An Inquiry Into the Causes and Effects of the Variolae Vaccinae

"I’ve always loved reading original sources, or at least dipping into them. Their warmth and accessibility is often surprising. Try reading the first page of Darwin’s Origin of Species, for example: ‘My work is now nearly finished; but as my health is far from strong, I have been urged to publish this Abstract.’ Jenner’s book on cowpox vaccination to prevent smallpox, which he self-published in 1798, is no less engaging. ‘The Wolf, disarmed of his ferocity, is now pillowed in the lady’s lap. The cat, the little Tyger of our island whose natural home is the forest, is equally domesticated and caressed.’ The point he is making relates to how animal viruses pass readily to humans, especially cowpox, of course. Jenner’s book was revolutionary and caused an uproar among its readers, especially members of the establishment. The same, of course, was true for Darwin’s great work some sixty years later. Jenner’s choice to self-publish was a brave one, but he did not feel confident that the learned scholars of the Royal Society would agree to publish his controversial findings. The book is organised around 23 case histories that together support his historic insight into the protective power of cowpox against the most feared disease in human history, smallpox. His study also demonstrates that the protective vaccine can be transferred from the arm of one child to another in an extended series of vaccinations. Much of the writing is preoccupied with Jenner’s mistaken belief in an infection of horses as the origin of cowpox. But the important message remains loud and clear. Like many of the greatest stories, the essential cast of characters is small: Sarah Nelmes, the milkmaid who scratched her hand on a thorn and let the cowpox in; James Phipps, the gardener’s boy; Hannah Excell, age eleven; Mary Pead, age five; Mary James, age six; Robert Jenner, age eleven months; and the other members of the small band of children Jenner immunised to protect them against smallpox. This question provides a timely balance for our enthusiastic response to COVID-19 vaccines. Edward Jenner’s vaccine was highly effective but it still took more than a century and a half to end smallpox. The spread of vaccination across the globe is often cast as a glorious enterprise of vaccine voyages and dedicated pioneers paying out the chains of vaccination arm to arm, casting a net of vaccination across the globe. But to defeat smallpox, this global net had to be turned into something much more like a blanket. The problems faced by the smallpox eradication campaign were as diverse as the geography of the earth and the teeming humanity of its nations. In 1958 the World Health Assembly approved a resolution to eradicate smallpox and this resolution was intensified in 1966. Get the weekly Five Books newsletter In the first half of the twentieth century, Europe and North America experienced intermittent outbreaks of smallpox, first through endemic disease and later because of imported cases, especially as the Second World War was ending. The last epidemic in the United States occurred in 1949 in Elsa, Texas, and saw nine infections and one death. Intensive vaccination quickly put an end to the outbreak. By the middle of the twentieth century, Europe and North America were free of smallpox. South America followed in 1971 and global eradication efforts became focussed on Asia and Africa. The vaccine was still essentially Jennerian: calf lymph (or sheep or water buffalo) taken from pustules on the animals’ skin, with added stabilisers. But the campaign in tropical regions was now using freeze-dried vaccine—a huge step forward. Also instrumental in success was a simple forked applicator and later an automatic ‘jet’ injector delivering vaccine using high-pressure air. No needles were required for thousands of inoculations. But the final weapon essential to success was the ingenious use of ring vaccination or containment rather than mass vaccination. This focussed strategy was in large part due to the vision of William Foege, celebrated American vaccinator. Ali Maow Maalin of Somalia suffered the last natural case of smallpox in 1977 and went on to become a tireless vaccinator against polio. He was in the midst of this campaign when he contracted malaria and died in 2013."