Results
In total, 40 children fulfilled the inclusion criteria between January and June 2021. One boy was excluded due to positive paired serology forMycoplasma pneumoniae . In 39 children (median age 13.5 ± 4.8 years, IQR: 8-15 years, boys 43.6%), COVID-19 was confirmed by positive PCR test in 35 (89.7%) and by serology in 14 (35.9%). Exertional dyspnea (76.9%) followed by chronic cough (48.7%) represented dominant symptoms, while dyspnea at rest and chest pain were less prevalent (30.8% resp. 17.9%) (see Table 1). Half of the children (53.8%) reported more than one symptom. Single abnormal results of lung function tests, chest X-ray, or D-dimers were seen in 15 children (38.5%), in 3 children (7.7%) we found a combination of two pathological results. There was no association between any symptoms and abnormal results. In 9 subjects, we suspected incipient bronchial asthma coinciding with COVID-19 infection based on personal and family histories, spirometry, laboratory results, and therapeutic effect of anti-asthma treatment. After data collection, we recognized four strikingly different subgroups of post-COVID manifestation in children: “standard”, “asthmatic”, “sporty” and “polymorphous”. In subgroup of 5 “sporty” children with high-intensity training, no dyspnea at rest was noticed, and we saw physiological results of all diagnostic tests except for 1 abnormal chest X-ray. In other five children who suffered from various “polymorphous” symptoms, we observed a trend to higher prevalence of dyspnea at rest and/or fatigue compared to other participants (Fisher’s exact test p=0.056).
In 34/39 subjects followed for the whole duration of our study (1 lost from follow-up, 4 with current follow-up <6 months), complete remission of tracked symptoms occurred within a median of 4 months (range 1.5-8, see Table 2.). We observed two unusual courses of the disease in our group. A 15-year-old boy with pleural pain, pleural effusion confirmed by lung ultrasound, normal ventilation/perfusion lung scan and normal D-dimers, and complete remission within seven months after first post-COVID symptoms. An 18-year-old girl with hemoptysis during acute COVID had abnormal 6MWT, physiologic chest CT scan, and D-dimers and complete remission within six months (Table 3).
Table 1 Symptoms and abnormal results in all subjects and post-COVID subgroups