Zhang, Yafeng
Tian, Wei
Xin, Yuqi
Zhou, Quan
Yan, Guangcan
Zhou, Jianqiu
Wang, Bin
Tao, Yuchun
Fan, Lihua
Wang, Limin
Article History
Received: 30 July 2021
Accepted: 28 December 2021
First Online: 11 January 2022
Declarations
:
: This study was approved by the Ethics Committee of Harbin Medical University (Study: ID HMUIRB20210003) and was conducted according to the tenets of the 1964 Helsinki Declaration and its later amendments. We sought permission from each school and the participants’ verbal informed consent. Written informed consent was obtained from the guardians with the assistance of teachers.
: Not applicable.
: The authors declare that they have no competing interests.