Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1199872)
Text and Data Mining valid from 2019-09-07
Received: 16 May 2019
Accepted: 20 August 2019
First Online: 7 September 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human or animal subjects performed by the any of the authors.