Shingles in Alberta: before and after publicly funded varicella vaccination.

Purpose: A universal publicly funded chickenpox vaccination program was implemented in Alberta in 2002. We examine the epidemiology of medically attended shingles in Alberta from 1994 to 2010.

Methods: Incident shingles cases (earliest health service utilizations for ICD-9 053 or ICD-10-CA B02) and their co-morbid conditions for the 12 months prior to shingles diagnosis were identified from the records of Alberta's universal, publicly funded health-care insurance system for 1994-2010. Shingles diagnostic codes at least 180 days after the first were classified as recurrent episodes. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Plan Registry. Annual age- and sex-specific rates were estimated. We estimated the proportion of all cases that were hospitalized. We explored the pattern of rates for sex, age-group co-morbidity and year effects and their interactions.

Results: Crude rates of shingles increased over the interval 1994-2010. Most persons had only a single episode of shingles; 4% of cases were hospitalized. Shingles rates were higher among females than males. While only 2% of shingles cases had one or more co-morbidities, this proportion was also higher for females than males. Prior to 2002, all age groups of both sexes experienced increasing annual rates of shingles. However, there was a sharp decline in the rate of shingles for both females and males under the age of 10 years for 2002-2010, the period in which there was publicly funded chickenpox vaccination.

Conclusion: The declining rates of shingles among persons under the age of 10 years are consistent with an impact of the chickenpox vaccination program. The trend of increasing rates of shingles among older persons began prior to implementation of vaccination.