Funding for this research was provided by:
Centers for Disease Control and Prevention (#200-2010-33319)
University of North Carolina at Chapel Hill
National Institutes of Health (R25CA57712)
University of Texas Health Science Center at Houston
University of Texas MD Anderson Cancer Center
Oklahoma Tobacco Settlement Endowment Trust (092-016-0002)
Received: 13 November 2017
Accepted: 19 January 2018
First Online: 14 February 2018
Ethics approval and consent to participate
: The Institutional Review Board of Abt Associates and the Ethics Committee of Centers for Disease Control and Prevention in the US, and Hanoi School of Public Health’s Ethical Review Board in Vietnam approved the study’s research protocol and questionnaires. All of these boards approved oral informed consent because of potential severe consequences for participants if there were a confidentiality breach associated with a written consent.
: Not applicable.
: The authors declare that they have no competing interests.
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