Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1119808)
Text and Data Mining valid from 2020-01-08
Received: 11 October 2018
Accepted: 30 December 2019
First Online: 8 January 2020
Ethics approval and consent to participate
: Not applicable (secondary analysis of existing data).
: Not applicable.
: The authors declare that they have no competing interests.