1. From the Departments of Paediatrics (P.A.B., N.C.), and Microbiology and Immunology (R.R.-B.), University of Melbourne, Parkville, Australia; Infectious Diseases Unit, Department of General Medicine (P.A.B., N.C.), and Infection, Immunity and Environment Theme, Murdoch Children’s Research Institute (P.A.B., R.R.-B., N.C.), Royal Children’s Hospital Melbourne, Parkville, Australia; and Menzies School of Health Research (J.R.C.), Charles Darwin University, Casuarina, Australia.