1 Bill & Melinda Gates Foundation, Seattle, WA, USA.
2 Medical Research Council, Respiratory and Meningeal Pathogens Research Unit, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa; Department of Science and National Research Foundation, Vaccine Preventable Diseases, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa.
3 Technology Accelerator, Save the Children, Seattle, WA, USA. Electronic address: aginsburg@savechildren.org.