If you learned in school as I did that Edward Jenner invented immunization, you learned wrong. If you use an extremely narrow definition he probably invented vaccination but I’ll get back to that later.
Immunization by exposure to diseased persons or disease “material” goes back at least a millennium and is probably much older. There are attestations that the Chinese practiced “variolation”, a process by which smallpox scabs were blown up the noses of persons to prevent them from contracting the disease from at least as early as 1000 AD. By the 16th century the practice was widespread in the Far East, in India, throughout the Ottoman Empire, and in adjacent parts of Africa. Only Europe and the New World’s European colonies lagged behind and there is evidence that African slaves practiced variolation before their American masters did.
In 1717 Lady Mary Wortley Montagu, the wife of Edward Wortley Montagu, the British Ambassador to the Ottoman Empire, learned of the practice in Constantinople. When there was an outbreak of smallpox in London in 1721 Lady Montagu and the Princess of Wales engaged in an experiment in which they inserted smallpox “material”, i.e. scabs or pus, under the skin of prisoners and abandoned children and then exposed them to individuals with the disease. None contracted smallpox so it was deemed safe. It sometimes seems that medicine progresses one atrocity at a time.
In reality the fatality rate from variolation was about 3% compared with a fatality rate from smallpox contracted naturally of from 14% to 30%.
Edward Jenner was himself variolated and suffered from health repercussions from the treatment for the rest of his life. Jenner, apprenticed to a surgeon at 13, had noticed that milkmaids rarely contracted smallpox but frequently presented themselves for treatment for a similar but milder disease called “cowpox”. Farmers told him that cowpox prevented smallpox. In 1796 he inserted pus taken from a milkmaid’s cowpox lesion under the skin of his gardener’s young son and then exposed him to smallpox. He did not contract the disease. The material was called “vaccine” and the process by which it was administered “vaccination”, ultimately from the Latin, vacca, “cow”.
Vaccination proved so successful that it quickly spread through Europe and its colonies. In 1840 the British government banned variolation which had itself been known to produce smallpox outbreaks and made vaccination mandatory and free of charge.
In the 1870s Louis Pasteur, in working on chicken cholera, discovered that weakened versions of the pathogens worked as well as the fresh, live ones in producing immunization. Nowadays “killed” vaccines are much common than live ones. Pasteur developed vaccines for chicken cholera, rabies, and anthrax, just to name a few. He earned the enmity of physicians by a) being a chemist a b) urging them to wash their hands, something that remains a problem today.
Jonas Salk famously developed a vaccine for polio in 1954.
Today there are vaccines for hundreds of different diseases. When I was a kid vaccinations for diphtheria, tetanus, pertussis, and smallpox were compulsory. When I was in school the polio vaccine, too, became compulsory. I knew kids who had polio, something not nearly so common today and there’s little doubt that the successful vaccine is the explanation.
In Illinois today not only are the vaccines I was required to take required but also vaccines that weren’t available when I was a kid—measles, rubella, mumps, haemophilus influenzae type b, hepatitis type b, and chicken pox—are compulsory.
Immunization has never been without risks and has always been the subject of controversy. Recently, opposition to vaccination, popularized by celebrities, has probably resulted in new outbreaks of pertussis. I attribute it to ignorance of history, science and, particularly, statistics.
Note: in doing the research for this post I learned that in the 15th century medical treatises occasionally took the form of epic poems. Those were the days!