Method for ascertaining denominators for evaluation of population coverage with pneumococcal vaccine

Immunization programs may collect numerator data for the estimation of pneumococcal vaccine coverage, but program evaluators do not have appropriate denominator data for estimation of pneumococcal vaccine coverage, particularly among those eligible for vaccine on the grounds of having chronic health conditions.

We partitioned the Alberta population into 6 mutually exclusive groups, all but one of which met Canadian recommendations for pneumococcal vaccination. Age-sex specific prevalence rates for each group were estimated using data on chronic health conditions from the Alberta over-sample of the 1996 Household component of the National Population Health Survey, from Alberta Health and Wellness rosters of nursing home residents, and from the Alberta Health Care Insurance Plan Stakeholder Registry. We applied these to Alberta Population Projections to estimate the numbers of persons who should be vaccinated.

The proportion of persons recommended for vaccination on the grounds of chronic health condition ranged from 1.5% among those aged less than 12 years to 36% among persons aged 80 years or older. The total number of persons recommended for vaccination at mid-year 2000 is estimated to be 638,561 (21.5% of the Alberta population).

This methodology provides denominators for the estimation of pneumococcal vaccine coverage and permits monitoring of local and regional progress towards national goals.