Jenner , Edward

(1749–1823) British physician

Jenner, born a vicar's son at Berkeley in Gloucestershire, was apprenticed to the London surgeon John Hunter from 1770 to 1772. He then returned to country practice and established a reputation as a field naturalist. In 1787 Jenner observed that the newly hatched cuckoo, rather than the adult cuckoo, was responsible for removing the other eggs from the nest. He was elected a fellow of the Royal Society in 1789 partly on the basis of this work. Jenner's lasting contribution to science however is his investigations into the disease smallpox.

In 17th-century London some 10% of all deaths were due to smallpox. In response to this the practice of variolation – inoculation with material taken from fresh smallpox sores – was widely adopted. This was first described in England in 1713. However variolation suffered from two major defects for, if too virulent a dose was given, a lethal case of smallpox would develop and, secondly, the subject inoculated, unless isolated, was only too likely to start an epidemic among those in contact with him.

Jenner had heard reports that milkmaids once infected with cowpox developed a lifelong immunity to smallpox. On 14 May 1796, he made the crucial experiment and took an eight-year-old boy and injected him with cowpox. He followed this on 1 July with injections taken from smallpox pustules, repeating the procedure several months later. On both occasions the boy did not develop smallpox and the same happy result was later observed with other experimental subjects. Jenner's conclusion that cowpox infection protects people from smallpox infection was first published in An Inquiry into the Causes and Effects of the Variolae Vaccinae (1798).

General acceptance of Jenner's work was almost immediate. In 1802 he was awarded £10,000 by a grateful House of Commons and in 1804 he was honored by Napoleon who made vaccination compulsory in the French army. Variolation was made illegal in England in 1840 and in 1853 further legislation made the vaccination of infants compulsory. As a consequence of this deaths from smallpox, running at a rate of 40 per 10,000 at the beginning of the 19th century, fell to 1 in 10,000 by the end.