Zheng, Wenlong
Zhang, Hui
Wang, Dezheng
Wang, Chong
Zhang, Shuang
Shen, Chengfeng
Li, Wei
Jiang, Guohong
Article History
Received: 8 January 2021
Accepted: 20 October 2021
First Online: 12 November 2021
Declarations
:
: This study was implemented as a register-based studybased on anonymous data at TJCDC and was approved bythe Ethics Committee of Tianjin Centers for Disease Control and Prevention. The Ethics.Committee of Tianjin Centers for Disease Control and Prevention waived the need for informed consent because register-based studies on anonymous data do not require writtenconsent in Tianjin, according to the good effects for public health and no invasion of privacy. The fist author Wenlong Zheng applied and get administrative permission of TJCDC. All methods used in the study were performed in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.