Liu, Fange
Lv, Di
Wang, Lumin
Feng, Xiaoyu
Zhang, Rongjun
Liu, Wendong
Han, Wenchao
Article History
Received: 6 January 2022
Accepted: 25 May 2022
First Online: 16 June 2022
Declarations
:
: This study was carried out under the guidance of the Qingdao Municipal Center for Disease Control and Prevention [2017] No. 29 document, and was approved by The Institutional Research Human and Animal Ethics Committee Qingdao Municipal Hospital (application number: 024). All study procedures were in accordance with the ethical standards of the Declaration of Helsinki. Informed consent obtained from all students parent.
: Not applicable.
: The author has no conflicts of interest to declare.