Edward Jenner

Edward Jenner (1749-1823), British doctor and naturalist, discoverer of the vaccine used to prevent smallpox who thereby helped establish a basis for the nascent practice of mass immunization as an important tool of public health.

Jenner was born on May 17, 1749, in Berkeley, Gloucestershire, in a rural vicarage, and became a keen observer of nature at an early age. After serving his surgeon’s apprenticeship (1761-1771), Jenner moved to London and studied anatomy and surgery with the prominent surgeon John Hunter. Hunter invited Jenner to be his assistant, working on the zoological material that Joseph Banks had brought back from the voyage of HMS Endeavour (1768-1771). Hunter remained Jenner’s mentor after he returned to Berkeley in 1773 and established his medical practice. Jenner forwarded specimens to London, and Hunter read his paper on the breeding habits of the cuckoo at the Royal Society. He was the first to write a thorough description of the behaviour of this parasitic bird. Observation and attention to detail helped Jenner transform folklore about milkmaids and cowpox into a practical and safe means of immunization against smallpox.

Smallpox inoculation, introduced into Britain by Lady Mary Wortley Montagu, and successfully used in particular by Dr Robert Sutton, was not without risk. Fatalities and the spread of the disease could follow inoculation, but smallpox had a particularly high incidence and killed or disfigured many. When inoculating patients as part of his medical practice, Jenner noticed, as others had, that some patients proved completely resistant, and there was no reaction following transfer of smallpox matter. Inquiry revealed that these patients had previously caught cowpox, which was a contagious disease of cattle with characteristic pustules, the matter from which easily transferred to those in close contact with cows such as milkmaids.

Medical men did not agree about the relationship between cowpox and smallpox and its possible preventative role. By the early 1780s, Jenner knew there were different kinds of cowpox and referred to that one apparently conferring immunity as “true cowpox”. Further work would convince Jenner that like Robert Sutton’s practice of using unripe pustules in smallpox inoculation, the matter from unripe cowpox pustules provided better protection. Jenner was a busy doctor and he made his observations on cowpox as and when the relatively infrequent cases arose. Jenner and Hunter continued to correspond and in 1796 Jenner was finally able to follow Hunter’s advice: “Why think? Why not try the experiment?”

On May 14, 1796, Jenner took cowpox matter from pustules on the arm of milkmaid Sarah Nelmes and inoculated it into the arm of an eight-year-old boy, James Phipps. Phipps quickly developed cowpox and recovered. On July 1 Jenner inoculated the boy with smallpox but he remained free from the disease. In 1798 Jenner published the results of 23 similar cases as An Inquiry into the Causes and Effects of the Variolae Vaccinae. He had taken the word “vaccine” from the Latin vacca for cow (he also used the word “virus”, but this should not be confused with the modern definition).

Jenner’s life was transformed—no more the quiet pursuit of medicine and natural history in rural England. He vaccinated, prepared dried material to send around the world in response to requests, corresponded, and wrote a series of pamphlets in defence of his procedure. Parliament voted Jenner £10,000 in 1802 and a further £20,000 in 1806 in recognition of his work. Napoleon struck a medal in his honour in 1804, but perhaps more significantly made vaccination compulsory for the French army in 1805. Jenner died at Berkeley on January 26, 1823.

Vaccination against smallpox remained the only preventative immunization until the work of Louis Pasteur in the second half of the 19th century opened up the field of medical microbiology and provided the means to produce vaccines against other diseases.