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Rates of unvaccinated children in charter schools—and to a lesser extent private schools—far outweigh non-vaccination rates in public schools, according to new data compiled by University of Maryland sociologist Philip Cohen.

Cohen used California data for 7,000 schools, as well as state public health data for vaccine exemption rates for kindergartners for 2014-2015.  The state actually tracks these — they’re called  “Personal Belief Exemptions.”

“Some of them got supposedly got counseling before making the request, while others further requested a religious exemption from the counseling — those two groups are combined here in the PBE rate,” he writes.

He then weighted the analyses by the number of kindergartners enrolled in each school.


His main finding: “Runaway vaccine exemptions are problems of the private and charter schools.”

The average exemption rate for charter schools is 8.42 percent, and in private schools 5.12 percent. In public schools, they’re just 1.77 percent.


Meanwhile, 36 percent of charter school students are in schools where more than 5 percent of students have exemptions, and 30 percent of private school students are so. But just 11 percent of public school students attend such schools.


He also found that in general, lower vaccination rates are correlated with wealthier schools regardless of type.

“Rich charter schools on average have the highest exemption rates, while poor schools — charter or not — are heavily clustered around [exemption rates of] zero,” he writes.


Cohen says he has not put together data that would explain these correlations, but that there is a likely explanation.

“Because they are more parent-driven, or targeted at certain types of parents, charter schools are more ideologically homogeneous,” he writes. “And because anti-vaccine ideology is concentrated among richer parents, charter schools provide them with a fertile breeding ground in which to generate and transmit anti-vaccine ideas. That’s why, although richer parents in general are driving vaccine denial, it’s especially concentrated in charter schools.”


Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.