Who was Edward Jenner?
Edward Jenner (1749–1823) was the English country doctor who invented vaccination: on May 14, 1796, he inoculated 8-year-old James Phipps with cowpox and proved it protected against smallpox — launching the two-century campaign that eradicated the disease worldwide in 1980.
Last updated: October 2026
A country doctor in Berkeley, Gloucestershire, he had heard milkmaids say they would never get smallpox because they had caught the milder cowpox. He turned folk wisdom into tested science, publishing his results in 1798.
Edward Jenner was born in 1749 in Berkeley, a village in Gloucestershire in the west of England, where his father was the local vicar. He grew up in a world in which smallpox was an ever-present terror. The disease arrived without warning, covered its victims in pustules, killed roughly a third of those it infected, and left many survivors blind or scarred for life. In England, as across Europe, almost everyone met smallpox sooner or later, and parents who had watched one child die of it lived in dread of the next. There was no cure, and the only defence anyone had was a dangerous gamble called variolation.
Variolation, or inoculation, meant deliberately infecting a healthy person with matter taken from a smallpox pustule, usually through a scratch in the skin, in the hope that the resulting illness would be mild and leave lasting protection. It often worked, and it often did not. A significant minority of those variolated developed full smallpox and died, and they could infect others in the meantime. Yet the practice had powerful advocates. Lady Mary Wortley Montagu, the wife of the British ambassador to the Ottoman Empire, had seen variolation practised in Constantinople and campaigned for it in London in the 1720s, having her own children inoculated. By Jenner’s youth, variolation was widely used in England, and Jenner himself was variolated as a boy. He never forgot the ordeal, which was one reason he spent his life looking for something safer.
Jenner trained as a surgeon-apothecary, first apprenticed to a surgeon in nearby Sodbury, then in London under John Hunter, one of the great surgeons and anatomists of the age. Hunter became his mentor and lifelong friend, urging him to experiment and to trust observation over received opinion. Jenner returned to Berkeley to practise as a country doctor, a life of house calls, local patients, and modest fees, far from the medical establishment of London. He also pursued natural history, studying birds, and in 1789 he was elected a Fellow of the Royal Society for his work on the nesting behaviour of the cuckoo, showing that the young cuckoo pushes its host’s eggs out of the nest. It was the habit of a man who watched carefully and believed what he saw.
The observation that made Jenner famous came from the Gloucestershire countryside. Dairy workers, above all milkmaids, were known to catch cowpox, a mild disease of cattle that produced blisters on the hands of those who milked infected cows. Local folklore held that milkmaids who had caught cowpox never caught smallpox. Jenner heard the claim as a young apprentice and never let it go. He spent years testing it, collecting cases, and asking whether people who had had cowpox were truly protected. He found that the protection seemed real, but also that not every rash called cowpox was the same, and that some supposed cases offered no protection at all. The folklore was a clue, not an answer, and Jenner’s contribution was to turn it into a tested claim.
Jenner was not the first person to act on the idea. In 1774, a Dorset farmer named Benjamin Jesty inoculated his wife and two sons with cowpox matter, using a darning needle, and they escaped a later smallpox outbreak. Jesty never publicised his experiment, and it had no effect on medical practice. Others, including a German teacher and several country doctors, had similar intuitions. What set Jenner apart was that he tested the idea systematically, recorded the results, published them, and then campaigned for years to persuade the medical world to adopt the practice. Invention, in this case, meant proof and persuasion as much as the original idea.
The decisive case involved Sarah Nelmes, a milkmaid who had contracted cowpox from a cow called Blossom, and an eight-year-old boy named James Phipps, the son of Jenner’s gardener. On 14 May 1796, Jenner took matter from a cowpox pustule on Nelmes’s hand and inoculated Phipps with it, making two small scratches in the boy’s arm. Phipps developed a mild fever and a local reaction, then recovered. Weeks later, in July 1796, Jenner performed the harder test: he inoculated Phipps with matter from a smallpox pustule. If the cowpox had protected him, nothing would happen. Nothing did. Phipps showed no sign of smallpox, and the experiment, which would never pass a modern ethics committee, entered medical history.
Jenner repeated the experiment on other children, including his own son, and followed his subjects to check that the protection lasted. Then he wrote it up. In 1798 he published, at his own expense, a slim book with a long title: An Inquiry into the Causes and Effects of the Variolae Vaccinae, a Disease Discovered in Some of the Western Counties of England, Particularly Gloucestershire, and Known by the Name of the Cow Pox. The book set out his cases, his reasoning, and his claim that cowpox inoculation protected against smallpox. He called the new procedure vaccination, from vacca, the Latin word for cow.
The book was not an instant triumph. The Royal Society, which had elected him a Fellow for his cuckoo work, declined to publish his findings, and some London physicians dismissed the claims of a country doctor. Jenner answered by publishing further case reports and by sending vaccine material to doctors who were willing to try it. Within a few years, vaccination was being practised across Britain and Europe. Parliament, persuaded by the evidence, voted Jenner ten thousand pounds in 1802 and a further twenty thousand pounds in 1807, substantial sums that recognised a service to the nation. In 1803 the Royal Jennerian Society was founded to promote vaccination and to supply vaccine material.
Jenner’s method was not the one used today. He used live cowpox virus, and later doctors used a related virus, vaccinia, whose exact origins are still debated. The vaccine material was passed from child to child, arm to arm, in a chain that sometimes carried other infections with it. The technique was crude, and it improved enormously over the nineteenth century. But the principle was Jenner’s, and it was new: a mild, related disease could be used to train the body to resist a deadly one. That principle is the foundation of immunology.
Vaccination spread with remarkable speed for an age without modern communications. Doctors carried the vaccine in glass tubes, in dried threads, and in the arms of children who travelled as living carriers. The practice reached Europe, the Americas, and the European colonies within a few years of Jenner’s publication, and rulers across the continent ordered their armies and their populations vaccinated. Smallpox, which had killed kings and commoners alike, began to retreat from the countries that vaccinated systematically. The retreat was uneven, and it would take nearly two centuries to finish, but the direction was set in Jenner’s lifetime.
Jenner also discovered that vaccination was not a one-time announcement but a cause that needed defending. He answered critics, supplied vaccine to anyone who asked, and treated vaccination as a public good rather than a private patent. He refused to profit from the discovery, turning down opportunities to keep the technique secret or to sell it. When he died in Berkeley in 1823, he was a national figure, but he had spent much of his fortune on the campaign for vaccination and on the care of his patients.
Vaccination faced fierce opposition from the start. Some doctors doubted the evidence. Some clergy argued that deliberately introducing animal disease into the human body was unnatural or impious. Some members of the public, faced with a new medical procedure promoted by the state, resisted it as an intrusion. In 1802 the satirist James Gillray published a famous cartoon showing Jenner vaccinating patients who sprouted cow heads from their bodies, a joke that captured genuine public anxiety. Anti-vaccination movements, born in Jenner’s lifetime, have accompanied every vaccination campaign since.
Jenner’s later life was marked by personal loss. His wife Catherine died in 1815, and his eldest son died young. He continued to practise medicine in Berkeley, to advise on vaccination, and to correspond with doctors across the world. He also continued his natural history, and he never left the village where he had been born. He died of a stroke in 1823 and is buried in the churchyard at Berkeley, where his house and garden are preserved. A statue of Jenner stands in Kensington Gardens in London, and another in his native Gloucestershire.
Jenner’s principle outgrew his own disease. In the 1880s Louis Pasteur, honouring Jenner, used the word vaccination for his own vaccines against chicken cholera, anthrax, and rabies, extending the idea far beyond smallpox. The nineteenth and twentieth centuries produced vaccines against diphtheria, tetanus, typhoid, tuberculosis, polio, measles, and many other diseases, each one an application of Jenner’s insight that the body could be taught to defend itself. Vaccination became one of the great public health tools, and one of the most cost-effective interventions in the history of medicine.
Smallpox itself took longest. In 1967 the World Health Organization launched an intensified global campaign to eradicate the disease, using mass vaccination, surveillance, and the ring vaccination of contacts around each outbreak. The last known natural case occurred in Somalia in 1977, in a hospital cook named Ali Maow Maalin. In May 1980 the World Health Assembly declared smallpox eradicated, the first and so far the only human disease to be wiped from the earth by deliberate human action. The campaign’s success was a triumph of logistics and of the vaccine, and its starting point was a Gloucestershire milkmaid, a cow called Blossom, and a country doctor who believed what he saw.
Jenner is sometimes called the father of immunology, and the title is fair. He did not invent the idea that cowpox protected against smallpox, and he did not understand why it worked, since the germ theory of disease and the immune system were still a century away. What he did was harder: he tested a folk belief, proved it, published it, and persuaded the world to act on it. The modern vaccine, from the childhood immunisations given in every country to the vaccines developed in months during pandemics, descends from the two small scratches he made on a boy’s arm in May 1796.
This entry draws on Jenner’s own Inquiry into the Causes and Effects of the Variolae Vaccinae of 1798, the Encyclopaedia Britannica, the World Health Organization’s history of the smallpox eradication campaign, and the standard histories of vaccination and immunology. The dates of the Phipps experiment and of the eradication declaration are as given in those sources.