Received: 20 March 2020
Accepted: 12 July 2020
First Online: 31 July 2020
Ethics approval and consent to participate
: The study was approved by the Ethics Committees of Capital Institute of Pediatrics (SHERLL 2015009) and the informed consent was provided for ethical review. The written informed consent of each participant was obtained from a parent or guardian.
: Not applicable.
: The authors declare that they have no competing interests.