All Canadian provinces and territories have had routine immunization programs for one-dose varicella vaccination since 2007, a strategy that has reduced varicella disease rates dramatically. However, breakthrough cases still occur, and some cases are severe. There is increasing evidence that immunity to one dose of the vaccine can wane in a vaccinated population, and the disease may be shifting to an older age group that can experience more severe disease and more complications. This statement presents the rationale for a two-dose immunization strategy in Canada, as well as recommendations for a routine two-dose varicella vaccine schedule for all Canadian children. Children who have received one dose of varicella vaccine and have not had breakthrough infection should receive another dose of varicella vaccine.
Keywords: Adolescent; Canada; Canadian Paediatric Society vaccine recommendations; Children; Immunization, Vaccine schedule; Varicella vaccine.