Primary outcomes
Of 672 children who met the inclusion criteria, 392 were disqualified based on the exclusion criteria. All the eligible children were approached but only 56 were consent to participate in the study. The average time of assessment after COVID-19 infection was 98.6±26.6 days. Twenty-one patients (37.5%) had respiratory sequalae with 11 patients (19.6%) having only prolonged respiratory symptoms, seven patients (12.5%) having only abnormal pulmonary function and three patients (5.4%) having both. The respiratory sequalae were present in 66.7% of patients who had non-severe disease and 33.3% with pneumonia. There was no significant relationship between the presence of any post COVID-19 symptoms and the presence of pulmonary function impairments (p -value = 0.69).
Table 1 presents the characteristics of patients and the two groups categorized by the presence of respiratory sequelae (post COVID-19 symptoms and/or pulmonary function impairment defined by abnormal spirometry). The average age of patients was 10.7±2.5 years. No significant difference was found in the baseline characteristics between the two groups, except FEV1 z-score that was significantly higher in patients without respiratory sequalae (0.88±1.11 vs -0.06±1.18, p -value = 0.003).
Regarding the history of acute COVID-19 infection, the most common symptoms were cough (62.5%), fever (62.5%), and rhinitis (50%). Forty-three patients (76.8%) had only upper respiratory symptoms, (mild COVID-19 infection) and 13 patients (23.2%) had pneumonia (moderate COVID-19 infection). After COVID-19 infection, 14 patients (25%) continued to experience post COVID symptoms. Among those with post COVID-19, fatigue was the most common (35%), followed by dyspnea and cough (28% each). Rhinorrhea was the least common symptom (14%).
Abnormal spirometry was observed in 10 patients (19.6%), accounting for approximately half of the patients with respiratory sequelae. Regarding the classification of pulmonary function impairment, seven patients (70%) had either low FEV1 or FEV1/FVC, i.e. obstructive impairment, and three of them responded to bronchodilator. Three patients (30%) had low FVC, i.e. possible restrictive impairment.
The proportion of history of COVID-19 pneumonia was higher in patients with respiratory sequalae than those without, but there was no statistical significance (33.3% vs 17.1%, p -value = 0.20). Seven of the patients with COVID-19 pneumonia (53.8%) had at least one post COVID symptoms, compared with seven of the patients with mild COVID-19 (16.2%). Two of the patients with COVID-19 pneumonia (15.3%) had pulmonary function impairment, compared with nine of the patients with mild COVID-19 infection (20.9%).