway lesions and focal interstitial thickening, rather than widespread pulmonary fibrosis, which explains why patients experience expiratory air trapping.
Despite the relatively stable imaging findings, the correlation between these persistent structural changes and functional impairment suggests that severe COVID-19 may lead to irreversible lung damage. The findings of the paper emphasize the necessity of establishing long-term follow-up mechanisms, especially for severe patients requiring mechanical ventilation.
As the longest follow-up study on pulmonary sequelae of COVID-19 to date, this result provides important clues for understanding the pathogenesis of long COVID. The researchers recommend that clinicians conduct regular pulmonary function monitoring for severe recovery patients for at least 3 years, particularly focusing on the assessment of diffusion capacity and small airway lesions. The propensity score balancing method used in the study also sets a new methodological standard for such long-term observational research.