Received: 29 September 2019
Accepted: 4 March 2020
First Online: 20 March 2020
Ethics approval and consent to participate
: All the participants were given an explanation about the purposes of this study and their right to withdraw without any consequences. Written informed consent was obtained from all individual participants included in the study. The study was approved by the Ethical Committee of Vietnam National Children’s Hospital (approval number: 166/BVNTW-VNCSKTE).
: Not applicable.
: The authors declare that they have no competing interests.