Received: 2 November 2020
Accepted: 18 May 2021
First Online: 31 May 2021
: The study was approved by the Vietnam National Children’s Hospital Committee under reference number NHP-RICH-16-20. All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethics Committee of Vietnam National Children’s Hospital and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. ritten informed consent was obtained from the parents of all individual participants included in this study.
: The authors have agreed to submit it in its current form for consideration for publication in the Journal.
: The authors declare that they have no competing interests.