Variolation shortly after variolation began to outweigh the benefits of the procedure. From the 1760s, a number of individuals, including John Fewster, Peter Plett, Benjamin Jesty, and particularly Edward Jenner, were interested in the use of material from cowpox, an animal infection, to protect against smallpox. In 1796, Jenner vaccinated James Phipps, did more vaccinations in 1798, and was the first to publish evidence that cowpox protected against smallpox, was safer than variolation, and that his vaccine could be maintained by arm-to-arm transfer. The use of variolation soon began to decline as the smallpox vaccine became widely used and its benefits
History of smallpox cowpox were arising. Jenner was missing crucial information which he later discovered in 1796. Jenner hypothesized that in order to become immune to smallpox using cowpox, the matter from the cowpox pustules must be administered at maximum potency; else it was too weak to be effective in creating immunity to smallpox. He deduced that cowpox was most likely to transfer immunity from smallpox if administered at the eighth day of the disease. On May 14, 1796, he performed an experiment in which he took pus from a sore of a cowpox infected milkmaid named Sarah Nelmes and applied it to