Children’s Hospital at Westmead - The National Centre for Immunisation Research and Surveillance (NCIRS), National Centre for Immunisation Research and Surveillance, Children’s Hospital at Westmead - The National Centre for Immunisation Research and Surveillance (NCIRS), Children’s Hospital at Westmead - The National Centre for Immunisation Research and Surveillance (NCIRS), The University of Western Australia, Sydney Children's Hospital - Department of Immunology and Infectious Diseases, University of Melbourne - Infection and Immunity, University of Adelaide - Vaccinology and Immunology Research Trials Unit, Royal Darwin Hospital, affiliation not provided to SSRN, affiliation not provided to SSRN, Children’s Hospital at Westmead - The National Centre for Immunisation Research and Surveillance (NCIRS) and Children’s Hospital at Westmead - The National Centre for Immunisation Research and Surveillance (NCIRS)The University of Sydney, School of Public Health