How did Edward Jenner develop the smallpox vaccine?

Edward Jenner developed the smallpox vaccine by using material from cowpox sores to create immunity against smallpox.

In the late 18th century, smallpox was a deadly disease causing severe illness and death. Edward Jenner, an English physician, noticed that milkmaids who had contracted cowpox, a much milder disease, seemed immune to smallpox. This observation led him to hypothesise that exposure to cowpox could protect against smallpox.

In 1796, Jenner conducted an experiment to test his theory. He took material from a cowpox sore on the hand of a milkmaid named Sarah Nelmes and inoculated it into the arm of an eight-year-old boy named James Phipps. James developed a mild case of cowpox but recovered quickly. Later, Jenner exposed James to smallpox, but the boy did not develop the disease, proving that the cowpox infection had made him immune to smallpox.

Jenner called this new method "vaccination," derived from "vacca," the Latin word for cow. He published his findings in 1798, and despite initial scepticism, his work gained acceptance. Vaccination gradually replaced the older, riskier method of variolation, which involved using material from smallpox sores and often led to severe illness or death.

Jenner's discovery was revolutionary, laying the foundation for modern immunology and leading to the eventual eradication of smallpox in 1980. His work demonstrated the potential of vaccines to control and eliminate infectious diseases, saving countless lives and transforming public health.