Category Archives: The history of vaccines

Variolation: Immunity to Smallpox



Lady Mary Wortley Montagu (1689–1762)

Small pox was one of the most common infectious diseases that killed thousands in recurring epidemics. It can be traced as far back as ancient Egypt and in various outbreaks it regularly killed off large numbers of people. By the 17th Century it had recurred in many societies. Thomas Sydenham believed that small pox was best understood as a disease of passage: once you got it and survived there was no chance of getting it again. We are startled at his equanimity because there were such high mortality rates. Apparently in the 17th seventeenth and throughout the eighteenth centuries, about 60% of the population got small pox and 20% died of it: death was a much greater spectre in daily life than it is today. One of the disadvantages of living in cities was that infectious diseases spread more quickly in them, and one of the advantages was that if you survived them your immunity increased. In the Americas and Australia after the arrival of Europeans, mainly small pox, but other diseases such as measles killed many millions of indigenous people who had had no previous contact and hence little immunity to the diseases. In some cases 90% of a particular population died.

Lady Mary Wortley Montagu was the wife of the British ambassador to the Ottoman Empire and saw how the Turks inoculated people to cause a mild form of smallpox and produce immunity to the disease. The procedure was called “variolation” and was performed by rubbing powdered small pox scabs on a superficial scratch, or injecting fluid from a small pox pustule. This method had ancient roots. Lady Wortley-Montagu contracted smallpox in 1715 and bore its scars. She had her son Edward variolated in Turkey and then when she returned to England and a smallpox epidemic started in 1721 she asked her doctor, Charles Maitland, to variolate her young daughter. Maitland tested the procedure by variolating six prisoners and infecting them with this mild version of smallpox. None of them later contracted small pox. We must assume that they were in one way or another exposed to it.

Variolation was taken up by royal families across Europe but it did not spread to the general public. Lady Mary is one of the very few women mentioned in most medical histories. But despite the introduction of variolation, there was still very little understanding of the nature of infectious diseases.  Variolation was not an entirely safe procedure because one did contract a mild version of small pox: about one in every hundred people who were variolated died of the disease – a much lower percentage than the 20% who died of small pox.