Epidemiology of varicella among immigrants and non-immigrants in Quebec, Canada, before and after the introduction of childhood varicella vaccination: a retrospective cohort study

摘要

Background Many immigrants are susceptible to varicella on arrival to Canada because of different transmission dynamics in their countries of origin and scarcity of vaccination. Universal childhood vaccination programmes decrease varicella incidence rates through herd immunity, but the accumulating number of susceptible adult immigrants could remain at risk for severe varicella. Our aim was to describe the epidemiology of varicella among immigrants and non-immigrants before and after childhood varicella vaccination.