Children were less frequently infected with SARS-CoV-2 than adults during 2020 COVID-19 pandemic in Warsaw, Poland.

Clinical data suggest that during the current COVID-19 pandemic, children are less prone than adults to SARS-CoV-2 infection. Our purpose was to determine the frequency of SARS-CoV-2 in children vs. adults during the 2020 pandemic in Warsaw, Poland, and to investigate whether RSV and/or influenza A/B infections were associated with SARS-CoV-2 infections. We present results of RT-PCR tests for SARS-CoV-2 performed in Warsaw, Poland. Some of the pediatric subjects were also PCR-tested for RSV, and A and B influenza. We compared the test results from the four groups of symptomatic and asymptomatic subjects: 459 symptomatic pediatric patients (children 0-18 years old), 1774 symptomatic adults, 445 asymptomatic children, and 239 asymptomatic adults. 3.26% (15/459) of symptomatic pediatric patients were positive for SARS-CoV-2 in contrast to 5.58% (99/1774) of symptomatic adults (p = 0.0448). There were no SARS-CoV-2 positive cases in the group of asymptomatic children (0/445) and two positive cases in the group of asymptomatic adults (2/239), i.e., 0.83%. In the group of symptomatic pediatric patients, 17.14% (6/35) (p = 0.0002) were positive for RSV, 8.16% (4/49) were positive for influenza A, and 2.04% (1/49), thus 10.20% (5/49) (p = 0.0176) for influenza A/B. Children were less prone to SARS-CoV-2 infection than the adults during the COVID-19 pandemic in Warsaw. Higher percentage of symptomatic children was infected with RSV or influenza A/B than with SARS-CoV-2. This suggests a necessity for the testing for all these viruses for an early identification and isolation of SARS-CoV-2-positive patients for an ensuing 2020 autumn return of COVID-19.