A talk by Professor Gareth Williams on 10 March 2026. Report by Stan Morrissey.
The story of the discovery of a successful treatment against smallpox that we heard from Gareth Williams turned out to be more curious and convoluted than simply a fortuitous finding by a country doctor.
Smallpox was once the deadliest disease known to mankind. The lifetime risk of catching it was 1 in 3, and it killed 1 in 12, nine tenths of whom were under five years of age. Many of those who survived were badly scarred for life. At a time when medicine was more magic than science, attempts at cures even as late as the Victorian period relied on bloodletting and leeches.
One misconception is that Edward Jenner invented inoculation. Eighty years before his experiments, Lady Mary Wortley Montagu, a well-travelled diplomats’ wife, encountered a technique in Istanbul that she termed variolation. Samples of pus were taken from an infected person and scratched into the skin of a healthy person to induce an infection, hopefully mild, that conferred protection; however, until the illness cleared up the patient was infectious, something not always understood. Lady Mary introduced variolation to England, where clinics were set up in many areas.
Jenner encountered variolation as a seven year old at boarding school in Wotton-under-Edge. The entire school was treated, though English doctors insisted the children were unnecessarily purged and blood-let as well, extending a process that should take a few seconds to several painful weeks. Jenner was left with a lifelong morbid fear of variolation.
When he started to practise medicine – at the tender age of sixteen – he came across the belief that milkmaids who had contracted cowpox from their charges were generally immune to smallpox. A John Fewster had set up a variolation clinic at Buckover and noticed that some people did not react; on investigation he found that they had all been exposed to cowpox. Jenner learned of this through a mutual colleague.
When Jenner went to London to complete his training he met John Hunter, a polymath with wide interests, such as how lizard’s tails regenerated when cut off, how the charge in electric eels was generated and how some people, apparently dead, came back to life. Jenner became his star pupil, sharing Hunter’s fascination with the natural world.
Jenner became a gentleman’s doctor in Berkeley, a bon viveur, musician and very poor poet. He experimented in many areas but often didn’t finish what he started. He kept in touch with Hunter throughout his life, who prompted him to investigate such matters as the core temperature of hibernating hedgehogs and the dissection of dolphins. Jenner was elected a fellow of the Royal Society, not because of his medical work but as the result of his investigations into how cuckoo chicks cleared their host’s nest of other chicks.
Despite Hunter’s urging it took Jenner several decades to get around to testing his theories about cowpox and smallpox. In May 1796 – in what we would today regard as a serious breach of medical ethics but was then deemed acceptable – he treated James Phipps, the eight year old son of his gardener, with cowpox pus taken from a milkmaid, Sarah Nelmes. He then gave him smallpox pus and, there being no reaction, declared him immune.
He submitted a paper to the Royal Society, which rejected it, so in 1798 he republished it as a pamphlet, explaining how it was done. This caused a sensation and it was presented at the Medical Society in London as being safer and more effective than variolation. News spread. King Carlos IV of Spain read a French translation and sent it to the Spanish colonies. By the time Jenner died in 1823 smallpox vaccination had been hailed worldwide as a major success and enthusiastically adopted in many countries.
In 1914 an American doctor proclaimed that “We have forgotten what smallpox is like” but this was decidedly premature for many other parts of the world. Though by 1967 north America, Europe, Russia and China were claimed free of smallpox, in Africa, India and South America it was still prevalent. A world-wide smallpox eradication programme was initiated. Rather than vaccinating everyone, an impossible task, countries looked for early signs of outbreaks and everyone in that area was vaccinated, preventing its spread. In 1977 the last victim in the world was infected but recovered. Ironically, he was a volunteer vaccinator who had not been vaccinated himself. In May 1980 smallpox was officially declared eradicated.
It is clear that Jenner was not alone in his efforts, and his methods were far from scientific, but they worked – and that’s what counts in the end!
For more about Edward Jenner, a visit to the Jenner Museum in Berkeley is strongly recommended.