View source for Cowpox

===Discovery===
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.<ref>{{cite journal |last1=Plett |first1=Peter C. |last2=Schmidt |first2=J. G. |title=Peter Plett und die übrigen Entdecker der Kuhpockenimpfung vor Edward Jenner |trans-title=Peter Plett and other discoverers of cowpox vaccination before Edward Jenner |language=de |journal=Sudhoffs Archiv |date=2006 |volume=90 |issue=2 |pages=219–232 |jstor=20778029 |pmid=17338405 }}</ref> 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.<ref>{{cite journal | vauthors = Williams N | title = Pox precursors | journal = Current Biology | volume = 17 | issue = 5 | pages = R150–R151 | date = March 2007 | pmid = 17387780 | doi = 10.1016/j.cub.2007.02.024 | doi-access = free | bibcode = 2007CBio...17.R150W }}</ref>

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 [[cavalry|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 of Spain|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.<ref>{{Cite web | vauthors = Patowary K |date=2020-12-09 |title=Balmis Expedition - How Orphans Took The Smallpox Vaccine Around The World |url=https://www.amusingplanet.com/2020/12/balmis-expedition-how-orphans-took.html |access-date=2021-08-11 |website=Amusing Planet}}</ref>

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.<ref>{{cite book | vauthors = Tucker JB |title=Scourge: The Once and Future Threat of Smallpox |year=2001 |location=New York |publisher=Atlantic Monthly Press |page=[https://archive.org/details/scourgeoncefu00tuck/page/31 31] |isbn=978-0-87113-830-9 |url=https://archive.org/details/scourgeoncefu00tuck/page/31 }}</ref>

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 [[farrier]]s 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".<ref>{{cite journal | vauthors = Noyce RS, Lederman S, Evans DH | title = Construction of an infectious horsepox virus vaccine from chemically synthesized DNA fragments | journal = PLOS ONE | volume = 13 | issue = 1 | article-number = e0188453 | date = 2018-01-19 | pmid = 29351298 | pmc = 5774680 | doi = 10.1371/journal.pone.0188453 | doi-access = free | bibcode = 2018PLoSO..1388453N | veditors = Thiel V }}</ref>
Although cowpox originates on the udder of cows, Jenner took his sample from a milkmaid, Sarah Nelmes.<ref>{{cite web |author=<!-- not stated --> |date= |title=History of smallpox vaccination |url=https://www.who.int/news-room/spotlight/history-of-vaccination/history-of-smallpox-vaccination |website=who.int |location= |publisher=World Health Organization |access-date=July 4, 2025}}</ref>

Jenner extracted the pus of one of the lesions formed by cowpox on Nelmes to [[James Phipps]], an eight-year-old boy who had never had smallpox. 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. Jenner named this procedure "vaccination" from the Latin for cow, ''vacca''.<ref name=bynum >{{cite book |last1=Bynum |first1=W. F. |title=Science and the Practice of Medicine in the Nineteenth Century |date=1994 |publisher=Cambridge University Press |page=84 |isbn=978-0-521-27205-6 }}</ref>

The number of vaccinations among people of that era increased drastically. It was widely considered to be a relatively safer procedure compared to the [[variolation|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.{{citation needed|date=January 2023}}

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.{{citation needed|date=September 2025}}