Edward Jenner

Edward Jenner was born on 17 May 1749 in Berkeley, Gloucestershire, the eighth of nine children. His father was the Reverend Stephen Jenner, vicar of Berkeley, and the family's standing ensured Edward received a solid early education at schools in Wotton-under-Edge and Cirencester. As a boy he underwent variolation — deliberate inoculation with smallpox material, then the standard method of building immunity — an experience that left a lasting mark on his health.

At thirteen, Jenner began a seven-year apprenticeship with Daniel Ludlow, a surgeon in Chipping Sodbury, acquiring most of the practical skills a surgeon needed. In 1770, aged twenty-one, he moved to London to train under the eminent surgeon John Hunter at St George's Hospital. Hunter passed on a piece of advice he attributed to William Harvey: 'Don't think; try.' The empirical spirit behind those words would shape Jenner's entire career. By 1773 he had returned to Berkeley, where he built a successful practice as a family doctor and surgeon, eventually earning an MD from the University of St Andrews in 1792.

Before Jenner became famous for vaccination, he earned his place in the scientific world through a meticulous study of the cuckoo. It was widely assumed that adult cuckoos evicted the eggs and chicks of their hosts, but Jenner demonstrated through direct observation, experiment, and dissection that it is the newly hatched cuckoo that does this work. He also identified the anatomical reason: the newborn cuckoo has a broad back with a pronounced hollow below the shoulder blades, perfectly shaped for levering eggs and nestlings over the rim of the nest. After about twelve days, this hollow fills in and disappears entirely.

Jenner published these findings in the Philosophical Transactions of the Royal Society in 1788, the same year he was elected a fellow of that body. His account was not universally accepted at first, but decades later the artist and bird observer Jemima Blackburn witnessed a blind nestling performing exactly the eviction Jenner had described, and her illustration was compelling enough to persuade Charles Darwin to revise a passage in a later edition of On the Origin of Species. Jenner's dual competence in animal biology and human medicine would prove directly relevant to his later work on vaccination, since the key insight — that a disease crossing from cattle to humans could confer protection — depended on understanding how diseases moved between species.

The popular story that Jenner was inspired by the clear complexions of milkmaids turns out to be a later invention by his biographer John Baron, not a documented fact. What Jenner actually did was more rigorous than a single charming observation. By 1796 he had formulated the hypothesis that the pus from cowpox blisters could protect a person from smallpox. On 14 May 1796 he tested this by taking material from blisters on the hands of a milkmaid named Sarah Nelmes, who had caught cowpox from a cow called Blossom, and inoculating it into James Phipps, the eight-year-old son of his gardener, through two small cuts in the boy's arm.

Phipps developed a mild fever but no serious illness. On 1 July 1796 Jenner then inoculated Phipps with variolous material — the standard smallpox immunisation method — and no disease followed. As the American physician Donald Hopkins later observed, Jenner's unique contribution was not simply using cowpox but proving through deliberate subsequent challenge that recipients were genuinely immune to smallpox, and showing that the protective material could be passed from person to person rather than needing to come directly from cattle each time. Jenner went on to test the procedure on twenty-three further subjects, including his own eleven-month-old son Robert, and published the full set of findings in 1798 in his Inquiry Into the Causes and Effects of the Variolae Vaccinae.

The medical establishment did not accept Jenner's findings immediately, but acceptance came. Parliament granted him ten thousand pounds in 1802 in recognition of his work, and a further twenty thousand pounds in 1807 after the Royal College of Physicians confirmed how widely effective vaccination had proved. In 1803 Jenner became president of the Jennerian Society, a body specifically created to promote vaccination and work toward eradicating smallpox. The British government eventually banned variolation outright in 1840 and provided cowpox vaccination free of charge.

The reach of the discovery extended far beyond Britain. Napoleon, despite being at war with Britain, had his entire French army vaccinated and awarded Jenner a medal. On two separate occasions Jenner personally petitioned Napoleon to release English prisoners of war, and Napoleon complied, reportedly saying he could not refuse anything to one of the greatest benefactors of mankind. Between 1803 and 1806 the Spanish Balmis Expedition carried the vaccine to the Americas, the Philippines, Macao, and China, vaccinating thousands. Jenner called it an example of philanthropy unmatched in the historical record.

Jenner never entirely left Berkeley, and the demands of promoting vaccination increasingly consumed time that had once gone to ordinary medical practice. He continued pursuing natural history alongside medicine; in 1823, the last year of his life, he presented a paper on bird migration to the Royal Society. That same year, on 25 January 1823, he was found in a state of apoplexy with his right side paralysed. He died the following day, 26 January 1823, aged seventy-three, from what appears to have been his second stroke, and was buried in the family vault at the Church of St Mary in Berkeley.

In 1821 he had been appointed physician extraordinary to King George IV and made both mayor of Berkeley and a justice of the peace. The World Health Organization declared smallpox eradicated in 1980, the direct long-term consequence of the vaccination programme Jenner started. In 2002 a BBC poll of the British public placed him among the 100 Greatest Britons. The terms vaccine and vaccination, now applied to immunisation against dozens of diseases, both derive from Variolae vaccinae, the Latin phrase Jenner himself coined, meaning pustules of the cow.