Researchers Identify Clusters of Unvaccinated Children in California

Researchers have identified five areas in California with clusters of unvaccinated children, according to a new study published in the journal Pediatrics, the Los Angeles Times reports.

Details of Study

For the study, researchers examined the electronic health records of 154,424 children born between 2000 and 2011 (Brown, Los Angeles Times, 1/18). All children involved in the study were members of Kaiser Permanente Northern California (Seaman, Reuters, 1/19).

The study included children who were either:

• Unvaccinated; or
• Under-immunized, meaning they had at least one vaccination by age three, but not all recommended vaccinations.

Findings

The researchers identified five areas where a high percentage of children had not been vaccinated, including:

• An area south of Sacramento, where 13.5% of children were unvaccinated or under-immunized;
• An area from El Cerrito to Alameda, where 10.2% of children were unvaccinated or under-immunized;
• Marin and southwest Sonoma counties, where 6.6% of children were unvaccinated or under-immunized;
• Northeastern Sacramento County and Roseville, where 5.5% of children were unvaccinated or under-immunized; and
• Northeastern San Francisco, where 7.4% of children were unvaccinated or under-immunized (Gross, "State of Health," KQED, 1/18).

In comparison, the average rate of vaccine refusal among Kaiser Northern California members outside of those clusters was 2.6%.

The study found that Asian children were more likely to be vaccinated than white, Latino or African American children (Krieger, San Jose Mercury News, 1/19).

In addition, areas with higher percentages of residents with graduate degrees and those with individuals below the poverty line were most likely to have higher percentages of under-immunized children (Los Angeles Times, 1/18).

Tracy Lieu, director of Kaiser’s Division of Research, said identifying the clusters can help doctors target specific areas and children for disease prevention (Reuters, 1/19).