Funding for this research was provided by:
Received: 22 February 2021
Accepted: 30 April 2021
First Online: 17 May 2021
: All other authors declare that they have no conflict of interest.
: This research involved human participants. Every participant gave informed consent for this study. All the findings, data acquisition and processing in this study comply with the ethical standards laid down in the latest declaration of Helsinki. The study was approved by the local ethics committee of the University of Regensburg (EudraCT-Nummer 2009-012275-98).