1. Department of International Health, University of Tampere Medical School, Tampere 33014, Finland
2. Department of Paediatrics, Tampere University Hospital, Tampere 33014, Finland
3. College of Medicine, University of Malawi, Blantyre P/Bag 360, Malawi
4. Singapore Clinical Research Institute, 138669, Singapore
5. National Public Health Institute, Helsinki 30, Finland