1 National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Department of Family and Community Medicine, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia. Electronic address: malfelali@kau.edu.sa.
2 National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; School of Public Health, The University of Sydney, Sydney, NSW, Australia.
3 National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; The Executive Administration of Research, King Abdullah Medical City (KAMC), Makkah, Saudi Arabia.
4 National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, NSW, Australia.