Ethical Considerations
This study was granted ethical approval from the ethics committee of the Federal Institute for Occupational Safety and Health in Germany (032_2019_Michel). Owing to several restrictions (eg, high degree of uncertainty as to whether we would be able to conduct the study as planned due to COVID-19 restrictions), we were unable to prepare a properly detailed protocol for a preregistration. However, we registered the study retrospectively after it ended in the German Clinical Trials Register (registration number: DRKS00032721).