Funding for this research was provided by:
Beijing Natural Science Foundation (7194336)
Natural Science Foundation of China (31900805)
Received: 11 February 2020
Accepted: 8 October 2020
First Online: 17 October 2020
Ethics approval and consent to participate
: The study procedure was reviewed and approved by the Peking University Sixth Hospital natural and computational science research and community service reviewers, and the approval number was 2020-4-9-1. Informed consent was received online before the respondents began the questionnaire. All participants were informed that they have the right not to participate in the study, and only those who provided informed consent were able to respond to the survey. Teenagers aged between 8 and 18 were approved by the ethics committee to voluntarily participate in the study without parental consent. All information obtained in the study was kept confidential.
: Not applicable.
: The authors declare that they have no competing interests.