Received: 14 December 2020
Accepted: 7 April 2021
First Online: 21 April 2021
: This study was approved by The Ethics Committee of The National Institute of Children’s Diseases (NICD), Bratislava, Slovakia. The study was performed in the accordance with the Declaration of Helsinki. Written informed consent was obtained from legal guardians of all participants.
: Not applicable.
: The authors declare that they have no competing interest.