Funding for this research was provided by:
Newton Fund (216383378)
GB Department for Economy (DFEGCRF-21)
Received: 28 August 2018
Accepted: 13 January 2019
First Online: 30 January 2019
Ethics approval and consent to participate
: Our study received ethical clearance from Institutional Review Board of Hanoi University of Public Health in Vietnam. No. 309/2017/YTCC-HD3. All participants in the study provided written consent, and were fully informed about how their information would be used.
: All participants within this study were informed how their data would be used, and gave their consent in written form.
: The authors declare that they have no competing interests.