Margaret L. Russell, MD PhD¹, Nikolaos Yiannakoulias, MA², Larry W Svenson, BSc², Donald P Schopflocher, PhD², and Karen B. Grimsrud, MD, MHSc³. (1) Community Health Sciences, University of Calgary, 3330 Hospital Dr NW, Calgary, AB T2N 4N1, Canada, 403 220 4279, mlrussel@ucalgary.ca, (2) Health Surveillance Branch, Alberta Health and Wellness, P O Box 1360 STN MAIN, Edmonton, AB T5J 2N3, Canada, (3) Office of Provincial Health Officer, Alberta Health and Wellness, PO Box 1360, Station MAIN, Edmonton, AB T5J 2N3, Canada

BACKGROUND: Varicella vaccine was licensed in Canada in 1998. Alberta was the second Canadian province (after Prince Edward Island) to introduce a universal publicly funded varicella vaccination program in 2001. PURPOSE: To describe the epidemiology of non-fatal cases of chickenpox for which publicly funded health services were utilized for the period 1983 - 2002 METHODS: Residents of the province of Alberta are eligible for coverage under a publicly funded and universally available health-care system. We used this database to identify cases of chickenpox for which people had used health services; i.e., been hospitalized, visited an emergency room or made a visit to a medical doctor. The earliest dated utilization of a health service for which there was an ICD9-CM code of 052.xx was used as the onset date for cases of chickenpox. Incidence rates were estimated using the population of those registered with the Alberta Health Care Insurance Registry for denominators. RESULTS: The incidence of chickenpox significantly declined over the period 1994 – 2002 (most steeply for the interval 2001 – 2002). This decline began prior to vaccine licensure and continued at a steeper slope following introduction of the publicly funded program. CONCLUSION: Rates of incident varicella for which health care services were utilized began to decline in Alberta prior to both vaccine licensure and the publicly funded vaccination program. This pattern is consistent with one or more of changes in the epidemiology of disease or changes in patterns of health service utilization.

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