1. Heidelberg Institute of Global Health, Heidelberg University and University Hospital, 69120 Heidelberg, Germany
2. Department of Economics and Centre for Modern Indian Studies, University of Goettingen, 37073 Göttingen, Germany
3. Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA 02115, USA
4. Africa Health Research Institute, Somkhele, Mtubatuba, 3935, South Africa
5. Division of Primary Care and Population Health, Stanford University, Stanford, CA 94305, USA
6. Oxford Martin School, Oxford University, Oxford OX1 3BD, UK