Funding for this research was provided by:
Department of Education of Guangdong Province (2017KQNCX162)
Guangzhou Municipal Health Commission (20181A011103)
Project of Liwan District Science and Technology (201804015)
Received: 9 August 2019
Accepted: 26 August 2020
First Online: 3 September 2020
Ethics approval and consent to participate
: Not applicable
: Not applicable.
: The authors declare that they have no competing interests.