Received: 11 November 2019
Accepted: 22 April 2020
First Online: 29 April 2020
Ethics approval and consent to participate
: The Ethical Committee of the Medical University of Lublin approved the study protocol (No. KE-0254/75/211). From all children’s parents, written informed consent was obtained.
: Not applicable.
: The authors declare that they have no competing interests.