Parents who do not vaccinate their children tend to congregate in geographic hot spots, posing significant public health risks, found a Kaiser Permanente study published in Pediatrics.
Researchers analyzed EHR records of more than 154,000 members of Kaiser Permanente Northern California with continuous membership from birth to 36 months old.
Researchers identified five significant clusters of undervaccinated children where the underimmunization rate ranged from 18 percent to 23 percent. The rate of underimmunization outside of these clusters was 11 percent. Researchers defined underimmunization as children who received some, but not all, vaccines.
Additionally, researchers found the rate of parental refusal to vaccinate their children corresponding with clusters. Inside the clusters, parental refusal to vaccinate children was between 6.6 percent and 10.2 percent. Outside the clusters, parent refusal to vaccinate children was 2.6 percent.
"The Kaiser study is significant because all children are insured and thus have equal access to preventive care," according to a San Jose Mercury News report discussing the study. "What it reveals, instead, are cultural differences."
Researchers concluded that targeted interventions to these clusters could help boost vaccination rates and improve public health of the communities.