Kelly Wyres1, Kathryn Holt2. 1. Department of Infectious Diseases, Monash University, Melbourne, VIC 3004, Australia. 2. Department of Infectious Diseases, Monash University, Melbourne, VIC 3004, Australia; Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: kat.holt@lshtm.ac.uk.