Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1130522)
Received: 12 April 2017
Accepted: 22 November 2017
First Online: 11 December 2017
Ethics approval and consent to participate
: Ethical clearance for the surveys was obtained from the Nigeria National Research Health Ethics Committee, Federal Ministry of Health, Abuja, Nigeria, and the Institutional Review Board of the University of North Carolina at Chapel Hill, Chapel Hill, USA. Prior to conducting the interviews, field workers explained the objectives, procedures and associated risk and benefits of the study, and obtained informed verbal consent from each respondent.
: Not applicable.
: The authors declare that they have no competing interests.
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