Funding for this research was provided by:
Bundesministerium für Gesundheit (01EH0201)
Bundesministerium für Bildung und Forschung (01EH0201)
Received: 22 November 2018
Accepted: 5 November 2019
First Online: 3 December 2019
Ethics approval and consent to participate
: Written informed consent was obtained from all parents and from participants aged 14 years and older. The study was approved by the Ethics Committee at the Charité-Universitätsmedizin Berlin, Germany.
: Not applicable.
: The authors declare that they have no competing interests.