Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1148464)
Received: 19 December 2019
Accepted: 1 May 2020
First Online: 24 May 2020
Ethics approval and consent to participate
: This study was based on administrative data in the public domain. No human subjects were involved.
: This study does not contain any individual person’s data.
: The authors declare no competing interests.