Ten states are battling the spread of measles, the contagious and sometimes lethal childhood disease once bested by vaccines. Washington state, in particular, has declared a state of emergency in response to the rising number of measles cases concentrated in Clark County, where childhood vaccination rates lag behind regional averages. Public-health officials have made special entreaties to residents to get themselves and their children vaccinated as the outbreak has spread.

But vaccinating after an outbreak has begun is suboptimal, to say the least; ideally, widespread vaccination should prevent flare-ups of disease from gaining traction in the first place. It’s understandable that, once parents start seeing and hearing of children they know falling ill, they might think twice about letting their own little ones go unvaccinated. But why the hesitation to begin with?

Medical anthropologist Elisa Sobo, who has researched families who choose not to vaccinate for philosophical reasons, recently told NPR that “most of the people who are hesitating to vaccinate. . . . They’re really smart people, and they’re highly, highly educated.” This tracks with other studies, which have found vaccine-phobic parents to be geographically clustered and on the college-educated, information-hungry side. They’re parents who are worried about safety and are mistrustful of medical authorities, and who have access to huge quantities of credible-seeming information suggesting that vaccines are not only unnecessary but also dangerous. Their actions, in other words, might seem to follow rationally from the knowledge they have.

In several ways, I’m primed to be a non-vaccinating parent: I’m a white urbanite living among other parents I know to either delay or refuse vaccinations. I tilt left, and I certainly understand doubts about pharmaceutical companies and government agencies. But my daughter is fully vaccinated in accordance with the Centers for Disease Control and Prevention’s immunization schedule, and so my other children will be.

I think it’s understandable that the resistance to drugs, as it were, among my set is coded as philosophical objection. Our society follows a contractual mythology, by which I mean we imagine many of our dealings with each other to correspond to a social covenant: I give up some of my freedoms for the guarantee of some of my rights, and you do the same — this is how we live together in peace. Thus, we describe our choices — political and otherwise — in terms of rationally maximizing personal benefits: I’ll agree to pay higher taxes only if I get something good in return, or I’ll follow traffic laws if everyone else does, too, meaning I trade my ability to get to work really quickly for a guarantee of my personal safety. We believe everyone acting in their own best interest will thus make society as a whole safer and more peaceful.

When it comes to vaccines, there are risks. Serious adverse reactions are extremely rare, but they happen. More common and less dangerous reactions, such as fainting post-vaccination and soreness or swelling at the injection site, are still distressing from a parental point of view. The hazy, far-down-the-line concern that some parents express — what if I vaccinate my child and years later she as a result develops some condition or symptom? — is based more on emotion than reason. But it can still feel like the wiser choice to opt out, since others are largely vaccinated and the diseases the vaccines protect against are mostly in the distant past or found in other countries.

But vaccination isn’t just about individual benefits. A belief in the common good requires individuals, at times, to take on risk for the benefit of the community as a whole. Even if you’re young and healthy and would likely survive measles, other people in the community aren’t and wouldn’t: Elderly people, immunocompromised people and infants, for instance, rely on you not to get sick — their lives depend on it. Widespread vaccination is not just beneficial for the vaccinated; it is especially critical for people who cannot be vaccinated, and our society doesn’t have much of a moral language for taking on personal risk for those reasons. But I think it’s a moral imperative nonetheless. By vaccinating yourself and your children, you help to create the “herd immunity” that protects the most vulnerable people in society from illness, injury and death. The lives you save, in other words, may not be your own.

And so we’re a vaccinating family. I often hear about letting children become immune to diseases “naturally” and avoiding the dangerous artifice of mainstream medicine. But I have a hard time taking that line of rhetoric to heart. I was born with — or otherwise acquired, it’s hard to know — epilepsy, meaning I will have seizures for the rest of my life. There is no cure, but I have been advised, over the years, of many natural remedies (biofeedback, meditation, valerian root, acupuncture, over-the-counter vitamins, special diets, etc.), and I have tried many of them. What works are prescription medications: boring, sterile, unnatural and effective. Nature is humorless, and its way of helping humankind is longsighted and cold: The weak die off. Mainstream medicine isn’t perfect, and it comes with its own hazards — but having seen the face of nature in my own bloody teeth, dazedly spit out post-seizure, I think it’s the best choice we have.

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