1National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW 2145, Australia; Australian National University, National Centre for Epidemiology and Population Health, ACT 2600, Australia. Electronic address: zoe.croker@health.nsw.gov.au.
2Australian National University, National Centre for Epidemiology and Population Health, ACT 2600, Australia.
3National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW 2145, Australia.
4National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW 2145, Australia; The University of Sydney Faculty of Medicine and Health, NSW 2006, Australia.
5National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW 2145, Australia; The University of Otago Department of Women's and Children's Health, School of Medicine, Dunedin, New Zealand.
6National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW 2145, Australia; The University of Sydney School of Public Health, NSW 2006, Australia.