Edward Jenner (1749–1823) was a British general physician who practiced in Berkeley, England. He had survived variolation as a child and was thus immune to smallpox. He was very learned, writing papers on medical matters, such as heart disease, as well as papers on natural history, such as how a newborn cuckoo bird was able to push his nest mates out of the nest. His most famous research, though, was on the prevention of smallpox by vaccination.
In rural Berkeley, where Jenner practiced, it was common knowledge that individuals who had experienced cowpox were protected from acquiring smallpox. Cowpox was a mild disease that caused blisters on a cow’s teats. It could be spread to humans and was usually acquired by people when milking cows. Jenner postulated that if he were able to expose a person to cowpox, he could introduce this milder disease, which would then protect the individual from the more deadly smallpox.
Using his knowledge of variolation, on May 14, 1796, Jenner removed pus from the cowpox blister of a young woman, Sarah Nelmes. He then spread the pus over cuts in the skin of an eight-year-old boy, James Phipps, who had never had smallpox or cowpox. James developed a mild case of cowpox a week later and recovered uneventfully.
Six weeks later Jenner exposed James to the pus from a blister on a smallpox patient in the normal manner of variolation. James did not develop smallpox on this or subsequent exposures. The experiment had worked; introducing the cowpox illness could provide protection from subsequent smallpox exposure. Jenner named the process vaccination, which is derived from the Latin word vacca, meaning “cow.”
Jenner reported this case and thirteen others to the Royal Society at the end of 1796. The medical establishment, as cautious as ever, was hesitant to accept the findings and recommended that he not publish his reports because it might injure his reputation. In 1798, Jenner published, at his own expense, a small book based on his case reports of his successful experiments on twenty-three people. The rather grand title of this publication was 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 Cowpox.
Over the next several years, Jenner perfected his method of vaccination. He found a way to dry the material from a cowpox lesion so that it would not lose its effectiveness. By storing the dried material in a glass container, people were able to transmit the material around the world. By 1810, communities were being vaccinated with Jenner’s dried cowpox lesions in Europe, India, and the newly formed United States of America.
It took over forty years for the medical community to fully embrace Jenner’s findings. However, over time, it was clear that his method of vaccination was superior to variolation because of the lower risk of illness and death. In 1840, variolation was banned in Great Britain, and the vaccine was provided free of charge to those who wished it. In 1853, the smallpox vaccine was made mandatory by the age of three months, or the family would be fined. The era of compulsory vaccinations had begun.
Even though Jenner is appropriately credited with publishing the first paper on using cowpox to prevent smallpox, there were several other individuals who performed the procedure before Jenner. For example, Benjamin Jesty, a farmer from Dorset, England, inoculated his wife and children using cowpox in
1774, over twenty years before Jenner’s experiment. Unfortunately, Jesty’s wife developed a severe infection from the scratches introduced on her arm during the transmission of the cowpox pus and nearly died. While Jesty did inoculate some other relatives and neighbors, he did not widely disseminate the information, leaving it to Jenner to receive the credit.