Bay Area Communities Are Home to Clusters of People Refusing Vaccines

by Liza Gross, KQED January 18, 2015 (excerpts)

Although vaccines are among the safest, most effective ways to protect children from major communicable diseases, many parents, for reasons that range from ill-informed to infuriating, still doubt this. As a result, many choose immunization schedules that defy science or refuse to vaccinate altogether.

If these parents were distributed randomly, their decisions would be less likely to harm others, especially babies too young for vaccination. But as previous studies have shown, parents who use “personal belief exemptions” to avoid school vaccination requirements often live in the same communities.

Now, in a study published Monday in the journal Pediatrics, researchers have (perhaps not surprisingly) found the same phenomenon among parents of infants and toddlers. These younger children face the highest risk of dying from whooping cough and other vaccine-preventable diseases....

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To look for at-risk communities, Lieu and her colleagues analyzed the medical records of 155,000 children in Kaiser’s system who lived in 13 Northern California counties and were born between 2000 and 2011. They were looking both for children who had received no vaccines and for children who had been “under-immunized,” meaning they had missed one or more shots by age three.

Researchers then matched these children’s vaccination records to their addresses, to see if these children were clustered geographically.

Across the 13 counties analyzed, the proportion of children who’d missed one or more shots increased from an average of 8 percent at the beginning of the study period to 12.4 percent at the end.

But that’s a broad geographic range. When the researchers drilled down to the county level, they found pockets of even higher rates of under-immunization ranging from 9.2 percent in Santa Clara County to 17.9 percent in Marin County between 2010 and 2012.

Five hot spots stood out between 2010 and 2012, including a 1.8-mile area in Vallejo, where 22.7 percent of kids were under-vaccinated. More than 10,000 toddlers lived within these five clusters.

The team also identified five clusters where all vaccines were refused for the babies and toddlers in the study:

• 10.2 percent of kids in an area from El Cerrito to Alameda
• 7.4 percent in northeastern San Francisco
• 6.6 percent in Marin and southwest Sonoma counties
• 5.5 percent Northeastern Sacramento County and Roseville
• 13.5 percent of kids in a small area south of Sacramento

Altogether, nearly 9,000 young children lived in these clusters.

In nearly every case, vaccine-refusal clusters overlapped with large areas of under-immunization....

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Last year, when a record number of California parents claimed personal belief exemptions, health officials reported the most measles cases seen here since 1995 and the most whooping cough cases since 1947.

Marin, Napa and Sonoma counties — where Lieu and her team found under-immunization clusters ranging from 17.5 to 18.1 percent between 2010 and 2012 —  had the highest rates of whooping cough in the state in 2014. During the same time, a review of state immunization records shows, vaccination rates for whooping cough at nearly two-thirds of Marin schools, a third of Napa schools and 37 percent of Sonoma schools fell below targets to halt disease spread.

Prof. Saad Omer at Emory University earlier found that clusters of personal belief exemptions contributed to the 2010 California whooping cough epidemic that killed 10 babies. Omer says that by using electronic medical records, Lieu and her team have developed a tool that can estimate risk earlier, without having to wait until children enter school.

The main problem with this clustering behavior, says Omer, is that every child’s risk for disease depends on what others do. That’s because no vaccine is 100 percent effective, so even a vaccinated child could get sick if exposed....

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Not long ago, a one-and-a-half-year-old boy was admitted to Offit’s hospital. He’d been seen at the hospital’s outpatient clinic at two, four, six and 12 months — all the times when kids get the pneumococcal vaccine. But his parents chose not to vaccinate and the staff didn’t push it, Offit says. “He came in with pneumococcal meningitis,” and then suffered a devastating brain herniation, Offit said. “He will never see, walk or speak again and probably won’t live past five. It’s not OK.”

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Flashback 50 Years--Same Phenomenon, Different Dominant Paradigm:  The Paranoid Style in American Politics, Harper's Magazine, Nov, 1964