Jenner's early education included a spell at Cirencester Grammar School, where one of the school 'houses' was named after him in later years to commemorate his achievements.
In Jenner's time, the practice of smallpox inoculation was commonplace in England. However it had two major disadvantages: it was dangerous, and until the infection from inoculation had run its course, the subject was infected, and infectious, with actual smallpox. This made them a risk to any family or acquaintances not already immune.
There was a local folk tradition amongst those who milked cows, that an infection with the so-called 'cowpox' protected one from contracting smallpox. (It has been theorized that the romantic image of the beautiful milkmaid came from the fact that milkmaids often contracted cowpox, and would thereafter be immune to the disfigurement of smallpox.)
Cowpox is related to smallpox and Jenner realised that if the folk tradition were true it offered considerable advantages over the use of smallpox in inoculation. On May 14, 1796, he tested cowpox, infecting an eight year old boy named James Phipps in the same manner as used in smallpox inoculation, but using material from a cowpox pustule. The boy contracted cowpox, and after six weeks, recovered safely. Jenner then applied the standard smallpox inoculation; the boy was completely unaffected, showing that cowpox had made him immune to smallpox.
Jenner called his method vaccination, as the original infective material came from a cow (Vacca is Latin for a cow). His work was published as "An Inquiry into the Causes and Effects of the Variolae Vaccinae, a Disease Known by the Name of Cow Pox" in 1798. The term virus was introduced in the work aforementioned.
Jenner realised the long-term implications of vaccination, and looked forward to the day when smallpox would no longer be a threat anywhere on earth; his dream eventually reached fruition with the global eradication of smallpox in the late 1970s.
For this pioneering work in vaccination Jenner is regarded as the Father of Immunization.
He studied anatomy and surgery under the guidance of John Hunter, a prominent surgeon in London, then returned to Berkeley to start a practice.
Jenner's house in Berkeley, also known as The Chantry, is now the Jenner Museum.
One of Jenner's interests was hot air ballooning. Together with the owner of Berkeley Castle, he made a successful flight to nearby Stroud. The spot where the balloon descended is today the location of the "Air Balloon" public house.
Jenner was a keen observer of nature and he was one of the first to write about the baby cuckoo's action of pushing the eggs and the young of its host out of the nest so that the baby cuckoo was the only one to receive food from its foster parents. It was for this observation that he was elected a Fellow of the Royal Society in 1789.