Vaccine Refusal Is Like Drunken Driving
Should you get your kids vaccinated against measles? Of course you should.
You shouldn't do this, however, because it is risk-free. Drugs can have side effects, and although those documented for the MMR (measles, mumps and rubella) vaccine are either minor or extremely rare, the risk of something bad happening isn't zero. And although the belief in a link between the MMR vaccine and autism is a superstition foisted upon the world by a showboating British doctor who has since lost his medical license, there may well be links between the vaccine and other maladies that we just don’t know about yet.
Such is life. The medical consensus is always shifting; risk can't be completely eliminated. It’s just that, when you weigh the real and hypothetical risks of the MMR vaccine against the known risks posed by actual measles -- ear infections, pneumonia, convulsions, brain inflammation, brain damage, death -- they don’t amount to much.
For a long time, the risk of encountering measles in the U.S. didn’t amount to much either. Thanks to near-universal vaccination, measles and other once-deadly childhood diseases had become vanishingly rare. I met a pediatrician 15 years ago who had refused to let her kids go through the standard childhood vaccination cycle. She knew perfectly well that if lots of people followed her example it would be dangerous. But she also knew from her work as a doctor that everybody else in her community vaccinated their kids, so she figured hers were safe.
She was, in economic terms, a free rider -- taking advantage of a public good to which she didn't contribute. It was a terribly selfish choice, but it was also arguably a rational one. At least, it was back then.
Now, however, thanks to the rise of vaccine skepticism, the risk of encountering several of these childhood diseases in the U.S. has been growing, especially if you live in the hotbed of unconventional belief that is Southern California. In September, the Hollywood Reporter documented a whooping cough epidemic -- the worst since the 1940s -- in the affluent neighborhoods of West Los Angeles. This month, a measles epidemic centered on Disneyland has hit the region.
When these diseases run rampant, even those who have been vaccinated aren’t entirely safe. Vaccines succeed in large part because they make diseases so rare, not because everyone who gets one becomes completely immune. When vaccination rates fall, non-vaccinators not only expose their children to greater risk but they endanger lots of other people too, including people whose parents did choose to vaccinate them.
Every disease has a different “basic reproduction number,” or R0, a measure of how contagious it is. The formula to determine what percentage of the population needs to be vaccinated to stop a disease from spreading is 1 – 1/R0. For influenza, R0 is two or three, meaning that a vaccination rate of 50 percent might be enough to stop its spread. For the Ebola virus it could be as low as 1.5, meaning that only 33 percent would have to be vaccinated -- if there were a vaccine.
Measles is among the most infectious of diseases, with an R0 of between 12 and 18. At least 92 percent of the population has to be vaccinated to ensure that it doesn’t spread. The national MMR vaccination rate in the U.S. is, remarkably enough, 91.9 percent. There are communities, though, where the rate is much, much lower. Among the Ohio Amish, for example, who suffered the worst measles outbreak in decades last year, and also, as already noted, in certain nice neighborhoods in and around LA. Such clusters of the non-vaccinated give harbor to the disease and help it spread. And if polling results on vaccination beliefs by age hold up, we’re about to see a lot more such clusters as the millennials have kids.
This is what’s so problematic about yesterday’s assertions, made and then retracted by New Jersey Governor Chris Christie, and made and so far stuck to by Kentucky U.S. Senator Rand Paul, that vaccination should be a matter of parental choice. This view presumes that it’s a choice that affects no one outside your family. When you’re the only family in town choosing to forgo an MMR vaccine, that’s close to being true. As soon as vaccine-refusal begins to catch on, though, it not only increases the risk to your own children but begins to put others at risk as well. It becomes a choice along the lines of choosing to drive while drunk or go around the neighborhood setting houses on fire.
With drunken driving and arson, we all get that they are unacceptable. For one thing, there’s a direct, visible connection between the act and the damage it causes. It took a few decades to convince society on drunken driving, and even now lots of people still do it. But I’m pretty sure that Rand Paul wouldn't argue that anybody has a right to get hammered and then get behind the wheel.
With vaccinations, the culpability is more probabilistic, and we tend not to deal well with probabilities in public debates in the U.S. During the rise of vaccinations, most people had memories of the suffering that childhood diseases could wreak. Now those memories are gone, and it’s a matter of understanding percentages and trusting experimental data. Which means that Americans may have to get a lot more first-hand experience of measles epidemics before the vaccine skeptics (and their political enablers) catch a clue.
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