Received: 24 September 2020
Accepted: 31 January 2021
First Online: 9 February 2021
Ethics approval and consent to participate
: This study was performed in strict accordance with the human subject protection guidance of the Ministry of Science and Technology of China, and the study protocol was approved by the ethics committee of Shenzhen Children’s Hospital. Written consent was obtained from the guardians of all participants before data collection.
: Not applicable.
: The authors have no potential conflicts of interest.