Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1179252)
Received: 14 October 2018
Accepted: 16 April 2019
First Online: 15 May 2019
Ethics approval and consent to participate
: Ethical approval to carry out this research has been obtained by the Johns Hopkins School of Public Health Institutional Review Board in Baltimore, MD, USA, Sigma in Delhi India, and the University of Cape Town in South Africa.
: All others approved the final publication.
: The authors declare that they have no competing interests.
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