1. Umeå Centre for Global Health Research, Division of Epidemiology and Global Health, Department of Public Health and Clinical Medicine, Umeå University , Umeå, Sweden
2. Centre for Population Studies, Ageing and Living Conditions Programme, Umeå University , Umeå, Sweden
3. Institute of Public Health, Medical Faculty, University of Heidelberg , Heidelberg, Germany
4. Nouna Health Research Centre , Nouna, Burkina Faso