On Immunity : An Inoculation (9781555973278) (5 page)

What vaccines do not cause, the report explained, is significantly harder to establish than what they do cause. While a substantial amount of evidence is acceptable as proof that an event does and can happen, there is never enough evidence to prove that an event cannot happen. Even so, the evidence reviewed by the committee “favors rejection” of the theory that the MMR vaccine causes autism. This report was released shortly after a national survey revealed that a quarter of the parents who responded believed that vaccines cause autism. And over half of the parents expressed concern about serious side effects from vaccines.

“Perceptions of risk—the intuitive judgments that people make about the hazards of their world,” the historian Michael Willrich observes, “can be stubbornly resistant to the evidence of experts.” We do not tend to be afraid of the things that are most likely to harm us. We drive around in cars, a lot. We drink alcohol, we ride bicycles, we sit too much. And we harbor anxiety about things that, statistically speaking, pose us little danger. We fear sharks, while mosquitoes are, in terms of sheer numbers of lives lost, probably the most dangerous creature on earth.

“Do people know which risks lead to many deaths and which risks lead to few?” the legal scholar Cass Sunstein asks. “They do not. In fact, they make huge blunders.” Sunstein draws this observation from the work of Paul Slovic, author of
The Perception
of Risk.
In a study that invited people to compare various causes of death, Slovic found that people tended to believe that accidents cause more deaths than disease and that homicide causes more deaths than suicide, when the opposite is true in both cases. In another study, people significantly overestimated the fatality rates of highly publicized or dramatic dangers like cancer or tornadoes.

One could interpret this, as Sunstein does, to mean that most people are just wrong about risk. But risk perception may not be about quantifiable risk so much as it is about immeasurable fear. Our fears are informed by history and economics, by social power and stigma, by myths and nightmares. And as with other strongly held beliefs, our fears are dear to us. When we encounter information that contradicts our beliefs, as Slovic found in one of his studies, we tend to doubt the information, not ourselves.

Bicycles, the
New York Times
reports, “are involved in more accidents than any other consumer product, but beds rank a close second.” This does not alarm me, though I am a frequent user of both beds and bicycles. I carry my son on the back of my bicycle and allow him to sleep in my bed, despite public service posters of a baby sleeping with a butcher knife that warn me, “Your baby sleeping with you can be just as dangerous.” The disregard for statistical risk that researchers observe in people like me may be at least partly due to an unwillingness to live lives dictated by danger. We sleep with our babies because the benefits, as we see them, outweigh the risks. The birth of my son, which posed a greater risk to my health than I anticipated when I became pregnant, gave me a new appreciation for the idea that there are some risks worth taking. “Having children,” a friend with grown children reminds me, “is the greatest risk you can take.”

“Perhaps what matters,” Sunstein muses, “is not whether people are right on the facts, but whether they are frightened.” And people do seem to be frightened. We are locking our doors and pulling our children out of public school and buying guns and ritually sanitizing our hands to allay a wide range of fears, most of which are essentially fears of other people. All the while we are also, in our way, reckless. We get
intoxicated
, from the Latin “to poison,” for fun. This contradiction leads Sunstein to worry that regulatory laws based on the priorities of the general public maybe prone to a pattern of “paranoia and neglect.” Too much attention may be spent on minimal risks, while too little is paid to pressing threats.

Paranoia, the theorist Eve Sedgwick observes, tends to be contagious. She calls it a “strong theory,” meaning a wide-ranging, reductive theory that displaces other ways of thinking. And paranoia very frequently passes for intelligence. As Sedgwick observes, “to theorize out of anything
but
a paranoid critical stance has come to seem naïve, pious, or complaisant.” She does not believe that paranoid thinking is necessarily delusional or wrong, but only that there is value to approaches that are less rooted in suspicion. “Paranoia,” Sedgwick writes, “knows some things well and others poorly.”

Intuitive toxicology
is the term that Slovic uses for the way most people assess the risk of chemicals. His research reveals that this approach is distinct from the methods used by toxicologists, and that it tends to produce different results. For toxicologists, “the dose makes the poison.” Any substance can be toxic in excess. Water, for instance, is lethal to humans in very high doses, and overhydration killed a runner in the 2002 Boston Marathon. But most people prefer to think of substances as either safe or dangerous, regardless of the dose. And we extend this thinking to exposure, in that we regard any exposure to chemicals, no matter how brief or limited, as harmful.

In exploring this thinking, Slovic suggests that people who are not toxicologists may apply a “law of contagion” to toxicity. Just as brief exposure to a microscopic virus can result in lifelong disease, we assume that exposure to any amount of a harmful chemical will permanently contaminate our bodies. “Being contaminated,” Slovic observes, “clearly has an all-or-none quality to it—like being alive or pregnant.”

Fear of contamination rests on the belief, widespread in our culture as in others, that something can impart its essence to us on contact. We are forever polluted, as we see it, by contact with a pollutant. And the pollutants we have come to fear most are the products of our own hands. Though toxicologists tend to disagree with this, many people regard natural chemicals as inherently less harmful than man-made chemicals. We seem to believe, against all evidence, that nature is entirely benevolent.

O
NE OF THE APPEALS OF ALTERNATIVE MEDICINE is that it offers not just an alternative philosophy or an alternative treatment but also an alternative language. If we feel polluted, we are offered a “cleanse.” If we feel inadequate, lacking, we are offered a “supplement.” If we fear toxins, we are offered “detoxification.” If we fear that we are rusting with age, physically oxidizing, we are reassured with “antioxidants.” These are metaphors that address our base anxieties. And what the language of alternative medicine understands is that when we feel bad we want something unambiguously good.

Most of the pharmaceuticals available to us are at least as bad as they are good. My father has the habit of saying, “There are very few perfect therapies in medicine.” True as it may be, the idea that our medicine is as flawed as we are is not comforting. And when comfort is what we want, one of the most powerful tonics alternative medicine offers is the word
natural.
This word implies a medicine untroubled by human limitations, contrived wholly by nature or God or perhaps intelligent design. What
natural
has come to mean to us in the context of medicine is
pure
and
safe
and
benign.
But the use of
natural
as a synonym for
good
is almost certainly a product of our profound alienation from the natural world.

“Obviously,” the naturalist Wendell Berry writes, “the more artificial a human environment becomes, the more the word ‘natural’ becomes a term of value.” If, he argues, “we see the human and the natural economies as necessarily opposite or opposed, we subscribe to the very opposition that threatens to destroy them both. The wild and the domestic now often seem isolated values, estranged from one another. And yet these are not exclusive polarities like good and evil. There can be continuity between them, and there must be.”

Allowing children to develop immunity to contagious diseases “naturally,” without vaccination, is appealing to some of us. Much of that appeal depends on the belief that vaccines are inherently unnatural. But vaccines are of that liminal place between humans and nature—a mowed field, Berry might suggest, edged by woods. Vaccination is a kind of domestication of a wild thing, in that it involves our ability to harness a virus and break it like a horse, but its action depends on the natural response of the body to the effects of that once-wild thing.

The antibodies that generate immunity following vaccination are manufactured in the human body, not in factories. “In the pharmaceutical world,” the writer Jane Smith observes, “the great division is between biologicals and chemicals—drugs that are made from living substances and drugs that are made from chemical compounds.” Using ingredients sourced from organisms, once living or still alive, vaccines invite the immune system to produce its own protection. The live viruses in vaccines are weakened, sometimes by having been passed through the bodies of animals, so that they cannot infect a healthy person. The most unnatural aspect of vaccination is that it does not, when all goes well, introduce disease or produce illness.

Infectious disease is one of the primary mechanisms of natural immunity. Whether we are sick or healthy, disease is always passing through our bodies. “Probably we’re diseased all the time,” as one biologist puts it, “but we’re hardly ever ill.” It is only when disease manifests as illness that we see it as unnatural, in the “contrary to the ordinary course of nature” sense of the word. When a child’s fingers blacken on his hand from Hib disease, when tetanus locks a child’s jaw and stiffens her body, when a baby barks for breath from pertussis, when a child’s legs are twisted and shrunken with polio—then disease does not seem natural.

Before Christopher Columbus landed in the Bahamas, the epidemic diseases of Europe and Asia did not exist in the Americas. There was no smallpox, no hepatitis, no measles, no influenza. The bacteria that cause diphtheria, tuberculosis, cholera, typhus, and scarlet fever were all unknown in this hemisphere. “The first recorded epidemic, perhaps due to swine flu, was in 1493,” Charles Mann writes in his book
1493.
From that year onward, earthworms and honeybees imported by Europeans would forever change the ecology of the Americas, cattle and apple trees would transform its landscape, and novel diseases would decimate its people. Within the next two hundred years, three-quarters or more of the native population of the Americas would die of disease. Considering this course of events “natural” favors the perspective of the people who subsequently colonized the land, but it fails to satisfy the “not made or caused by humankind” definition of the term. While the ecosystem of the Americas can never be restored to its pre-Columbian state, our efforts to limit epidemic diseases through vaccination may be one small measure of habitat restoration.

“The history of the recent centuries has its black passages—the slaughter of the buffalo on the western plains, the massacre of the shorebirds by the market gunners, the near-extermination of the egrets for their plumage,” Rachel Carson wrote in
Silent Spring.
She was writing in the late fifties, at a moment of acute atomic awareness, and the next of these black passages would be, she warned, a “new kind of fallout.” The pesticides and herbicides of postwar industry, some of them originally developed for war, were being sprayed from airplanes over acres of fields and forests. One of these, DDT, was making its way into groundwater, accumulating in fish, and killing birds. Over fifty years later, DDT persists in the bodies of fish and birds all over the world, as well as in the milk of nursing mothers.

The publication of
Silent Spring
in 1962 led to the creation of the Environmental Protection Agency and a ban on the production of DDT in this country. The book popularized the idea that human health depends on the health of the ecosystem as a whole, but Carson did not use the word
ecosystem.
She preferred the metaphor of an “intricate web of life,” in which a disturbance anywhere on the web sends tremors across the entire web. “
Silent Spring,”
Carson’s biographer Linda Lear writes, “proved that our bodies are not boundaries.”

Our bodies are not boundaries, but DDT is not exactly what Carson feared it was. DDT, she warned, was a widespread cause of cancer. This hypothesis was not supported by the decades of research on DDT that followed the publication of
Silent Spring.
Numerous studies on factory and farm workers with high DDT exposure failed to find an association between DDT and cancer. And studies of specific cancers found no evidence that DDT increased the incidence of breast cancer, lung cancer, testicular cancer, liver cancer, or prostate cancer. I mention this to my father, an oncologist, and he recalls the DDT sprayed all over his town from trucks when he was young. He and his siblings were kept inside during the spraying, but they ran out to play as soon as the trucks had passed, when the leaves of trees were still dripping DDT and the smell of the chemical was in the air. It does not bother him that Carson may have overstated some of the dangers of DDT, and that she got some things wrong, because, as he says, “she got the job done.” She woke us up.

“Few books have done more to change the world,” the journalist Tina Rosenberg acknowledges. “DDT killed bald eagles because of its persistence in the environment,” she writes. “
Silent Spring
is now killing African children because of its persistence in the public mind.” The blame for this may belong more to us, the inheritors of
Silent Spring
, than to the book, but either way malaria has resurged in some countries where DDT is no longer used against mosquitoes. One African child in twenty now dies from malaria, and more are left brain damaged by the disease. Ineffective treatments, toxic prophylactics, and environmentally damaging insecticides all remain in use because there is no viable vaccine against malaria.

For now, DDT is, unfortunately, one of the more effective means of controlling malaria in some places. Applied to the interior walls of homes once a year, DDT has nearly eliminated malaria in parts of South Africa. Compared to spraying DDT across millions of acres from airplanes, as was done in the United States, the environmental impact of this application is relatively small. But DDT remains an imperfect solution. Few chemical companies produce it, donors are unwilling to finance it, and many countries are reluctant to use a chemical that is banned elsewhere. “Probably the worst thing that ever happened to malaria in poor nations,” Rosenberg writes, “was its eradication in rich ones.”

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