Vaccine coverage of children in care of the child welfare system

Objective To assess vaccine coverage for a cohort of children who have been in the care of the child welfare system compared to children in the general population. Methods This retrospective cohort study used population-based administrative health data for a 2008 birth cohort of children from Alberta, Canada. We assessed coverage at ages 2 (n = 44,206) and 7 (n = 42,241) for three vaccines with different administration schedules for children in care (at any period before the age of assessment) and those who had never been in care, comparing them using risk differences and relative risks (RRs). We similarly assessed coverage for children not in care who shared characteristics of children in care. Results At age two, vaccination coverage for children in care ranged from 54.3% to 81.4%, depending on vaccine. In comparison, coverage for those not in care ranged from 74.2% to 87.4%. At age seven, coverage for children in care ranged from 53.1% to 65.3%, compared to 76.6% to 83.4% for those not in care. For all vaccines at both ages, the risk for being under-vaccinated was higher for children in care (e.g., diphtheria, pertussis, tetanus, polio, Haemophilus influenzae type b at age 7: RR 2.01, 95% confidence interval [CI] (1.74-2.32). Even for children not in care who had characteristics similar to children in care, we found children in care had lower coverage. Conclusion Children in care have consistently lower vaccine coverage than children not in care. Policies and practices should promote optimal access to vaccination for these children.