1 Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK; Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, the Netherlands.
2 Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
3 Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, the Netherlands.
4 Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: chris.drakeley@lshtm.ac.uk.