Disparities in childhood vaccination coverage: Findings of the National Immunization Survey (NIS), 2013

Background

Childhood vaccination coverage is monitored by the Centers for Disease Control and Prevention to provide national, state and selected local area coverage estimates, to assess progress towards Healthy People 2020 targets, and to identify sociodemographic disparities.

Methods

NIS is a dual-frame random-digit-dialed telephone survey, with follow up immunization history questionnaires (IHQs) mailed to vaccination providers. The parents of children 19-35 months were sampled from landlines and cell phones in the 50 states, District of Columbia, and selected local areas. Telephone interviews were used to obtain demographic information and request consent to contact the child’s provider(s) to obtain vaccination histories. Household interview and provider-reported data were analyzed using SUDAAN to examine vaccination coverage levels by race/ethnicity and poverty status. Data were weighted to be representative of the population of children 19-35 months. Logistic regression was used to examine differences among racial/ethnic populations, controlling for poverty status. Statistical analyses were conducted using t-tests, using weighted data and accounting for the complex survey design.

Results

In 2013, children living below the federal poverty level had lower vaccination coverage compared with children living at or above the poverty level for all childhood vaccines, with percentage point differences ranging from 3.7% to 12.6%.   Additionally, black children had significantly lower vaccine coverage compared to white children for >4 doses diphtheria tetanus and acellular pertussis vaccine (DTap; 74.7% vs 85.3%), full series of haemophilus influenzae type b vaccine (Hib; 74.9% vs 84.2%), >4 doses pneumococcal vaccine (PCV; 76.1% vs 84.1%), rotavirus vaccine (62.1% vs 74.8%), and the combined 7-vaccine series (65.0% vs 72.1%). After adjustment for poverty status, this racial/ethnic disparity was reduced but remained statistically significant, except for the combined 7-vaccine series.

Conclusions

This disparity in vaccination coverage signals that more interventions or policy-related efforts are needed for identified subgroups. Additional analyses should be conducted to better understand poverty and racial/ethnic disparities, including an examination of health insurance status, number of children in household, maternal education and marital status, and state-level factors. These analyses can help inform evidence-based interventions.  Disparities in vaccination coverage must be addressed to protect all children from vaccine-preventable diseases.