Underimmunization of certain immigrant populations can place them at high risk of experiencing vaccine-preventable disease outbreaks.


We conducted a retrospective cohort study between January 1, 2008, and May 1, 2013, among children included in the Washington State Immunization Information System. We assessed receipt of 1 or more doses of measles-containing, hepatitis A, pneumococcal, and diphtheria-tetanus-acellular pertussis-containing vaccines between 12 and 23 months of age. We compared children with 1 or more parents born in Somalia, Ukraine, Russia, Mexico, or India to children with 2 parents born in the United States. Poisson regression models with robust SEs were used to provide prevalence ratios adjusted for maternal education and number of prenatal visits.


We identified 277 098 children, including 65 466 with foreign-born parents. Children of Somali-born parents were less likely to be immunized against measles than children of US-born parents (prevalence ratio: 0.82; 95% confidence interval: 0.80–0.84); this decrease became more pronounced over time (P < .01). No such disparity between these groups was observed with other vaccines. Compared with children of US-born parents, children of Ukrainian-born and Russian-born parents were less likely to be immunized, whereas children of Mexican-born and Indian-born parents were more likely to be immunized with any of the specified vaccines.


We found country-specific patterns of immunization that may reflect underlying cultural or other beliefs. Certain immigrant communities with higher rates of immunization refusal may be at risk for vaccine-preventable diseases and require new forms of public health outreach.

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