May 14, 1796

Edward Jenner

Edward Jenner inoculates James Phipps with cowpox material

Two cuts, each about half an inch long, rubbed with matter from a sore on a dairymaid's hand. The protection test came 48 days later.

14 May 1796: Berkeley, Gloucestershire

On 14 May 1796, Edward Jenner deliberately inserted material from a cowpox sore into the arm of a healthy boy of about eight, James Phipps, to test whether induced cowpox could protect against smallpox. His published account says the matter came from a sore on the dairymaid Sarah Nelmes's hand, placed through two superficial incisions each about half an inch long.

This was not a smallpox inoculation, and not an injection: Jenner rubbed the material into shallow cuts in the skin.

A mild illness, then nothing

The procedure produced a local cowpox infection. Jenner recorded that Phipps felt underarm discomfort on day seven and was briefly chilly, headachy and without appetite on day nine — and was well the next morning.

Nothing about protection was demonstrated that day; the observable result was an induced cowpox infection.

The test that mattered, 48 days later

On 1 July 1796 Jenner challenged the boy with fresh smallpox material, and no smallpox disease followed. That challenge, and the cases that followed it, carried the claim — not the May inoculation.

Nor was Jenner the first to use cowpox deliberately: Benjamin Jesty had inoculated his wife and two sons 22 years earlier, and Peter Plett did so around 1791. Jenner's distinction lay in systematic experimentation, publication and promotion.

Sources

Researched 23 Aug 2026 6 sources 3 audit passes Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree about when this happened.

What the sources leave uncertain

The date is firmly supported by Jenner's 1798 account. The disputed element is the claim that this was the first smallpox vaccination: deliberate cowpox inoculations had been performed before Jenner, notably by Benjamin Jesty in 1774 and Peter Plett around 1791.
Jenner's 1798 publication calls the boy only a healthy child of about eight; his identity as James Phipps is established by associated historical records.
The organism in later smallpox vaccine stocks was vaccinia, whose precise historical relationship to cowpox and horsepox is complicated. The material used in this particular experiment was described as coming from Nelmes's naturally acquired cowpox lesion.