Funding for this research was provided by:
National Natural Science Foundation of China (81973053)
Received: 13 January 2022
Accepted: 27 April 2022
First Online: 10 May 2022
: The study was approved by the Institutional Review Board of Peking University Health Science Center (No. IRB00001052-20026). All methods were performed in accordance with the relevant guidelines and regulations. Since the anonymous research presents no more than minimal risk of harm to subjects and involves no procedures for which written consent is normally required outside of the research context, the Institutional Review Board of Peking University Health Science Center has waived the requirement for us to obtain a signed consent form for both the children participants and the parental participants. According to the requirement of Institutional Review Board of Peking University Health Science Center, we have fully introduced the purpose and content of this survey in the instruction of the electronic questionnaire. If subjects agreed to participate in the investigation after reading the instruction, they began to answer the questionnaire. Otherwise, they can withdraw from the research at any time.
: Not applicable.
: The authors declare that they have no competing interests.