Chronic Pulmonary Complications After COVID-19: An Observational Study of Postinfection Lung Changes Over 2 Years

Long-term pulmonary complications after COVID-19 are increasingly recognized, but few studies have characterized their progression and risk factors over extended follow-up.

What are the prevalence, progression, and predictors of chronic pulmonary complications in COVID-19 survivors over a 24-month period?

We conducted a prospective observational cohort study of 355 adults (20-55 years of age) with polymerase chain reaction-confirmed COVID-19 in Egypt, followed at 6, 12, and 24 months after infection. Assessments included pulmonary function tests, high-resolution CT scan, and standardized symptom questionnaires. Multivariable logistic regression was used to identify independent predictors of interstitial fibrosis and pulmonary embolism (PE).

Chronic cough prevalence decreased from 45% at 6 months to 7% at 24 months (P < .001). Asthma-like symptoms declined from 30% to 15% (P = .002). Conversely, PE prevalence increased from 10% to 19% (P = .014), and interstitial fibrosis rose from 3% to 25% (P < .001). Patients with severe acute COVID-19 had lower diffusing capacity for carbon monoxide throughout follow-up (mean difference, -12.8%; P = .002). Independent predictors of PE at 24 months included age (OR, 1.05 per year; 95% CI, 1.02-1.08), unvaccinated status (OR, 2.3; 95% CI, 1.4-3.9), and comorbidities (OR, 1.8; 95% CI, 1.1-3.1). Vaccinated participants had significantly lower rates of fibrosis (12% vs 28%, P < .01) and PE (10% vs 22%, P = .001), and more rapid symptom resolution.

Most COVID-19 survivors experienced symptomatic and functional improvement over 2 years. However, a substantial subset, particularly those unvaccinated or with severe initial illness, developed progressive interstitial fibrosis and increased risk of PE. Long-term pulmonary surveillance and vaccination may reduce these chronic sequelae.