Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk|Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. francesc.coll@lshtm.ac.uk