The effectiveness of shingles vaccine among Albertans aged 50 years or older: A retrospective cohort study

Abstract
Purpose: This study evaluated the effectiveness of the shingles vaccine in preventing new cases of shingles among Alberta residents aged 50 and older from 2009 to 2015, utilizing administrative health data.Methods: The cohort included Albertans registered with the Alberta Health Care Insurance Plan (AHCIP) as of June 30, 2009, who were aged 50 or older. Vaccination status was determined from the provincial pharmaceutical information network. New cases of shingles were identified through inpatient and outpatient/community care data, with incident shingles defined as the first recorded instance of ICD 9-CM 053 or ICD-10-CA B02. Beginning November 1, 2009, individuals without a history of shingles or vaccination were tracked until November 1, 2015 (6 years), or until they experienced shingles, died, or had their AHCIP coverage canceled (including moving out of Alberta). Vaccine effectiveness (VE) was calculated as the inverse of the relative risk of developing incident shingles in each year post-vaccination, compared to the period at risk without vaccination, while controlling for age, sex, income quintile, and immune-compromising conditions (identified through physician claims, inpatient data, and cancer registry information).Results: The cohort comprised 1,094,236 individuals, with 85,439 (7.80%) receiving the shingles vaccine. The incidence rate of shingles was 9.03 [95% CI: 8.95, 9.11] cases per 1,000 person-years, totaling 49,243 cases. The adjusted VE in the first year post-vaccination was 50.02% [95% CI: 44.71%, 54.83%], decreasing to 14.00% [95% CI: -20.99%, 38.88%] by the fifth year, indicating a diminishing effect.Conclusions: Our results align with findings from other population-based studies and provide valuable data for policymakers considering public funding for the shingles B02 vaccine.