Abstract
COVID-19 is caused by coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). In a striking contrast to adults, children usually suffer mild, or even no symptoms of the COVID-19 disease.
This likely results in underestimation of the overall incidence and prevalence of COVID-19 in paediatric population. A more accurate tool to determine the prevalence of COVID-19 is testing for specific anti-SARS-CoV-2 antibodies.
In Thomayer University Hospital in Prague, we screened 200 children aged 0-18 years for the presence of anti-SARS-CoV-2 antibodies in two separate phases, in 2020 and a year later in 2021. The results showed that by autumn 2021 at least 30% of the children had contracted SARS-CoV-2 infection, which is double the confirmed cumulative number of childhood infections, 30% of whom experienced no symptoms.
The antibodies values negatively correlated with time from infection and were significantly lower in children over 12 years of age. 84% of seropositive children tested positive for virus-specific T lymphocyte-mediated immune response, confirming the post-infection establishment of cellular immune memory. The positivity was detectable as long as 12 months after infection and did not correlate with anti-SARS-CoV-2 antibodies titres or age.