Vaccines have worked so well they've made themselves seem unnecessary.
For as long as medicine has offered protection against infectious disease, a portion of humanity has refused it — not out of ignorance alone, but from deep wells of religious conviction, bodily autonomy, and the peculiar amnesia that follows suffering's end. MIT science writer Thomas Levenson traces this refusal back to 1798, when the first smallpox vaccine met immediate opposition, and finds that the arguments have scarcely changed in two centuries. His new book suggests that vaccine hesitancy is not a product of the digital age but a recurring feature of the human relationship with medical progress — one whose consequences, measured in rising measles cases and falling herd immunity, are once again becoming visible.
- Measles cases are climbing in the United States as vaccination rates slip below the 95% threshold needed to shield those who cannot protect themselves — infants, transplant patients, the immunocompromised.
- The very success of vaccines has become their liability: generations born after 1970 have no lived memory of polio wards or diphtheria wards, making the diseases feel like myths and the vaccines feel like unnecessary risks.
- Anti-vaccine arguments have proven remarkably elastic — shifting from religious objection to appeals to nature to claims of active harm, each reframing surviving the collapse of the last.
- Levenson documents that when real vaccine failures occurred historically, regulatory systems responded and improved — yet the anti-vaccine movement has learned to treat any medical risk, however small, as evidence of unique danger.
- The oldest tension in the debate — whether the state may require something be placed in a person's body for the collective good — remains philosophically unresolved even as its public health consequences grow more concrete.
Thomas Levenson, a science writer at MIT, set out to find the origins of vaccine skepticism and discovered they stretch back not to social media or the late 20th century, but to 1798 — the year Edward Jenner's smallpox vaccine first entered public use. Opposition arose almost immediately, and the arguments, Levenson found, have barely evolved since.
The earliest objections were theological: if God governed disease, human intervention seemed blasphemous. When science eroded that position, opponents reframed their case around nature — arguing that true immunity came from clean living, not needles. That language persists today. Claims of active harm are equally old. Early vaccination practice did produce real problems: contaminated batches, practitioners who mistook syphilis for cowpox, vaccines that didn't confer lifelong immunity. But Levenson's central point is that when genuine failures occurred, the medical system responded. A contaminated diphtheria antitoxin created the first U.S. regulatory body for biologics. A flawed polio vaccine batch in 1955 was pulled within two weeks and led to a strengthened FDA division. The anti-vaccine movement, he argues, has become adept at treating the ordinary risks of any medical intervention as evidence that vaccines are uniquely dangerous.
The deeper paradox is that vaccines worked so thoroughly they made themselves seem unnecessary. Life expectancy in the U.S. was 47 at the turn of the 20th century; it hovers near 80 today across the developed world. Anyone born after 1970 has no visceral memory of polio season — of children returning from birthday parties only to be paralyzed weeks later. That forgetting created space for a third strain of opposition: the political one. When Britain mandated smallpox vaccination in the mid-19th century, the immediate question was whether the state had any right to require something be placed in a person's body. Levenson believes it does, because societies are built on mutual dependence. But he understands the philosophical weight of the disagreement, even as he finds the underlying worldview — that one owes nothing to anyone — both lonely and dangerous.
Measles cases are now rising as coverage falls below the 95% threshold required for herd immunity, leaving infants, transplant recipients, and the elderly exposed. Levenson's book, 'A Pox on Fools,' is an argument that understanding the long history of vaccine hesitancy — its recurring patterns, its exploitation of real but rare failures — is the first step toward seeing past it. Vaccines, he concludes, have saved more lives than any other invention in human history. The arguments against them are old. So is the cost of believing them.
Thomas Levenson, a science writer at MIT, has spent years chasing a simple question: Where did vaccine skepticism come from? The answer, he discovered while researching his new book, is not from the internet age or the last few decades. It reaches back to 1798, when the first smallpox vaccine entered public use, and the arguments against it have barely changed in two centuries.
The opposition began almost immediately, rooted in a conviction that vaccination violated something sacred. In the early 1800s, when Edward Jenner's innovation used material from cowpox—a mild disease in cattle—to protect humans against smallpox, many people saw the practice as an affront to divine authority. If God controlled disease, then human intervention seemed blasphemous. When that argument lost ground to scientific evidence, opponents shifted their language. Vaccination became unnatural, a violation of the body's own order. This reframing proved durable. It still echoes today in arguments that align immunity with nature, exercise, and diet rather than needles and science.
The claim that vaccines actively harm people is equally old. Within years of the smallpox vaccine's introduction, stories circulated about its dangers. Some were fabrications. Others pointed to real problems in early vaccination practice. Around 750 people in Europe contracted syphilis after being vaccinated by practitioners who mistook syphilis infections for cowpox and transmitted the disease to healthy people. The early vaccines also did not confer lifelong immunity as people believed they would. But here is what Levenson emphasizes: when genuine problems emerged, the medical system fixed them. A contaminated diphtheria antitoxin at the turn of the 20th century led directly to the creation of the Division of Biological Controls, the first U.S. regulatory body for biologics. When one of five manufacturers of the polio vaccine produced a flawed batch in 1955—sickening thousands and killing about a hundred people—the vaccine was pulled from shelves within two weeks. The FDA vaccine division was strengthened as a result. The anti-vaccine movement, Levenson argues, has become skilled at exploiting the fact that any medical intervention carries some risk. A sore arm or a day of feeling unwell are the most common vaccine side effects. Hip replacement surgery, which Levenson had performed last year, carries the risk of surgical infection. Yet vaccines are treated as uniquely dangerous while other medical procedures are accepted as necessary trade-offs.
The deeper paradox is this: vaccines have worked so well that they have made themselves seem unnecessary. At the turn of the 20th century, life expectancy in the United States was 47 years, and infectious diseases were among the leading causes of death. Child mortality was high. Today, life expectancy hovers around 80 in every developed nation, and child mortality is a fraction of 1 percent. By 1970, vaccines had nearly eliminated what were once called childhood diseases. For anyone born after that year, measles, polio, and diphtheria are not lived experiences. They are historical abstractions. Levenson points out that in 1952, the largest polio outbreak in American history terrified parents. Children could attend a birthday party and return home with muscle aches and fever, only to be paralyzed or dead weeks later. Three years later, the Salk vaccine arrived. That fear vanished so completely that younger generations have no memory of it, no visceral understanding of what vaccination prevented.
This forgetting has opened space for a third strain of anti-vaccine argument: the political and philosophical one. In the mid-19th century, when the United Kingdom mandated smallpox vaccination for children, immediate opposition arose around a single question: Who has the right to require someone to put something in their body? John Simon, England's top doctor at the time, called the refusal to vaccinate one's children "omissional infanticide"—a choice to let children die by withholding protection. The tension remains unresolved. Levenson acknowledges the philosophical weight of the question. He believes the state does have the right to mandate vaccines for the common good, because we live in societies and depend on each other. But he understands those who disagree, even as he thinks they are wrong. What troubles him is the underlying worldview: the belief that one owes nothing to anyone and nothing owes anything to oneself. It is, he suggests, both lonely and fearful.
Today, measles cases are rising in the United States as vaccination coverage declines. The disease requires 95 percent of a population to be vaccinated to maintain herd immunity—the threshold that protects those who cannot be vaccinated: infants too young, transplant recipients on immunosuppressive drugs, the elderly whose immunity has waned. When coverage falls below that line, every newborn becomes vulnerable. Levenson's book, "A Pox on Fools: The True Believers, Grifters, and Cynics Who Convinced Us to Reject Vaccines," is an attempt to show that vaccine hesitancy is not a new phenomenon born of social media, but a recurring human response to medical innovation. Understanding its history, he hopes, might help people see through the noise and recognize a simple truth: vaccines have saved more lives than any other invention in human history.
Citas Notables
Vaccines are the greatest lifesaving invention humankind has ever come up with.— Thomas Levenson
We don't live in a world where these diseases are common anymore, and that forgetting has opened space for skepticism.— Thomas Levenson, paraphrased
La Conversación del Hearth Otra perspectiva de la historia
You trace vaccine skepticism back two hundred years. Why does that history matter now?
Because the arguments haven't changed. We think we're dealing with something new—social media, conspiracy theories—but the core objections are the same ones people made in 1800. Understanding that pattern helps you see what's actually happening beneath the noise.
What's the most persistent argument?
That vaccines violate something natural or sacred. It started as a religious objection—God controls disease, we shouldn't interfere. When science made that harder to defend, it became about aligning with nature instead. That argument is still winning because it feels true, even though it isn't.
You mention that vaccines have actually been harmful in some cases. Doesn't that validate skeptics?
It does, which is exactly why the anti-vaccine movement uses those stories. But here's what's crucial: when real problems emerged—syphilis transmission, contaminated batches—the system fixed them. The regulatory bodies we have now exist because of those failures. The movement treats any risk as disqualifying, but they don't apply that standard to anything else.
The book emphasizes that younger people have never lived with these diseases. Is that the real problem?
It's the deepest one. If you were born after 1970, you've never seen polio paralyze a child or measles kill. You have no reference point for what vaccination prevented. So a vaccine that causes a sore arm seems worse than a disease you've never witnessed. That's not stupidity—it's a failure of collective memory.
What do you say to someone who genuinely questions whether the state should mandate medical procedures?
That's a real question, and I don't dismiss it. But the answer depends on whether you believe we have obligations to each other. I do. We live in societies. We depend on each other. That creates duties. But I understand people who see it differently. I just think they're wrong.