Zhang, Yunyun
Guan, Hongyu
Ding, Yuxiu
Xue, Jing
Article History
Received: 1 July 2022
Accepted: 4 May 2023
First Online: 13 May 2023
Declarations
:
: The trial was approved by the Stanford University Institutional Review Board (Protocol No. ISRCTN03252665). Permission was received from local Boards of Education in each region and from the principals of all schools. The principles of the Declaration of Helsinki were followed throughout. Written informed consent was obtained from at least one parent for all child participants.
: Not applicable.
: The authors declare no competing interests.