One of the weird things about the anti-vaccination movement in the United States is that though it is often perceived to be liberal, its political orientation is pretty mixed. Chris Mooney put up a long data filled post a few weeks ago detailing this, including citing some of my old posts looking at GSS data. In general what you see is that for many “anti-science” views the biggest correlate is being stupid, not being liberal or conservative. Basically the less intelligent/educated/wealthy are more suspicious of “book learning,” and that includes science.

But the perception that anti-vaccination sentiment is liberal isn’t coming out of thin air. The issue is that a small and motivated culturally prominent social sector on the Left is promoting this viewpoint, out of proportion to its numbers and policy heft. By the latter, I mean that the liberal political establishment arguably has less sympathy with anti-vaccination sentiment than some of the more conspiratorial Tea Party people on the Right (though I guess Robert Kennedy weighs against that point). Less tendentiously, anti-vaccination sentiment is just plain counter-cultural, and has little traction among the political elites. In California anti-vaccination sentiment as reflected in lower rates of inoculation seem correlated with affluent liberal enclaves. But I stumbled on a more shocking illustration. Number of Marin children without vaccinations continues to grow; health officials worried:

And the rate is much higher than that at some Marin schools. At The New Village School in Sausalito, 14 of the 19 students entering kindergarten in 2012-13, 74 percent, exercised the personal belief exemption. That same year at the Greenwood School in Mill Valley, 14 of 21 incoming kindergartners, 67 percent, used the personal belief exemption. And at San Geronimo Valley Elementary in 2012-13, 13 of 29 kindergartners, 45 percent, avoided vaccinations using the personal belief exemption. Officials at the schools declined to comment.

These are very small numbers. The overall rate of lack of vaccination for young people seems be 7 to 8 percent in the county as a whole (not trivial, since that’s the on the edge of what researchers feel is necessary for “herd immunity”). But I was curious about these schools. The Greenwood School has a tuition of $20,000 per year. New Village is $16,000 per year. San Geronimo Elementary seems to be a public school, but it is notable that the Wikipedia entry references the liberalism of the citizenry.

As I noted above if a large enough fraction of the population is vaccinated then that confers herd immunity. Assuming that 93 percent or more of the population is vaccinated is there any material benefit from avoiding vaccination? Obviously there is the issue with discomfort. My children screamed like the dickens when they were first vaccinated. But I do assume that there are rare cases when vaccination actually does cause problems. A friend of mine from when I was younger died of an allergic reaction to the Anthrax vaccine when he was being inducted into the military. Apparently a small number of deaths can be justified by the greater good in this case.