Funding for this research was provided by:
Fundamental Research Funds for Central Universities of the Central South University (2019zzts328)
Health and Family Planning Commission of Hunan Province (C2014-17)
Science and Technology Bureau, Changsha (kh2005021)
Hunan Provincial Science and Technology Department (2018SK2061)
Received: 6 December 2020
Accepted: 23 May 2021
First Online: 3 June 2021
: The research was approved by the ethics committees of the Xiangya School of Public Health Central South University (XYGW-2018-26). Every participant, or their proxy respondent, provided informed written consent before participating in the study.
: Not applicable.
: The authors declare that they have no competing interests.