Edward Jenner

Edward Jenner the English physician and scientist (1749-1823), often called the father of immunology, who pioneered the smallpox vaccine and demonstrated in 1796 that inoculation with cowpox could protect against the far more lethal disease. His method of vaccination eventually led to the worldwide eradication of smallpox.

Early Life and Education

Edward Jenner was born on 17 May 1749 in Berkeley, Gloucestershire, the son of a clergyman. He was orphaned at an early age and raised by an older brother, and he showed an early interest in nature and natural history. He was apprenticed to a surgeon in Sodbury and then went to London to study under the surgeon John Hunter, whose empirical and experimental approach shaped his own methods. He also received a sound training in anatomy and midwifery, and he was a capable physician as well as a naturalist.

Hunter became a lifelong mentor and friend, encouraging Jenner to combine careful observation with experiment. Jenner returned to Berkeley to practise as a country doctor and naturalist, pursuing his medical work alongside studies of geology and of animal behaviour. He was a keen and precise observer, and it was this habit that prepared him for the discovery that made his name. His early paper on the nesting habits of the cuckoo, which showed that the young bird pushes its foster siblings from the nest, demonstrated the patience and accuracy of his method.

Smallpox and the Cowpox Observation

Smallpox was among the most terrible diseases of the eighteenth century, killing a large fraction of those infected and disfiguring many survivors. A practice known as variolation, deliberately inoculating a patient with material from a mild case, was used to confer immunity, but it carried a real risk of death and of spreading the disease. Jenner sought a safer method, and he reasoned that a disease of cattle that produced only a mild illness in humans might confer protection without the dangers of variolation.

He had often heard it said among the dairy folk of Gloucestershire that milkmaids who had caught cowpox, a mild disease of cattle, never afterwards took smallpox. On 14 May 1796 he tested the belief decisively, inoculating an eight-year-old boy named James Phipps with matter from the cowpox sores of a milkmaid. When the boy was later exposed to smallpox, he did not become ill. Jenner repeated the procedure on other subjects and confirmed that the protection could be renewed by further inoculations.

Publication and the Spread of Vaccination

Jenner submitted a paper describing his findings to the Royal Society, but it was returned for lack of convincing evidence. He therefore published his results at his own expense in 1798 as An Inquiry into the Causes and Effects of the Variolae Vaccinae, setting out several further cases and naming the procedure vaccination, from the Latin for cow. The Inquiry went through several editions and was soon translated into Latin, French and German.

The book provoked controversy, and some satire and opposition greeted the new practice, but the evidence was compelling and the method spread rapidly. Vaccination was adopted in Britain and across Europe and America, and Jenner devoted much of the rest of his life to promoting it and to supplying vaccine matter to those who requested it, often without charge. He also predicted that vaccination could, if pursued universally, one day extinguish smallpox altogether.

Later Years and Recognition

Jenner continued to practise medicine in Berkeley and to pursue his natural history interests. In 1821 he was appointed physician extraordinary to King George IV, and he received honours from several learned societies. He died of a stroke at his home on 26 January 1823 and was buried in the church at Berkeley. He had spent his final years preparing further observations on vaccination and campaigning against its misuse by careless practitioners, and he corresponded with physicians abroad who sought his advice on the practice.

His work was carried forward by others who refined the techniques of vaccination and extended them to the control of other diseases, but the principle he had established, that a mild infection can confer protection against a deadly one, remained the foundation of immunology. The word he coined, vaccination, passed into every language. The vaccine lymph he distributed helped to establish chains of transmission that allowed the practice to be sustained across continents, and his method was soon carried to the Americas and to Asia by physicians who recognised its value.

Influence and Legacy

The method introduced by Jenner made possible the organised campaigns that eventually eliminated smallpox, declared eradicated by the World Health Organization in 1980. It is estimated to have saved many millions of lives over the following two centuries and stands as one of the greatest achievements in the history of medicine. The global eradication campaign, completed after a decade of intensive effort, was the direct descendant of his single experiment in a Gloucestershire garden.

Jenner's habit of testing a popular belief by controlled observation also set an example for experimental medicine. His discovery that immunity could be induced with a related but harmless organism pointed the way toward the vaccines against rabies, cholera and many other diseases developed in the nineteenth and twentieth centuries. Louis Pasteur honoured him by extending the term vaccine to all preparations of this kind, and he is remembered as the founder of a science that has done more than almost any other to reduce human suffering.

See also

• Smallpox
• Vaccination
• Variolation
• Immunology