Cowpox

In the years from 1770 to 1790, at least six people who had contact with a cow had independently tested the possibility of using the cowpox vaccine as an immunization for smallpox in humans. Among them were the English farmer Benjamin Jesty, in Dorset in 1774 and the German teacher Peter Plett in 1791.[9] Jesty inoculated his wife and two young sons with cowpox, in a successful effort to immunize them to smallpox, an epidemic of which had arisen in their town. His patients who had contracted and recovered from the similar but milder cowpox (mainly milkmaids), seemed to be immune not only to further cases of cowpox, but also to smallpox. By scratching the fluid from cowpox lesions into the skin of healthy individuals, he was able to immunize those people against smallpox.

Reportedly, farmers and people working regularly with cattle and horses were often spared during smallpox outbreaks. Investigations by the British Army in 1790 showed that horse-mounted troops were less infected by smallpox than infantry, due to probable exposure to the similar horsepox virus (Variola equina). By the early 19th century, more than 100,000 people in Great Britain had been vaccinated. The arm-to-arm method of transfer of the cowpox vaccine was also used to distribute Jenner's vaccine throughout the Spanish Empire. Spanish king Charles IV's daughter had been stricken with smallpox in 1798, and after she recovered, he arranged for the rest of his family to be vaccinated.

In 1803, the king, convinced of the benefits of the vaccine, ordered his personal physician Francis Xavier de Balmis, to deliver it to the Spanish dominions in North and South America. To maintain the vaccine in an available state during the voyage, the physician recruited 22 young boys who had never had cowpox or smallpox before, aged three to nine years, from the orphanages of Spain. During the trip across the Atlantic, de Balmis vaccinated the orphans in a living chain. Two children were vaccinated immediately before departure, and when cowpox pustules had appeared on their arms, material from these lesions was used to vaccinate two more children.[10]

In 1796, English medical practitioner Edward Jenner tested the theory that cowpox could protect someone from being infected by smallpox. There had long been speculation regarding the origins of Jenner's variolae vaccinae, until DNA sequencing data showed close similarities between horsepox and cowpox viruses. Jenner noted that farriers sometimes milked cows and that material from the equine disease could produce a vesicular disease in cows from which variolae vaccinae was derived. Contemporary accounts provide support for Jenner's speculation that the vaccine probably originated as an equine disease called "grease".[11] Although cowpox originates on the udder of cows, Jenner took his sample from a milkmaid, Sarah Nelmes.

Jenner extracted the pus of one of the lesions formed by cowpox on Nelmes to another individual who had never had smallpox, an eight-year-old boy called James Phipps. He eventually developed a scab and fever that was manageable. Approximately six weeks later, Jenner then introduced an active sample of the smallpox virus into Phipps to test the theory. After being observed for an extended amount of time, it was recorded that Phipps did not receive a reaction from it. Although Jenner was not the first person to conceive the notion of cowpox protecting against the smallpox virus, his experiment proved the theory. It was later discovered that the cowpox vaccination only worked temporarily against the invasion of smallpox and the procedure would need to be repeated several times through one's lifetime to remain smallpox free.

In later years, Jenner popularized the experiment, calling it a vaccination from the Latin for cow, vacca. The amount of vaccinations among people of that era increased drastically. It was widely considered to be a relatively safer procedure compared to the mainstream inoculation. Although Jenner was propelled into the spotlight from the vaccination popularity, he mainly focused on science behind why the cowpox allowed persons to not be infected by smallpox. The honour of the discovery of the vaccination is often attributed to Benjamin Jesty, but he was no scientist and did not repeat or publish his findings. He is considered to be the first to use cowpox as a vaccination, though the term vaccination was not invented yet.

During the midst of the smallpox outbreak, Jesty transferred pieces of cow udder which he knew had been infected with cowpox into the skin of his family members in the hopes of protecting them. Jesty did not publicize his findings, and Jenner, who performed his first inoculation 22 years later and publicized his findings, assumed credit. It is said that Jenner made this discovery by himself, possibly without knowing previous accounts 20 years earlier. Although Jesty may have been the first to discover it, Jenner made vaccination widely accessible and has therefore been credited for its invention.[12]

The majority of the population at the time accepted the up-and-coming vaccination. However, there were still opposition from individuals who were reluctant to change from the inoculations. In addition, there became a growing concern from parties who were worried about the unknown repercussions of infecting a human with an animal disease. One way individuals expressed their discontent was to draw comics that sometimes depicted small cows growing from the sites of vaccination. Others publicly advocated for the continuance of the inoculations; however, this was not because of their discontent for the vaccinations. Some of their reluctance had to do with an apprehensiveness for change. They had become so familiar with the process, outcome, positives, and negatives of inoculations that they did not want to be surprised by the outcome or effects of the vaccinations. Jenner soon eased their minds after extensive trials. However, others advocated against vaccinations for different reason. Because of the high price of inoculation, Jenner experienced very few common folk who were not willing to accept the vaccination. Due to this, Jenner found many subjects for his tests. He was able to publish his results in a pamphlet in 1798: An Inquiry into the Causes and Effects of Variolae Vaccinae, a Disease, Discovered in some of the Western Counties of England particularly Gloucestershire, and known by the Name of Cow Pox.[13] [14]

While the vaccination's popularity increased exponentially, so did its monetary value. This was realized by the British Parliament, which compensated Jenner 10,000 pounds for the vaccination. In addition, they later compensated Jenner an additional 20,000 pounds. In the coming years, Jenner continued advocacy for his vaccination over the still popular inoculation. Eventually, in 1840, the inoculation became banned in England and was replaced with the cowpox vaccination as the main medical solution to combat smallpox. The cowpox vaccination saved the British Army thousands of soldiers, by making them immune to the effects of smallpox in upcoming wars. The cowpox also saved the United Kingdom thousands of pounds.[17]

Kinepox is an alternative term for the smallpox vaccine used in early 19th-century America. Popularized by Jenner in the late 1790s, kinepox was a far safer method for inoculating people against smallpox than the previous method, variolation, which had a 3% fatality rate.

In a famous letter to Meriwether Lewis in 1803, Thomas Jefferson instructed the Lewis and Clark expedition to "carry with you some matter of the kine-pox; inform those of them with whom you may be, of its efficacy as a preservative from the smallpox; & encourage them in the use of it..."[18] Jefferson had developed an interest in protecting American Indians from smallpox, having been aware of epidemics along the Missouri River during the previous century. A year before his special instructions to Lewis, Jefferson had persuaded a visiting delegation of North American Indian chieftains to be vaccinated with kinepox during the winter of 1801–1802. Unfortunately, Lewis never got the opportunity to use kinepox during the pair's expedition, as it had become inadvertently inactive—a common occurrence in a time before vaccines were stabilized with preservatives such as glycerol or kept at refrigeration temperatures.