Article History
Received: 3 November 2016
Accepted: 3 January 2018
First Online: 30 January 2018
Ethics approval and consent to participate
: The study protocol and instrument material were reviewed and cleared by the Hanoi School of Public Health Institutional Review Board (Application No. 015–238/DD-YTCC). Individual verbal informed consent was obtained from the participant at the beginning of each interview.
: Not applicable.
: The authors declare that they have no competing interests.
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