Assessment of Pulmonary Function in Children with Post-Acute Sequelae of COVID (PASC) Using Impulse Oscillometry and the Role of Vaccination

Background: Post-acute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID syndrome (LCS), is characterized by persistent symptoms following SARS-CoV-2 infection and poses significant health challenges, particularly impactingpulmonary function in children. This study aims to evaluate the effect of COVID-19 vaccination on pulmonary function in children with PASC using standardized spirometry and impulse oscillometry (IOS). Methods: This prospective, observational study was conducted from July to September 2022, at the tertiary medical center of children’s hospital in central Taiwan. Pediatric patients aged 6 to 18 years diagnosed with PASC were enrolled. Demographic data, vaccination status, and blood test results were collected. Pulmonary function was assessed using spirometry and IOS, measuring parameters such as respiratory resistance (R5, R20) and reactance (X5). Statistical analyses explored the association between IOS results and clinical symptoms, as well as vaccination status. Results: Among 209 children, 78.7% were vaccinated. IOS detected abnormalities in 74.6%, with 12.0% diagnosed with obstructive lung disease (OLD) and 62.9% with small airway disease (SAD). Fatigue (56.0%) and dyspnea (52.0%) were most common in OLD, while chest pain (45.0%) and cough (41.7%) prevailed in SAD. Vaccinated children showed significantly lower respiratory resistance (R5, R20, p<0.01) and improved reactance (X5, p<0.001). Vaccination did not significantly reduce respiratory-related symptoms but was associated with lower risks of decreased appetite (OR=0.399) and sleep disturbance (OR=0.345). Conclusion: COVID-19 vaccination may have a protective effect on pulmonary function in children with PASC, highlighting it’s in mitigating long-term respiratory complications. Further studies are needed to explore underlying mechanisms.