1. Institute for Basic Medical Sciences, Faculty of Medicine, University of Oslo, Domus Medica, Sognsvannsveien 9, 0372 Oslo, Norway
2. Health Systems Research Unit, Medical Research Council
3. Adolescent Health Research Unit, University of Cape Town, Cape Town, South Africa
4. International Center for Reproductive Health, Ghent University, Ghent, Belgium
5. Department of Epidemiology and Biostatistics, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
6. MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK