Results
1 .Demographic and clinical characterization of the study groups
Our study group comprised 17 convalescent COVID-19 children with PASC manifestation (further referred as PASC) and 13 convalescent COVID-19 children without PASC manifestation (further referred as control). All study participants had a negative SARS-CoV-2 nasal swab tested via RT-PCR on recruitment. During the acute phase of COVID-19 disease 100% of both study groups presented moderate/asymptomatic COVID-19 disease severity without need for hospitalization. The median COVID-19 convalescence time was 5 and 3 months for the PASC and the control study group respectively (PASC range 2-11 months, control 2-8 months) (unpaired t test PASC vs control p=0.89). All children participated did not receive a COVID-19 vaccine. The median age of PASC study group was 11 years (range 3-18 years) and of the control cohort 12 years (range 6-15 years) (unpaired t test PASC vs control p=0.39). The PASC and control cohorts comprised of 53% (n=9) and 15% (n=2) female participants, respectively and showed no significant gender difference (Fisher´s exact test, p=0.0575). The demographic characteristics of the study cohorts are presented in Table 1.
The most common PASC symptoms among the PASC study group were shortness of breath/exercise intolerance and paresthesia with 71% (n=12) and 59% (n=59) respectively, while smell/taste disturbance, chest pain, dyspnea, headache and concentration disturbance were also quite common (29 to 41% of the PASC study cohort) (table 2). The blood count (hemoglobin, leukocytes & thrombocytes) and the clinical chemistry (AST/GOT, GPT/ALP, γ-GT, creatinine, D-dimers, CRP) excluding CK showed no statistical differences among the study groups (table 2). However, the control study group showed significantly higher CK-levels compared to PASC subjects (p=0.011, Mann Whitney Test) (median 153, range 113-253, normal<170U/l). This result may reflect more intense physical/athletic activity among the control study group due to the absence of PASC symptomatic.