BACKGROUND:
Despite the success of the U.S. childhood immunization program, some racial/ethnic disparities still exist. Of all large racial/ethnic groups, Hispanics have the lowest rate of health coverage and are most likely to lack a usual source of health care. Most studies describing Hispanic health issues presume homogeneity. However, cultural and geographical differences exist among Hispanic heritage.

OBJECTIVE:
To examine immunization rates for the 4:3:1:3:3* series among U.S. Hispanic children aged 19 to 35 months over time, by ancestry and geographic location, and compared to non-Hispanic whites (*4+doses of diphtheria and tetanus toxoids and pertussis vaccine [DTaP/DTP], 3+doses of poliovirus vaccine, 1+ doses of measles-containing vaccine (MCV), 3+doses of Haemophilus influenzae type b vaccine (Hib), and 3+doses of hepatitis B vaccine).

METHOD:
We used the National Immunization Survey (NIS) data which measures immunization coverage among 19 to 35 month old U.S. children. Respondents self-classify their Hispanic ancestry. We compared 4:3:1:3:3 coverage among Hispanic and non-Hispanic white children using t-tests and compared coverage among Hispanic ancestries using a chi-squared test.

RESULT:
U.S. children 19 to 35 months of age who were of Hispanic ancestry increased in population from 21% in 1999 to 25% in 2003. In 2003, these children were less well immunized than non-Hispanic whites, 77%±2.1 compared to 82.5%±1.1. We found substantial geographic variability, and in some areas, immunization coverage among Hispanics was significantly higher than non-Hispanic whites. Immunization coverage did not vary significantly among ancestry groups.

CONCLUSION:
Hispanic children are a significant proportion of preschool aged children. Geographic differences in coverage could reflect differences in acculturation or local initiatives. Our findings reinforce the need to closely monitor state and local coverage, so interventions may be tailored to deliver culturally competent health care to the diverse community.

LEARNING OBJECTIVES:
To determine if immunization coverage rates among Hispanics are associated with various ancestries and geography.