Funding for this research was provided by:
Sächsisches Staatsministerium für Soziales und Verbraucherschutz
Received: 11 March 2019
Accepted: 22 August 2019
First Online: 29 August 2019
Ethics approval and consent to participate
: This study was approved by the Research Ethics Committee of TU Dresden.
: Both legal guardians and children signed informed consent in a form approved by the Research Ethics Committee of the TU Dresden.
: The authors declare that they have no competing interests.