Discovery of Vaccination (1796)

Summary

On May 14, 1796, Edward Jenner inoculated eight-year-old James Phipps with cowpox matter taken from a dairymaid’s sore, then challenged the boy with variolous (smallpox) matter less than seven weeks later. No disease followed. Jenner’s Communication to the Royal Society was rejected; he published the Inquiry as a private pamphlet in 1798, proposing cowpox inoculation (vaccination) as a substitute for variolation. The experiment launched a practice that would eventually eradicate smallpox. However, Crookshank’s examination of Jenner’s private manuscripts and published accounts reveals that the evidentiary basis was remarkably thin: a single successful experiment with a short follow-up interval, prior practitioners who had independently used cowpox (notably Benjamin Jesty in 1774), contradictory results from horsepox cases, and at least one suppressed fatality. The heroic narrative of a lone discoverer masks a more complex history of folk knowledge, contested evidence, and priority disputes.

Background

Variolation Before Jenner

Smallpox inoculation (variolation) was practiced across Circassia, the Ottoman Empire, India, China, Africa, and the Americas before being introduced to England, with no single identifiable origin point. (Crookshank, Edgar M., 1889) Lady Mary Wortley Montagu introduced the Ottoman inoculation method to England after observing it in Adrianople in 1717; her daughter was inoculated in England in April 1721, the first openly performed British case. (Crookshank, Edgar M., 1889)

During the first eight years of inoculation in Britain (1721-1729), 897 persons were inoculated, 845 developed true variolous pustules, and 17 died — a mortality of approximately 1 in 53 — while natural smallpox killed about 1 in 6. (Crookshank, Edgar M., 1889) Dr. John Jurin used statistical analysis to conclude that natural smallpox killed 1 in 14 children, while inoculation killed only 1 in 91 — the first systematic statistical argument for a medical preventive procedure in Britain. (Crookshank, Edgar M., 1889)

Emanuel Timoni’s description (communicated to the Royal Society in 1714-16) of Turkish inoculation reported that of fifty inoculated persons none died, whereas natural smallpox killed about half of those infected. (Crookshank, Edgar M., 1889) In India, inoculation was performed annually by specialized Brahmin castes who used year-old variolous matter preserved on cotton pledgets, never fresh matter. (Crookshank, Edgar M., 1889)

In colonial Boston, Zabdiel Boylston inoculated 244 persons in 1721. Six died (attributed by Boylston to other causes), six showed no effect at all, and the practice still faced official censure from Boston authorities who judged it dangerous to public health. (Crookshank, Edgar M., 1889)

Religious and medical opposition to inoculation condemned it as atheism, quackery, and a practice derived from “ignorant women amongst an illiterate and unthinking people.” (Crookshank, Edgar M., 1889)

The Dairymaid Tradition

The tradition that cowpox conferred immunity to smallpox originated not with Jenner but with folk observation among dairymaids. It arose from the failure of variolous inoculation on persons who had recently contracted cowpox; in many parts of the country the tradition was unknown among those familiar with cowpox, because inoculation was not practiced everywhere. (Crookshank, Edgar M., 1889)

Mr. Nash (d. 1785) documented in unpublished papers circa 1781 that of approximately 60 persons who reported having had cowpox whom he tried to inoculate with variolous matter, about 40 could not be infected — the earliest known statistical record of cowpox immunity. (Crookshank, Edgar M., 1889) Crookshank argued that even in the 1880s, the actual frequency of cowpox in England was unknown because farmers systematically concealed outbreaks when they occurred, for obvious economic reasons, producing the false impression that the disease had become extinct in England. (Crookshank, Edgar M., 1889)

Prior Vaccinations

Benjamin Jesty, a farmer of Yetminster, Dorset, deliberately inoculated his wife and two sons with fresh cowpox matter from infected cows in spring 1774 — the earliest documented intentional vaccination, predating Jenner by 24 years. (Crookshank, Edgar M., 1889) The frontispiece of Crookshank’s own volume reproduces a portrait of Jesty taken at age seventy, identifying him as a farmer of Downshay, Isle of Purbeck, who inoculated from his own cows “at that Time disorder’d by the Cow Pock” and whose family was subsequently “found unsusceptible of the Small Pox” after rigorous trials. (Crookshank, Edgar M., 1889) Multiple independent practitioners in Dorset and Ireland documented intentional self-inoculation with cowpox before Jenner’s 1798 publication, including Robert Fooks (inoculated 1771). (Crookshank, Edgar M., 1889)

Jenner dismissed Jesty’s prior vaccination as a “trick” invented by George Pearson to deprive him of credit, while Baron’s biography of Jenner virtually ignored Jesty’s documented vaccinations. (Crookshank, Edgar M., 1889)

The Event

Jenner’s Formation

Jenner’s early experience of smallpox inoculation at age eight — six weeks of preparatory bleeding, purging, and low diet followed by confinement in a “terrible state of disease” in an inoculation stable — may have motivated his later work to replace variolation. (Crookshank, Edgar M., 1889) John Hunter mentored Jenner as a house pupil, and Jenner later communicated his observations to Hunter. (Crookshank, Edgar M., 1889)

Jenner’s 1780 conversation with Edward Gardner first articulated his theory that cowpox derived from horsepox (“the grease”), and his ambition to disseminate vaccination to the total extinction of smallpox — but he kept it private to avoid ridicule if experiments failed. (Crookshank, Edgar M., 1889)

The Rejected Manuscript

Jenner’s original manuscript for the Royal Society opened with the hypothesis that human infectious fevers arise from familiarization with animals, and specifically argued that horsepox transmitted to cows was the origin of cowpox. (Crookshank, Edgar M., 1889) The rejected paper presented only ten cowpox cases as evidence for immunity, selected specifically as instances where smallpox inoculation failed; no cases of successful re-inoculation after cowpox were included, and no allowance was made for individual insusceptibility. (Crookshank, Edgar M., 1889)

The Phipps Experiment

The first recorded deliberate vaccination experiment by Jenner was on May 14, 1796: he inoculated James Phipps, a healthy boy about eight years old, with cowpox matter from a dairymaid’s sore; the boy was mildly ill on days 7-9 and well on day 10. (Crookshank, Edgar M., 1889) The variolous challenge test was applied to Phipps less than seven weeks later (on July 1, 1796), and produced no disease. (Crookshank, Edgar M., 1889)

Crookshank discovered at the Royal College of Surgeons Library a manuscript that was Jenner’s original Communication to the Royal Society — differing substantially from the published Inquiry — which had lain in a drawer unnoticed since 1879. (Crookshank, Edgar M., 1889) The Royal Society rejected the communication; Crookshank argues the evidence was insufficient to justify publishing a recommendation for cowpox inoculation as a substitute for variolation. (Crookshank, Edgar M., 1889)

The Published Inquiry (1798)

Between the rejected manuscript and the published Inquiry, Jenner added new cases and re-inoculated Phipps with variolous matter, strengthening the evidence base before publication as a pamphlet. (Crookshank, Edgar M., 1889) Jenner’s three horsepox cases showed contradictory results: one subject resisted smallpox inoculation, another had eruptions, and a third contracted natural smallpox — undermining his horsepox-origin theory. (Crookshank, Edgar M., 1889)

The Inquiry itself refined the grease theory: Jenner argued in the published text that horse-grease virus passed through the cow became reliable vaccine, while horse-grease inoculated directly into humans did not reliably confer immunity against smallpox, a distinction he acknowledged required further experimental proof he had not yet obtained. (Crookshank, Edgar M., 1889) He attempted to close this gap before publication: to procure horse-grease virus he kept a horse on beans to make its heels swell and sent to Bristol for specimens, but all attempts failed before the pamphlet went to press. (Crookshank, Edgar M., 1889)

William Smith’s case — cowpox contracted in 1780, 1791, and 1794 with equal severity each time — directly contradicted the theory that a single attack of cowpox conferred lasting immunity, yet Jenner included the case without explanation. (Crookshank, Edgar M., 1889)

The Suppressed Fatality

John Baker, a five-year-old boy inoculated by Jenner on March 16, 1798, with horsepox matter, developed a pustule and subsequently died. Jenner suppressed this death in the published Inquiry, attributing it to a “contagious fever” caught in a workhouse. (Crookshank, Edgar M., 1889)

Immediate Consequences

London Reception

Henry Cline’s August 1798 vaccination trial in London succeeded: the child sickened on day 7, recovered by day 11, and subsequent challenge with variolous matter produced no disease — Cline called it “one of the greatest improvements that has ever been made in medicine.” (Crookshank, Edgar M., 1889)

After Jenner’s publication, Woodville at the Smallpox Hospital vaccinated extensively but in a variolous atmosphere, producing cases where cowpox and smallpox occurred simultaneously — generating generalized eruptions that Jenner blamed on contamination. (Crookshank, Edgar M., 1889)

Jenner introduced the concept of “spurious” versus “genuine” cowpox to explain vaccination failures, creating a classification that allowed him to explain away any contradictory result. (Crookshank, Edgar M., 1889) The published Inquiry formalized this device: any case where cowpox failed to confer immunity could be retrospectively reclassified as “spurious,” making the theory effectively non-falsifiable from within its own framework. (Crookshank, Edgar M., 1889) Crookshank argued that Jenner consciously avoided practicing in London because he feared rigorous challenge testing would expose failures in his theory. (Crookshank, Edgar M., 1889)

Priority Disputes

George Pearson independently investigated cowpox immunity in 1798, producing a competing volume within six months of Jenner’s Inquiry; Jenner responded by orchestrating press notices to protect his priority and eventually secured a Parliamentary grant of ten thousand pounds. (Crookshank, Edgar M., 1889)

State of Vaccine Knowledge

Practitioners at the National Vaccine Establishment and vaccination stations in the 1880s had no precise knowledge of the history and pathology of the diseases from which their lymph stocks had been obtained, being entirely occupied with vaccination technique. (Crookshank, Edgar M., 1889) To investigate the origins of the lymph in official use, Crookshank traveled to France in February 1888, consulting leading authorities in Paris, Bordeaux, Toulouse, and Montpellier, and obtained from Dr. Dubreuilh a full account of a “spontaneous” cowpox outbreak in Bordeaux that was the direct source of the official vaccine lymph then being used in Britain. (Crookshank, Edgar M., 1889) Crookshank’s investigation of vaccination originated from an 1887 cowpox outbreak in which he proved the cows had not been infected by milkers suffering from smallpox, contradicting commonly accepted doctrines. (Crookshank, Edgar M., 1889)

Long-term Significance

Eradication of Smallpox

Despite the contested evidentiary basis, vaccination proved effective enough in practice that it was gradually adopted worldwide. Compulsory vaccination laws were enacted in many countries during the nineteenth century, and the World Health Organization’s intensified eradication campaign, launched in 1967, achieved the global eradication of smallpox in 1980 — the only human disease ever eradicated by deliberate intervention.

The Heroic Narrative and Its Critics

The received account of Jenner as a lone discoverer who single-handedly conquered smallpox obscures several inconvenient facts: the dairymaid tradition predated him by generations; Jesty vaccinated deliberately 24 years before him; his evidentiary base consisted of one successful experiment with a short follow-up; he suppressed at least one fatality; and his horsepox-origin theory was contradicted by his own cases. Crookshank’s work, though controversial in its own time, anticipated modern historical scholarship on the complexity of scientific discovery.

Precedent for Public Health Intervention

Vaccination established the principle that the state could mandate a medical procedure for the prevention of epidemic disease. This principle became the foundation of modern public health law but also generated sustained anti-vaccination movements from the 1850s onward, raising questions about bodily autonomy, informed consent, and the limits of state medical authority that remain live issues.

Questions for review:

• Crookshank (1889) is a hostile primary source — brilliant scholarship but written to discredit vaccination. The page needs balancing from a pro-vaccination source or a neutral modern history (e.g., Bazin, Riedel, or Baxby).
• The Osler evidence on vaccination is thin in the cards. Osler’s Silliman Lectures mention Jenner but primarily in passing. More Osler cards may exist.
• The horsepox/grease theory (that cowpox originated from horsepox transmitted to cows) has been revisited by modern genomic studies. Worth a note?
• The Baker death suppression is a serious claim. Crookshank documents it thoroughly, but corroboration from another source would strengthen it.
• The connection to germ theory should be noted: vaccination worked before anyone understood WHY it worked.

See Also

• germ-theory
• edward-jenner
• variolation
• smallpox
• public-health
• anti-vaccination

Sources

• Crookshank, E.M. (1889). History and Pathology of Vaccination. 2 vols. H.K. Lewis. (source_id: crookshank-historyvaccination-1889)
• Osler, W. (1921). The Evolution of Modern Medicine. Yale University Press. (source_id: osler-evolution-modern-medicine-1921)

Editorial Notes

Gaps the encyclopaedia compiler flagged for future evidence work, collected from inline markers in the body and frontmatter.

osler21-ch03-006 removed from frontmatter evidence list (2026-05-01)

This ID (School of Salerno, from Osler’s Chapter III on Medieval Medicine) has no connection to the vaccination event. It was included in the frontmatter evidence list in error. The claim belongs on a medieval medicine or medical education page, not here. Osler’s Silliman Lectures do not address Jenner or vaccination in Chapter III. If Osler evidence on vaccination exists, it would be in a different chapter.

Eradication of Smallpox

Precedent for Public Health Intervention