Funding for this research was provided by:
World Health Organization
Received: 17 April 2020
Accepted: 31 July 2020
First Online: 3 September 2020
Ethics approval and consent to participate
: Ethics approval for this project was obtained from the Ethics Review Committee of the World Health Organization, Geneva, Switzerland and the National Ethics Committee for Health Research, Ministry of Health, Kingdom of Cambodia (No. 160 NECHR 2018 and No. 162 NECHR 2019).
: Not applicable.
: The authors declare that they have no competing interests.