Trends in Disparity of Vaccination Coverage Between Poverty Levels among Children Aged 19-35 Months, National Immunization Survey, 2000-2007

Background:
The US Healthy People 2010 plan includes objectives for increasing childhood vaccination coverage and the overarching goal of eliminating health disparities.

Objectives:
Compare coverage of the 4:3:1:3:3:1 standard vaccination series among children living above the poverty level to those living below the poverty level; evaluate trends in disparity between the two poverty levels from 2000-2007.

Methods:
Data from children aged 19-35 months in the 2000-2007 National Immunization Survey were analyzed. Bivariate analysis was used to estimate unadjusted disparity of series-complete vaccination coverage between poverty levels. Multivariable logistic regression was applied to evaluate the effect of poverty level after adjusting for various demographic factors. Linear trends in unadjusted and adjusted disparities were assessed.

Results:
Vaccination coverage among children living above the poverty level was 3.2-7.9 % (p≤0.02) higher than among children living below the poverty level in each year from 2000-2007. After controlling for other demographic factors, the adjusted disparity between poverty levels was reduced to 0.3-2.2% (p≥0.18).
Unadjusted poverty disparities in vaccination coverage narrowed from 2000-2007, decreasing an average of 0.5% per year (p=0.02); after adjusting for other factors, the disparity decreased an average of 0.4% per year (p=0.11).

Conclusions:
Disparity in vaccination coverage between children living above vs. below poverty level persists, but these results suggest disparity may be declining. Interventions to improve coverage among children living below poverty should consider potential barriers to vaccination: low level of mother's education, younger maternal age, or single mother with more than one child. Since most children living below poverty are eligible for the Vaccines for Children Program (VFC), efforts should ensure that these families are aware of the entitlement and facilitate their access to VFC providers.