The impact of the universal infant varicella immunization strategy on Canadian varicella-related hospitalization rates

Introduction

Varicella vaccine was introduced to the infant immunization schedule in each province or territory between 2000 and 2007 as a result of the Canadian Immunization Strategy. The impact of vaccinating children against this disease is potentially far reaching, as immunization may also benefit those segments of the population not immunized. The objective of this paper is to examine the effects of varicella vaccine on related hospitalizations across the entire Canadian population.

Methods

This study is an ecological study using annual hospitalization rates in all ten provinces between 1990 and 2010.

Results

There were decreased varicella-related hospitalization rates for all ages across Canada following the introduction of varicella vaccination programs. The majority of changes in hospitalization rates were greater than 70% across all ages less than 40. Statistically significant declines in hospitalization were found for children aged 1–4 (ranges from 65 to 93%), and children less than 1 (ranges from 48 to 100%). Adults aged 20–39 and 40–59 also experienced statistically significant declines (55–100%, and 39–76% respectively).

Conclusion

Results suggest that decreased circulation of varicella appears to significantly contribute to declines in varicella-related hospitalizations for infants <1, as well as adults aged 20–39.