affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Government of the People's Republic of China - Ministry of Health, affiliation not provided to SSRN, affiliation not provided to SSRN, Institute for Clinical Evaluative Sciences (ICES), Queen's University - Institute for Clinical Evaluative Sciences, British Columbia Centre for Disease Control, affiliation not provided to SSRN, Ministry of Health - National Immunization Program, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, University of British Columbia (UBC) - School of Population and Public Health, University of Auckland, Queen's University - Institute for Clinical Evaluative Sciences, affiliation not provided to SSRN, The University of Hong Kong - University of Hong Kong, affiliation not provided to SSRN, affiliation not provided to SSRN, University of Auckland, University of Auckland, University of Melbourne - Murdoch Children's Research Institute, University of Cincinnati and University of Melbourne