Funding for this research was provided by:
Guangzhou Health Care Collaborative Innovation Major Project (201704020219)
Project of the Guangdong Key Laboratory of Tropical Diseases (RDBYJ2018001)
Received: 30 October 2019
Accepted: 27 March 2020
First Online: 14 May 2020
Ethics approval and consent to participate
: This study was reviewed and approved by the Guangdong International Travel Healthcare Center Institutional Review Board Committee. As only secondary data was used in this study, consent to participate was not required.
: Not applicable.
: The authors declare that they have no competing interests.