Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1142884)
Received: 5 March 2019
Accepted: 18 June 2019
First Online: 19 July 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Ethics Committee of the Public Health Foundation of India. All participants provided written informed consent, and for those who could not read or write, the participant information sheet and consent form were explained by the trained interviewer and a thumb impression is obtained.
: Not applicable.
: DB, YA, and PN are employees of the Bill & Melinda Gates Foundation, India Country Office, New Delhi. The other authors declare that they have no competing interests.