Vaccine
Volume 33, Issue 36, Pages 4359-4658 (26 August 2015)
http://www.sciencedirect.com/science/journal/0264410X/33/36

Exploring the heterogeneity among partially vaccinated children in a population-based cohort
Original Research Article
Pages 4572-4578
Christopher A. Bell, Kimberley A. Simmonds, Shannon E. MacDonald
Abstract
Introduction
Vaccination status is often categorized as complete or not-complete. This ignores the potentially important heterogeneity in children whose vaccinations are not-complete. We sought to subcategorize not-completely vaccinated children and determine whether characteristics differed among these subgroups.
Methods
This retrospective cohort study assessed vaccination status at 2 years of age for 43,965 children in the 2008 Alberta (Canada) birth cohort who were registered with provincial vital statistics records. Children were categorized (based on the five routinely scheduled childhood vaccines) as complete, incomplete, selective, or non-vaccination status. Characteristics derived from administrative health databases were used to determine factors associated with vaccination status.
Results
Population-level vaccination status at 2 years of age was found to be: 71.1% complete and 28.9% not complete (21.9% incomplete, 2.0% selective, and 5.1% non-vaccinated). Midwife delivery at home, compared to physician delivery in hospital, was strongly associated with non-vaccination status (adjusted odds ratio [aOR] 51.70, 95% CI 37.10–72.10). Factors that might pose barriers to vaccination, such as single marital status (aOR 1.58, 95% CI 1.49–1.67), large number of household children (≥4 vs. 1) (aOR 3.24, 95% CI 2.95–3.54), and multiple household moves (≥3 vs. 0) (aOR 1.69, 95% CI 1.35–2.10), were all strongly associated with incomplete vaccination status.
Conclusions
Of the children who were not completely vaccinated at age 2, the vast majority had started but not completed the vaccination series, while a smaller number were selectively vaccinated or not vaccinated at all. Distinct differences are present among these groups that require attention when addressing vaccine coverage.