Study Design and population
This study has a cross-sectional design. We established a network of
pediatricians who volunteered to take part in the study and focused on
three areas/counties within Bavaria with very high, moderate and average
infection rates as indicated by positive PCR tests per 100,000
inhabitants according to the Robert Koch Institute, the German center
for disease prevention (figure 1). In areas where the number of willful
study participants exceeded the capacity of local pediatricians, a study
team supported sample collections. The sample collection took place in
the three study areas (Tirschenreuth; Regensburg city and county;
Oberbayern/ alpine region from May 22nd to July
22nd 2020 in a sliding window approach. Invitation to
participate for children age 1 to 14 years was based on two approaches:
(1) All children of that age group who were scheduled for a prevention
program visit in 2020 with the respective pediatrician were invited to
participate and (2) all children whose parents and the children
themselves wanted to participate voluntarily were also tested. In those
cases, also siblings older than 14 years were included into the study.
The study was approved by the Ethics Committee of the University of
Regensburg (file-number: 20-1865-101).