1. Oxford University Clinical Research Unit, University of Oxford, Centre for Tropical Medicine, 764, Vo Van Kiet, Ho Chi Minh City, Vietnam
2. Department of Pure and Applied Chemistry, Technology and Innovation Centre, University of Strathclyde, 99 George St, Glasgow G1 1RD, UK
3. Centre for Tropical Medicine and Global Health, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG, UK
4. MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, Level 2, Faculty Building South Kensington Campus, London SW7 2AZ, UK