Variolation had a long history in China, the Middle East and Africa. Its history in Britain was started by Lady Mary Wortley Montagu, one of the most colourful characters in immunology. She originally eloped with her husband, and then went with him to Constantinople where he was ambassador.

Wortley Montagu wrote extensively about Ottoman life, wore Turkish dress, visited harems and Turkish baths and disguised herself as a man in order to get into the Hagia Sophia mosque. While in Constantinople, she came across the practice of variolation and, in 1718, had her young son Edward variolated on the wrist with a “blunt and rusty needle”.

Returning to England she resumed life in society. She was a friend of the poet, Alexander Pope, who admired her intelligence and wit and was probably in love with her. In 1721 a smallpox epidemic was threatening Britain, and she persuaded Charles Maitland, her doctor in Constantinople, to variolate her daughter.

A royal interest

Wortley Montagu was a friend of Caroline, the Princess of Wales, who was also worried about the safety of her children. It’s thought that this was what prompted the interest of Britain’s royal family in variolation.

Sir Hans Sloane (later founder of the British Museum) organised “The Royal Experiment” in 1721, in which six condemned prisoners from Newgate Prison were variolated. They were then pardoned and released.

You might question several aspects of the ethics of this experiment. To see if this protected them from smallpox, Sloane paid for one of the pardoned female convicts to sleep in the same bed as a ten-year-old boy with smallpox for six weeks. Of course, nowadays this would raise safeguarding as well as ethical issues. As a result of the experiment, Princess Caroline arranged for orphan children in a local parish to be variolated, and, when these children also came to no harm, two of the royal princesses were treated.

This new procedure was very controversial. A proportion of those treated died as a result. It was argued from church pulpits that the practice was both dangerous and sinful as only God had the power to inflict disease. But, over the century, it became a relatively routine approach to protecting people from smallpox.

Development of vaccination

There was a belief in the countryside that people who looked after cows and had been infected with cowpox could not catch smallpox (milkmaids were said to have attractive non-pockmarked skin). In 1774, Benjamin Jesty deliberately infected his wife and sons with cowpox in an attempt to protect them from smallpox. What Jenner did was to take this a stage further, to vaccinate his patient with cowpox (the Latin word “vaccinus” means “from cows”), and then see if that stopped the symptoms that occurred after a person was variolated with smallpox.

So, in light of this story, was Jenner’s experiment on the Phipps unethical? Well, there are certainly things that we might question. Experimenting on the son of his gardener raises concerns about coercion and consent. We might question aspects of the scientific design given that there was only one subject. But to the central charge – that he deliberately exposed a young child to smallpox solely to see if his vaccination procedure was effective – I would argue that he is not guilty. What he did do was variolate the child, a standard medical treatment at the time, known to be effective against smallpox. Jenner routinely performed variolation on his patients, and had been variolated himself. He took advantage of this procedure to demonstrate that vaccination really did protect from smallpox – an experiment that changed our world.