The ox-faced boy who stared out from the opening page of Dr William Rowley’s pamphlet possessed strangely elongated eyes, one bloodshot and one healthy. His right cheek was reddish, while the entire left side of his face was so massively swollen that it knocked the contours of the boy’s healthy features off kilter. Several pages later, a portrait of the Mange Girl, a child of perhaps four years of age, looks out pitifully to readers, the skin from her cheek to her hip covered with clusters of painful-looking sores. The conditions of these children — and (supposedly) of thousands of others across Britain — were not, the accompanying literature warned, symptoms of any natural human ailment. Rather, they were the results of the recently developed smallpox vaccine, which Rowley said exposed recipients to “the diseases of beasts, filthy in their very nature and appearance, in the face, eyes, ears, with blindness and deafness, spreading their baneful influence over the whole body”.¹

Rowley was a prominent figure in nineteenth-century England’s anti-vaccine movement, the earliest predecessor to today’s anti-vaxxers. Several years before Rowley published his vitriolic pamphlet, Edward Jenner’s discovery of a vaccine against smallpox had caused a public health revolution and birthed the field of immunology as a discipline — but it also came decades before germ theory was known to scientists. As a result, even those who embraced Jenner’s vaccine lacked the conceptual framework needed to understand precisely how it worked. This gap between evidence and explanation allowed doubts to suppurate and spread as clergy, members of parliament, workers, and even doctors voiced their opposition to the vaccine on religious, ethical, and scientific grounds. Jenner’s supporters saw it as their moral duty to advance the cause of a life-saving technology; their opponents felt an equally strong moral obligation to put a halt to vaccination at all costs. In the decades following Jenner’s discovery, this conflict would play out bitterly in newspapers, in artwork, and even in the streets as both sides battled for the body and soul of Britain.

Living as we do at a time when the sudden emergence of a new virus has drastically altered the normal patterns of life, it can be difficult to imagine an environment where epidemic disease was the norm. Prior to the advent of vaccination, smallpox was widespread, deadly, and all but untreatable given the state of medical knowledge at the time. Roughly one third of those who contracted smallpox did not survive; those who did often bore grim reminders of the disease for the rest of their lives.² It could leave victims blind; it could reach down to their bones and render joints and limbs permanently deformed. And it left the vast majority of its victims’ faces scarred with the telltale pitted pockmarks, sometimes severely: historian Matthew L. Newsome Kerr estimates that “probably one-fourth to one-half of the population [of Britain] was visibly marked in some way by smallpox prior to 1800”.³

Folk wisdom, meanwhile, had long observed that those who worked closely with livestock possessed a strange resistance to the disease even as it ravaged the communities around them. Jenner, a country doctor, decided to put this idea to a formal test. In 1798, he lanced a sore on milkmaid Sarah Nelmes’ hand and injected the resultant lymph into the arm of his gardener’s son, James Phipps. A week later, Jenner exposed the boy to smallpox to see if he would get sick: as Jenner had hypothesized, the boy remained healthy. Just a year later, the first mass trials of the smallpox vaccine were already underway. (The preserved hide of Nelmes’ cow, Blossom, now resides in the library of St. George’s, a medical school in London.)

Jenner’s experiment had succeeded because the odd sores on Nelmes’ hand were symptoms of cowpox, a much less dangerous cousin of the smallpox virus that caused pustules on the hands but generally left its victims unharmed. The two pathogens were similar enough that exposure to cowpox effectively primed the body’s defenses against smallpox as well. Cowpox infections — and the immunity that came with them — were frequently transferred to dairy workers after they touched the udders of infected animals: indeed, the name Jenner chose for this therapy, vaccination, derives ultimately from the Latin word for cow (vacca). And crucially, as Jenner demonstrated, cowpox could also be transferred by lancing a human’s sores and injecting the fluid into another person — the so-called “arm to arm” method, which guaranteed a virtually inexhaustible supply of the vaccine even in urban areas far from the nearest dairy meadow.

But Jenner would not have been able to explain the workings of his discovery if asked: at the time, it was thought that smallpox was transmitted via poisoned air, or miasma, and the precise mechanisms of immune response were still unknown to science. As growing numbers of people embraced the vaccine, opposition began to coalesce. For these skeptics, the very notion of injecting a substance that ultimately derived from a diseased animal into a healthy human seemed not merely absurd but a serious peril to public health. Rowley’s scaremongering pamphlet warned that those who received the vaccine risked developing “evil, blotches, ulcers, and mortification”, among other “beastly” diseases.⁴ With the second edition of his pamphlet, a new illustration entered the menagerie of cowpox victims: Ann Davis, an elderly woman who upon receiving her dose had allegedly sprouted horns.

Others focused on the supposed cognitive effects of cowpox: Halket admitted that Rowley’s lurid accounts were perhaps far-fetched but nonetheless insisted that so-called “mental horns and cloven hoofs too frequently shoot out”, a metaphor for the “insurmountable stupidity [that] has been observed in some children from the time they were vaccinated, no symptom of which appeared prior to that time”.⁵ One of Jenner’s fiercest opponents, Benjamin Moseley, penned a tirade against the cowpox-derived vaccine in which he warned of its effects not only upon the body but also upon the mind:

        Who knows, besides, what ideas may rise, in the course of time, from a brutal fever having excited its incongruous impressions on the brain?
        Who knows, also, but that the human character may undergo strange mutations from quadrupedan sympathy; and that some modern Pasiphaë may rival the fables of old?⁶

Readers well versed in classics would have recognized this last line as a thinly veiled reference to bestiality: Pasiphaë, according to Greek myth, was the Cretan queen who gave birth to the Minotaur after having sex with a bull, driven to strange lust by a curse from Poseidon. Rowley plays with a similar innuendo in his pamphlet when he wonders whether receiving the vaccine could violate the biblical injunction against lying with an animal.⁷ Cowpox would go on to become tightly linked to syphilis (which in the past had often been referred to as “pox”) in the popular imagination, with rumors circulating that cattle contracted cowpox through contact with syphilitic milkmaids. These concerns were not allayed by the poor sanitation and medical standards that sometimes characterized the public vaccination hospitals created to serve Britain’s urban poor: at such places, the vaccines made available to patients often came not directly from cows but from the pustules of vaccinated children in the area, who may or may not have received a thorough medical check before being lanced for their “donation”. As a result, parents were not wholly unjustified in their fears that an injection meant to ward off one deadly disease might simply lead to their child being infected with another one.⁸

The satirist James Gillray channeled these popular anxieties about the monstrous aspects of the vaccine in his 1802 cartoon The Cow Pock—or—the Wonderful Effects of the New Inoculation! At the center, Jenner is seen delivering a rather vicious gouge to a woman’s arm with his lancet as all around her the previous vaccine recipients undergo horrible transformations: miniature cows erupt from boils and climb out of mouths, while women sprout horns and give birth to calves on the spot. That same year, Charles Williams published an anti-vaccine engraving in which doctors (all of whom have sprouted tails and horns) are arrayed before the maw of a cow-like monster covered in suppurating pustules. A £10,000 check protruding from a back pocket identifies one of these chimerical doctors as Jenner, who had received a cash reward from the government in recognition of his contributions to medicine. Only now he is transformed from medic into mercenary, shoveling babies with his colleagues into the beast’s gaping jaws and waiting for them to be excreted with horns. In the distance, anti-vaccine doctors bearing the weapons of truth approach to do battle with the creature and the doctors who feed it.⁹

Particularly in the early days, some objected to the vaccine on religious grounds, arguing that vaccination was a hubristic attempt to evade divine punishment. Similar arguments had been made surrounding the earlier technique of variolation, in which healthy people were deliberately exposed to the smallpox virus with the goal of bringing on a mild case of the disease that would nevertheless confer immunity. In 1721, when the Massachusetts Bay Colony was struck by a severe smallpox outbreak, Puritan leaders fiercely debated (and ultimately decided in favor of) the permissibility of variolation, which the preacher Cotton Mather argued had been put into humankind’s hands by God. A century later, theological debates about preventative medicine raged on: “The Small Pox is a visitation from God”, Rowley wrote, “but the Cow Pox is produced by presumptuous man: the former was what heaven ordained, the latter is, perhaps, a daring violation of our holy religion”.¹⁰ “Methuselah and his antediluvian contemporaries were not vaccinated which fully accounts for their coming to such a sudden and untimely end”, Halket noted caustically.¹¹ “The Creator stamped on man the divine image, but Jenner placed on him the mark of the beast”.¹² Cartoonists frequently depicted the cowpox-derived vaccine as a golden calf that would be the downfall of modern society at the hands of those who foolishly embraced its worship.

But while skepticism towards the vaccine was present from the beginning, the vitriol of the attacks against the cowpox method and its proponents would vastly expand in the mid-1800s, when parliament passed multiple laws making vaccination compulsory, providing free vaccination for the poor, and creating a system of punishments for those who failed to get the shot. These new measures made the question of vaccination impossible to ignore — and many saw such laws as an unacceptable abrogation of their personal liberties by the state.¹³ In popular writing, vaccines were compared to tattoos or brands (particularly owing to the scar left by the injection), and those who resisted getting them histrionically compared themselves to fugitive slaves. Across Britain, anti-vaccination societies organized mutual aid funds to defray the fines incurred by their members for refusing to vaccinate their children; if working-class vaccine objectors had their property seized as punishment, sympathizers would loudly protest at the auction, sometimes even assaulting the auctioneer. Contemporary newspapers described effigies of Jenner or public vaccine authorities being burned; in Leicester, a hotbed of resistance to the cowpox method, an anti-vaccine carnival drew as many as 100,000 demonstrators and prompted a parliamentary commission to review the vaccination laws.¹⁴

But proponents of using cowpox didn’t take all of this sitting down. As many were quick to point out, a number of the leading voices in the anti-vaccination movement had a major financial interest in stopping Jenner’s discovery from catching on. Indeed, both Moseley and Rowley had previously practiced variolation, which prior to Jenner had been considered the best way to prevent a serious case of smallpox. But the technique was riskier than vaccination — both to the patient and to those around them, who were likely to get infected by the convalescing patient. Once among the most common medical procedures in Britain, variolation was under serious threat from its new competitor even before parliament banned it completely in the mid-1800s.¹⁵ As such, when doctors like Moseley were penning screeds against the smallpox vaccine, they weren’t just trying to defend their readers — they were also trying to defend their stream of income.

Precisely this point was made by Isaac Cruikshank in an 1808 satirical print that depicts Jenner and his colleagues banishing variolators from the land. The latter group, hefting massive bloody knives over their shoulders, openly proclaim their desire to spread the disease further as they walk past the corpses of smallpox victims. At the far right of the cartoon, a milkmaid pipes up: “Surley [sic] the disorder of the cow is preferable to that of the ass.”

Jenner himself would make similar accusations when he decided to defend his ideas and his honor in print, pseudonymously publishing a rebuttal to Rowley, the cover of which was emblazoned with its own version of the ox-faced boy. Jenner’s words for those who attack the cowpox method in order to protect their own financial interests are scathing; nevertheless, he writes, “I trust that the good sense of the people of England will feel the injury, and know how to repel it as they ought”.¹⁶ Two hundred years later, however, attempts to discredit the safety and reliability of vaccination — whether against measles or against COVID — persist. The arguments made by today’s anti-vaxxers often echo those put forth by their nineteenth-century antecedents: claims of inefficacy, allegations of ghastly side effects, appeals to religion. Jenner seems likely to have assumed that the benefits of vaccination would be so self-evident that they would shut down all debate. That many continue to assail the safety and reliability of the method he pioneered, not only decades but centuries later, is something that, in all likelihood, the doctor never could have imagined.