affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Public Health Ontario, University of British Columbia (UBC) - School of Population and Public Health, affiliation not provided to SSRN, British Columbia Children's Hospital Research Institute - Vaccine Evaluation Center, affiliation not provided to SSRN, British Columbia Centre for Disease Control, University of British Columbia (UBC), University of Alberta, Queen's University - Institute for Clinical Evaluative Sciences and Université Laval - Department of Social and Preventive Medicine