Edward Jenner discovered the process of vaccination by observing that exposure to the rare disease of cowpox, even as a mere inoculation, made people immune to smallpox. He thereby established the practice of vaccination and in the process helped found the fields of virology and immunology. The number of lives saved by vaccination is incalculable.
Jenner was born on May 17, 1749, at Berkeley, in Gloucestershire, England. The son of the vicar of Berkeley, he was educated there until 1761 when, at the age of 13, he went to Sodbury to apprentice under a surgeon. He moved to London in 1770 to study anatomy and surgery as John Hunter’s first boarding student at St. George’s Hospital. He returned to Berkeley in 1773 to set up a medical practice and remained there the rest of his life.
Jenner first distinguished himself as a naturalist and bird-watcher, as the Royal Society published his observations of the cuckoo in 1788 and inducted him into its fellowship that year on the strength of this work. It was commonly known that cuckoos laid their eggs in the nests of hen hedge sparrows, who, it was believed, removed their own eggs to make room for the developing cuckoo. Jenner witnessed the young cuckoo heaving the hen hedge sparrow eggs out of the nest, thus revising the conventional wisdom.
Also in 1788, a smallpox epidemic plagued Gloucestershire, and local physicians responded by employing the variolation technique of inoculating the public with live smallpox taken from people suffering a mild case of the disease. This practice of scoring the arm veins of the healthy and exposing them to smallpox matter gathered from pustules on the affected was imported from Turkey in 1721 by Lady Mary Wortley Montagu, the wife of the British ambassador to the Ottoman Empire. The Dutch physiologist Jan Ingenhousz achieved much success with this method, but most physicians could not replicate his results, instead experiencing high mortality rates as patients developed not immunity but smallpox itself.
While performing such inoculations, Jenner noted that those who had survived cowpox did not fall prey to smallpox—in fact, they did not even suffer a mild attack of smallpox, as did others, in response to variolation. Jenner developed an hypothesis over his two decades of working with pox that cowpox inoculation (which did not render patients immune from cowpox) might inoculate patients against smallpox, and by 1796, he was ready to test his theory experimentally.
Jenner administered the cowpox inoculation to James Phipps, an eight-year-old patient: he made two small cuts in the boy’s arm and introduced a speck of cowpox. The usual reaction resulted, as Phipps experienced a slight fever a week later, from which he recovered promptly. Two months later, Jenner administered variolation, and Phipps remained completely healthy. Jenner concluded that cowpox inoculated against smallpox, and he named his procedure "vaccination" (from the Latin for cowpox, vaccinia).
Jenner reported his findings to the Royal Society, which advised him against publishing something "so much at variance with established knowledge." He disregarded this advice, choosing instead to privately publish a memoir in 1798 entitled 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 Cow Pox. The practice of vaccination spread throughout Europe—within two years, more than 100,000 people had been vaccinated. In 1802, Parliament awarded Jenner 10,000 pounds in recognition of the contribution his vaccination made to public health, and it granted him yet another 20,000 pounds five years later.
For his final contribution, Jenner returned to his interest in naturalism to write On the migration of birds, which he published the year of his death. Jenner died of a stroke at his birthplace on January 24 (or 26), 1823. After his death, vaccination continued to gather momentum, as the practice of variolation was outlawed in 1850, and in 1853, vaccination was made compulsory. However, this law was not enforced until 1872, when the smallpox death rate was 90 per million, down from 3,000 to 4,000 per million the previous century. Smallpox was eradicated in the 20th century and now exists only in vaccination form.
