1 Umeå Centre for Global Health Research and Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden; MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, Education Campus, University of Witwatersrand, Parktown, South Africa.
2 College of Medicine and Allied Health Sciences, Freetown, Sierra Leone.
3 MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, Education Campus, University of Witwatersrand, Parktown, South Africa; School of Population Sciences and Health Services Research, Faculty of Life Sciences and Medicine, King's College London, London, UK. Electronic address: [email protected].
4 Department of Global Health and Population, Harvard T H Chan School of Public Health, Boston, MA, USA.
5 MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, Education Campus, University of Witwatersrand, Parktown, South Africa; AGE Research Group, Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
6 W1, Oriental Plaza, No.1 East Chang An Ave, Beijing, China.