Received: 18 November 2020
Accepted: 4 February 2021
First Online: 15 February 2021
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee for Human Research of the Beijing Tongren Hospital Capital Medical University and adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained from all the volunteers after providing a detailed explanation of the study.
: The informed consent for the study is attached, and the paper was approved by the parents of the participants. All the original documents were kept and managed by the hospital.
: Non-financial competing interests.