[A] significant minority of parents — often well-educated parents — are opting out of vaccination. Many states (including California) make it relatively easy to refuse vaccination for “philosophic” reasons. This does not, I suspect, mean that people are reading Immanuel Kant or John Stuart Mill; it means they are consuming dodgy sources on the Internet.
Resistance to vaccination on the left often reflects an obsession with purity. Vaccines are placed in the same mental category as genetically modified organisms (GMOs), DDT and gluten. But the problem with organic health care is that the “natural” rate of child mortality is unacceptably high. Organically raised children can get some very nasty diseases.
Opposition to vaccination on the right often reflects an obsession with liberty — in this case, freedom from intrusive state mandates. It has always struck me as odd that a parent would defend his or her children with a gun but leave them vulnerable to a microbe. Some conservatives get especially exercised when vaccination has anything to do with sex — as with the human papillomavirus (HPV) vaccine — on the questionable theory that teenagers are more likely to fornicate if they have a medical permission slip (or less likely to without it).
Whether hipsters or home-schoolers, parents who don’t vaccinate are free riders. Their children benefit from herd immunity without assuming the very small risk of adverse reaction to vaccination. It is a game that works — until too many play it.
Herd immunity requires about 90 percent vaccine coverage. Some children with highly vulnerable immune systems — say, those being treated for leukemia — can’t be vaccinated for medical reasons. When the number of non-medical exemptions from vaccination gets large enough, the child with leukemia becomes the most vulnerable to the spread of disease.
The government (in this case, state governments) has the responsibility to keep vaccination rates above 90 percent, which benefits everyone. This requires burdening the freedom of parents in a variety of ways — not putting them in jail if they refuse to vaccinate but instead denying them some public good (such as public education) and subjecting them to stigma (which they generally deserve). As the rate of vaccination goes lower, the level of coercion must increase — making exemptions more difficult and burdensome to secure (as California needs to do).