Funding for this research was provided by:
Bill and Melinda Gates Foundation
Received: 2 May 2017
Revised: 22 June 2017
Accepted: 23 June 2017
First Online: 3 August 2017
Compliance with ethical standards
: This manuscript reflects original work that has not previously been published in whole or in part and is not under consideration elsewhere. All authors have read the manuscript and have agreed that the work is ready for submission and accept responsibility for its contents. The authors of this paper have complied with all ethical standards and do not have any conflicts of interest to disclose at the time of submission. The funding source played no role in the design of the study, the analysis and interpretation of data, and the writing of the paper. The study did not involve human participants and/or animals; therefore, no informed consent was needed.
: The authors declare that they have no conflicts of interest.
: This research was funded by the Bill & Melinda Gates Foundation.