In 1780, University of Bologna physician Luigi Galvani found something peculiar: When he applied an electric current to the legs of a dead frog, they twitched. Thirty-seven years later, Mary Shelley had Galvani’s experiments in mind as she wrote her fable of Faustian overreach, wherein Dr. Victor Frankenstein plays God by reanimating flesh.

And a little less than halfway between those two dates, English physician Edward Jenner demonstrated the efficacy of a vaccine against smallpox—one of the greatest killers of the age. Given the suspicion with which Romantic thinkers like Shelley regarded scientific progress, it is no surprise that many at the time damned the procedure as against the natural order. But what is surprising is how that suspicion continues to endure, even after two centuries of spectacular successes for vaccination. This anti-vaccination stance—which now infects even the White House—demonstrates the immense harm that can be done by excessive distrust of technological advance.

In 1796, Jenner took pus from a cowpox pustule on the hand of an infected milkmaid and injected it into the arm of an 8-year-old boy. Cowpox was a relatively harmless disease that farmworkers often caught from their livestock. Jenner (among others) speculated that a case of cowpox protected against the far more deadly smallpox. To test his theory, the doctor repeatedly exposed his young subject to smallpox. The boy remained healthy.

Jenner’s report on his experiment, An Inquiry Into the Causes and Effects of the Variolae Vaccinae (Latin for “pustule of cows”), was published in 1798 and was an instant sensation. In 1802, the British Parliament awarded the physician 10,000 pounds for his contribution to the well-being of mankind. And it wasn’t just in Britain: Emperor Napoleon released British prisoners of war when Jenner requested, saying, “I can refuse him nothing.” The doctor himself predicted that vaccination might eventually lead to the complete eradication of smallpox.

But others were less sanguine about the impact of the new technology. In 1800, Benjamin Mosley of the Royal College of Physicians alluded to the story of the Minotaur—offspring of Queen Pasiphae and a Cretan Bull— warning “the human character may undergo strange mutations” thanks to exposure to cowpox. He suggested “some modern Pasiphae may rival the fables of old”—that vaccinated women might be driven to run madly in search of the nearest bull to copulate with. Soon enough, a different British doctor reported the birth of a “cow poxed ox-faced boy,” and the newly formed Anti-Vaccine Society published a cartoon titled “The Cow-Pock or the Wonderful Effects of the New Inoculation!” It featured miniature cows growing out of the arms, faces, and buttocks of the vaccinated. By the mid-19th century, the next generation of anti-vaxxers had a whole body of pseudoscience behind them, including faked and fraudulent statistics showing that vaccines failed to prevent smallpox—or even increased smallpox risk.

When governments began making vaccination compulsory, public opposition grew more vocal. Riots followed the British Vaccination Act of 1853, a law that fined or imprisoned parents who didn’t vaccinate their children against smallpox, and demonstrations went on for decades. Thirty-two years after the act became law, more than 100,000 people in Leicester still showed up to protest against it. By 1898, the British government relented under the pressure, allowing “conscientious objectors” to vaccines an exemption from the law. The early anti-vaxxer victory crossed the Atlantic. Compulsory vaccination laws that had passed in the second half of the 19th century were soon overturned or weakened in California, Illinois, Indiana, Minnesota, Utah, West Virginia, and Wisconsin.

Fear fuelled by pseudoscience didn’t stop vaccines from revolutionizing world health. Jenner’s prediction that his technique could eradicate smallpox came true in 1980—thanks in part to a vaccination effort spearheaded by the World Health Organization. It is the greatest victory against disease in human history: Hundreds of millions died of smallpox in the 20th century; none have died in the 21st. Beyond smallpox, the Centers for Disease Control and Prevention estimates that worldwide, vaccines against a growing assortment of infections prevent 2.5 million deaths of children under the age of 5 each year. That has helped reduce childhood mortality overall: In 1980, 12 out of every 100 children born died before their fifth birthday in 1980. It’s close to 4 out of every 100 today.

But despite these gains, every minute worldwide three children die from vaccine-preventable diseases. And one big reason for these deaths is lingering distrust of vaccination. In 1998, just shy of two centuries after Benjamin Mosley suggested vaccination could cause strange mutations, Andrew Wakefield—a fellow of the Royal College of Surgeons—published a paper linking measles, mumps, and rubella vaccination to autism. The findings were as fake as the warnings of cowpox-induced bestiality, and the journal that published them has since retracted Wakefield’s paper. But propelled by false information on anti-vaccination websites and comments from witless television personalities such as Jenny McCarthy and Donald Trump, the debunked theory spread—and managed to stir up a new generation of anti-vaccine campaigns around the globe.

A 2016 survey of attitudes toward vaccination across 67 countries found that 13 percent of respondents have some safety-related skepticism about vaccines. That number reaches as high as 45 percent in France. One in 5 Russians, meanwhile, simply doesn’t think vaccines work. In the United States, a survey by the Pew Research Center found that 16 percent of Americans either doubt or felt unsure about vaccine safety. Most skeptics, the findings noted, were from younger generations that weren’t alive when the country had widespread measles infections.

When vaccination fears make vaccination rates go down, illness returns. In Swansea in the United Kingdom, where one-third of children went unvaccinated against measles, more than 1,200 people were infected in a 2013 outbreak of the disease. More than 20,000 cases of measles occurred in France between 2008–11. Four-fifths of the sufferers were unvaccinated, and 10 people died. And in 2015 in the United States, 188 people from 24 states and the District of Columbia were infected. The history of vaccination demonstrates how suspicion left unchecked, despite centuries of evidence to the contrary, can have immense costs.

Scientific discoveries deserve critical reception. Some turn out to be simply wrong while others turn out to have dangerous or deadly consequences—from sharpened flints to fusion, many technologies can be used for harm. But there are also plenty of examples of important discoveries that provoked overblown fears. Take Galvani’s experiments with frogs’ legs. More than 200 years on, an undead apocalypse is still a concern for Hollywood, not the Defense Department. Instead galvanism led to life-saving interventions—the pacemaker and the defibrillator among them. Technological advances have left the world far richer and healthier than ever before. For all of the risks of scientific arrogance illustrated by Shelley’s Frankenstein, denying the power of technology for good has turned out to be even more harmful.

This article is part of the Frankenstein installment of Futurography, a series in which Future Tense introduces readers to the technologies that will define tomorrow. Each month, we’ll choose a new technology and break it down. Future Tense is a collaboration among Arizona State University, New America, and Slate.