Free Denialism by Michael Specter

to look briefly like chipmunks, but occasionally infiltrating the linings of the brain and spinal cord, causing seizures, meningitis, and death).
    Even measles, an illness that most young parents have never encountered, infected nearly four million Americans annually until 1963, when a vaccine was introduced. Typically, hundreds died, and thousands would become disabled for life by a condition called measles encephalitis. (In parts of the developing world, where vaccines are often unavailable, measles remains an unbridled killer: in 2007, about two hundred thousand children died from the disease—more than twenty every hour.) In the United States, fifty-two million measles infections were prevented in the two decades after the vaccine was released. Without the vaccine, seventeen thousand people would have been left mentally retarded, and five thousand would have died. The economic impact has also been dramatic: each dollar spent on the MMR vaccine saves nearly twenty in direct medical costs. That’s just money; in human terms, the value of avoiding the disease altogether cannot be calculated. By 1979, vaccination had even banished smallpox, the world’s most lethal virus, which over centuries had wiped out billions of people, reshaping the demographic composition of the globe more profoundly than any war or revolution.
    Those vaccines, and others, have prevented unimaginable misery. But the misery is only unimaginable to Americans today because they no longer need to know such diseases exist. That permits people to focus on risks they do confront, like those associated with vaccination itself. Those risks are minute, and side effects are almost always minor—swelling, for instance; a fever or rash. Still, no medical treatment is certain to work every time. And serious adverse reactions do occur. If you hunt around the Internet for an hour (or ten) you might think that nobody pays attention to vaccine safety in America today. The Public Health Service has actually never been more vigilant. For example, in 1999 the Centers for Disease Control called for an end to the use of the oral polio vaccine, developed by Albert Sabin, which, because it contained weakened but live virus, triggered the disease in about ten people out of the millions who took it each year. (A newer injectable and inactivated version eliminates even this tiny threat.) Despite legitimate concerns about safety, every vaccine sold in the United States is scrutinized by at least one panel of outside advisers to the Food and Drug Administration before it can be licensed; many don’t even make it that far. As a result, vaccination for virtually every highly contagious disease is never as dangerous as contracting the infections those vaccines prevent.
    Prevention is invisible, though, and people fear what they cannot see. Nobody celebrates when they avoid an illness they never expected to get. Humans don’t think that way. Choosing to vaccinate an infant requires faith—in pharmaceutical companies, in public health officials, in doctors, and, above all, in science. These days, that kind of faith is hard to come by. So despite their success, there has been no more volatile subject in American medicine for the past decade than the safety of vaccines. There is a phrase used commonly in medicine: “true, true, and unrelated.” It is meant to remind physicians not to confuse coincidence with cause. That kind of skepticism, while a fundamental tenet of scientific research, is less easily understood by laymen.
    For most people, an anecdote drawn from their own lives will always carry more meaning than any statistic they might find buried in a government report. “Neither my husband nor anyone in his family has ever been vaccinated . . . and there isn’t a single person in his family who has ever had anything worse than a cold,” one woman wrote on the heavily read blog Mom Logic. “Myself and my family, on the other hand, were all vaccinated against every