Funding for this research was provided by:
Japan Society for the Promotion of Science (JP18K10540)
Received: 13 December 2020
Accepted: 15 March 2021
First Online: 30 March 2021
: Ethical approval for this study was obtained from the Epidemiology Ethical Review Committee of University of the Ryukyus (Clearance No. 1367) and the National Ethics Committee for Health Research of Laos PDR (Clearance No. 24). All participants provided verbal consent to be included in this study.
: Not applicable.
: The authors declare that they have no competing interests.