VARICELLA-RELATED HOSPITALIZATIONS IN IMPACT CENTERS AFTER INTRODUCTION OF 1- AND 2-DOSE VARICELLA VACCINATION PROGRAMS BETWEEN 2000 AND 2015

Abstract

Abstract BACKGROUND The Canadian Immunization Monitoring Program ACTive (IMPACT) conducts active surveillance for varicella-related hospitalizations in 12 paediatric tertiary care centres, starting Apr 1999. OBJECTIVES This study was to determine the hospitalization trends in relation to vaccine program introduction in the provinces, between 2000 and 2015. DESIGN/METHODS Demographic data of varicella cases from the 12 IMPACT centers were analysed. The cases were subdivided into three groups (A, B and C), combining provinces with approximately the same time periods at introduction of 1-dose and 2-dose vaccination programs (see results). RESULTS The mean number of hospitalizations per year declined during the 1-dose and 2-dose eras in each group of provinces, as follows: CONCLUSION Varicella hospitalizations declined by 63–77% but reached a plateau during the 1-dose vaccine era. There was a further decline to 81–89% of baseline in the two groups which instituted 2-dose vaccine programs in 2011–12, but too early to document any further decline in Group C, the provinces which initiated 2-dose programs in 2014–16. Introduction of 2-dose programs appear to have provided further benefit, after 1-dose programs in Canada.