Background: Children and youth are affected rather mildly in the acute phase of COVID-19 and thus, SARS-CoV-2 infection infection may easily be overlooked. In the light of current discussions on the vaccinations of children it seems necessary to better identify children who are immune against SARS-CoV-2 due to a previous infection and to better understand COVID-19 related immune reactions in children. Methods: In a cross-sectional design, children aged 1–17 were recruited through primary care pediatricians for the study (a) randomly, if they had an appointment for a regular health check-up or (b) if parents and children volunteered and actively wanted to participate in the study. Symptoms were recorded and two antibody tests were performed in parallel directed against S (in house test) and N (Roche Elecsys) viral proteins. In children with antibody response in either test, neutralization activity was determined. Results: We identified antibodies against SARS-CoV-2 in 162 of 2,832 eligible children (5.7%) between end of May and end of July 2020 in three, in part strongly affected regions of Bavaria in the first wave of the pandemic. Approximately 60% of antibody positive children ( n = 97) showed high levels (>97th percentile) of antibodies against N-protein, and for the S-protein, similar results were found. Sufficient neutralizing activity was detected for only 135 antibody positive children (86%), irrespective of age and sex. Initial COVID-19 symptoms were unspecific in children except for the loss of smell and taste and unrelated to antibody responses or neutralization capacity. Approximately 30% of PCR positive children did not show seroconversion in our small subsample in which PCR tests were performed. Conclusions: Symptoms of SARS-CoV-2 infections are unspecific in children and antibody responses show a dichotomous structure with strong responses in many and no detectable antibodies in PCR positive children and missing neutralization activity in a relevant proportion of the young population.
【저자키워드】 COVID-19, SARS-CoV-2, antibody, children, Neutralizing, 【초록키워드】 primary care, vaccination, pandemic, SARS-COV-2 infection, Antibody Response, Infection, Viral proteins, immune, Neutralizing activity, Region, Health, Seroconversion, response, Antibody test, PCR test, Roche, First wave, S-protein, neutralization capacity, COVID-19 symptom, cross-sectional design, Loss of Smell, acute phase, PCR positive, neutralization activity, parent, positive, N-protein, Elecsys, immune reaction, Randomly, identify, performed, affected, proportion, recruited, detectable, was determined, age and sex, were recorded, eligible, 【제목키워드】 Capacity,