In light of the recent Disneyland measles outbreak, deeper scrutiny has been given to unvaccinated children and, according to a study released Monday in the Pediatrics journal, parents who choose to use the personal belief exemption to not vaccinate their children tend to cluster geographically (i.e., live near each other or in the same areas).
Why is this news alarming for other parents?
Vaccinations depend on a herd immunity scenario where, as long as most of the people in one area are vaccinated, the chances of something like measles entering and spreading in that community remain slim. But if you have a community—like Marin County in California where almost 18% of children were under-vaccinated between 2010–2012—in which a great number of school-going children are unvaccinated, the risk exponentially increases as more kids can catch the disease.
Dr. Tracy Lieu, who led this study, hopes that by zeroing in on the areas where there are clusters of unvaccinated children they can provide "focused intervention" to ward off future outbreaks. As she shared with the Los Angeles Times, "To the extent that we can identify these hot spots early on, it may help us to identify emerging epidemics sooner."
As of this weekend, the measles outbreak had affected 51 people, most of whom had not been fully immunized.