The excellent Jason Crawford at the Roots of Progress has a long-form read on the history of smallpox eradication. It’s an important and insightful piece especially because Jason is interested not just in what happened but why it happened when and where it did and what the lessons are for today:
In 1720, inoculation had been a folk practice in many parts of the world for hundreds of years, but smallpox was still endemic almost everywhere. The disease had existed for at least 1,400 and probably over 3,000 years. Just over 250 years later—it was gone.
Why did it take so long, and how did it then happen so fast? Why wasn’t inoculation practiced more widely in China, India, or the Middle East, when it had been known there for centuries? Why, when it reached the West, did it spread faster and wider than ever before—enough to significantly reduce and ultimately eliminate the disease?
The same questions apply to many other technologies. China famously had the compass, gunpowder, and cast iron all before the West, but it was Europe that charted the oceans, blasted tunnels through mountains, and created the Industrial Revolution. In smallpox we see the same pattern. [Why?]
- The idea of progress. In Europe by 1700 there was a widespread belief, the legacy of Bacon, that useful knowledge could be discovered that would lead to improvements in life. People were on the lookout for such knowledge and improvements and were eager to discover and communicate them. Those who advocated for inoculation in 1720s England did so in part on the grounds of a general idea of progress in medicine, and they pointed to recent advances, such as using Cinchona bark (quinine) to treat malaria, as evidence that such progress was possible. The idea of medical progress drove the Suttons to make incremental improvements to inoculation, Watson to run his clinical trial, and Jenner to perfect his vaccine.
- Secularism/humanism. To believe in progress requires believing in human agency and caring about human life (in this world, not the next). Although England learned about inoculation from the Ottoman Empire, it was reported that Muslims there avoided the practice because it interfered with divine providence—the same argument Reverend Massey used. In that sermon, Massey said in his conclusion, “Let them Inoculate, and be Inoculated, whose Hope is only in, and for this Life!” A primary concern with salvation of the immortal soul precludes concerns of the flesh. Fortunately, Christianity had by then absorbed enough of the Enlightenment that other moral leaders, such as Cotton Mather, could give a humanistic opinion on inoculation.
- Communication. In China, variolation may have been introduced as early as the 10th century AD, but it was a secret rite until the 16th century, when it became more publicly documented. In contrast, in 18th-century Europe, part of the Baconian program was the dissemination of useful knowledge, and there were networks and institutions expressly for that purpose. The Royal Society acted as an information hub, taking in interesting reports and broadcasting the most important ones. Prestige and acclaim came to those who announced useful discoveries, so the mechanism of social credit broke secrets open, rather than burying them. Similar communication networks spread the knowledge of cowpox to from Fewster to Jenner, and gave Jenner a channel to broadcast his vaccination experiments.
- Science. I’m not sure how inoculation was viewed globally, but it was controversial in the West, so it was probably controversial elsewhere as well. The West, however, had the scientific method. We didn’t just argue, we got the data, and the case was ultimately proved by the numbers. If people didn’t believe it at first, they had to a century later, when the effects of vaccination showed up in national mortality statistics. The method of meticulous, systematic observation and record-keeping also helped the Suttons improve inoculation methods, Haygarth discover his Rules of Prevention, and Fewster and Jenner learn the effects of cowpox. The germ theory, developed several decades after Jenner, could only have helped, putting to rest “miasma” theories and dispelling any idea that one could prevent contagious diseases through diet and fresh air.
- Capitalism. Inoculation was a business, which motivated inoculators to make their services widely available. The practice required little skill, and it was not licensed, so there was plenty of competition, which drove down prices and sent inoculators searching for new markets. The Suttons applied good business sense to inoculation, opening multiple houses and then an international franchise. They provided their services to both rich and poor by charging higher prices for better room and board during the multiple weeks of quarantine: everyone got the same medical procedure, but the rich paid more for comfort and convenience, an excellent example of price differentiation without compromising the quality of health care. Business means advertising, and advertising at its best is a form of education, helping people throughout the countryside learn about the benefits of inoculation and how easy and painless it could be.
- The momentum of progress. The Industrial Revolution was a massive feedback loop: progress begets progress; science, technology, infrastructure, and surplus all reinforce each other. By the 20th century, it’s clear how much progress against smallpox depended on previous progress, both specific technologies and the general environment. Think of Leslie Collier, in a lab at the Lister Institute, performing a series of experiments to determine the best means of preserving vaccines—and how the solution he found, freeze-drying, was an advanced technology, only developed decades before, which itself depended on the science of chemistry and on technologies such as refrigeration. Or consider the WHO eradication effort: electronic communication networks let doctors be alerted of new cases almost immediately; airplanes and motor vehicles got them and their supplies to the site of an epidemic, often within hours; mass manufacturing allowed cheap production at scale of needles and vaccines; refrigeration and freeze-drying allowed vaccines to be preserved for storage and transport; and all of it was guided by the science of infectious diseases—which itself was by that time supported by advanced techniques from X-ray crystallography to electron microscopes.