Institutional Review Board Statement
The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the independent ethics committees in Germany (Ärztekammer Berlin; protocol version n. 1.1 approved on 11 January 2021), Bulgaria (Ethics Committee for Clinical Trials, Sofia; protocol version no. 1.1 approved on 26 Febrary 2021), Hungaria (ETT-KFEB, Budapest; protocol version no. 1.1 approved on 18 March 2021) and the local ethics committee of the Czech Republic (Etická komise Nemocnice, Strakonice) (protocol version no. 1.1 approved on 18 February 2021).