Neighbourhood influence on the fourth dose of diphtheria-tetanus-pertussis vaccination

Objectives Using 542,159 vaccination records from children born between April 1, 2007, and March 31, 2012, in the Michigan Care Improvement Registry and data from the American Community Survey, we determine if neighbourhood-level characteristics at the Census tract level and block level are associated with low uptake of the fourth dose of diphtheria–tetanus–acellular pertussis vaccine (DTaP4). Study design This study was a cross-sectional study. Methods We used exploratory factor analysis to determine important socio-economic factors at the Census block level and tract level. We then used generalised estimating equations to test the relationship between block- and tract-level socio-economic factors and DTaP4 uptake. Results DTaP4 coverage was 88.6% (95% confidence interval [CI]: 88.4%–88.7%) in Michigan. At the Census tract level, two factors surfaced as important for DTaP4 vaccination: ‘affluence’ (Cronbach's alpha = 0.88) and ‘socio-economic disadvantage’ (Cronbach's alpha = 0.89). At the Census block level, one factor was important: ‘affluence’ (Cronbach's alpha = 0.90). Affluence may relate to knowledge about medical exemptions and antivaccination sentiment, while socio-economic disadvantage may indicate limited access to healthcare resources. Children in high-affluence tracts had 1.08% lower vaccination coverage (95% CI: −1.62% to −0.55%) than children in low affluence tracts. Children in low socio-economic disadvantage tracts had 2.92% higher coverage than children in high socio-economic disadvantage tracts (95% CI: 2.58%–3.26%). Conclusions This study articulates the need to further understand the contribution of neighbourhood-level characteristics, from both affluent and socioeconomically disadvantaged areas to low vaccination rates. Developing a better understanding of these social environmental factors will help determine useful community-level interventions to improve vaccination rates and reduce disease burden.