Acknowledgements
Open Access funding provided by Projekt DEAL. This work was in part supported by a COVID-19 grant from the state Baden-Württemberg.

Authors’ contributions
Conceptualization: all authors; methodology, formal analysis, and investigation: Samir Abu-Rumeileh, Ahmed Abdelhak, and Matteo Foschi; writing—original draft preparation: all authors; figure preparation: Matteo Foschi; writing—review and editing: all authors; supervision: Markus Otto and Hayrettin Tumani.

Compliance with ethical standards

Conflicts of interest
The authors declare that they have no conflict of interest related to the content of this article.

Ethical standard
For the present study, no authorization to an Ethics Committee was asked, because the original reports, nor this work, provided any personal information of the patients.