Which scientist developed the first widely used vaccine against smallpox?

Edward Jenner developed the first widely used vaccine against smallpox.

In 1796, the English physician tested the idea that infection with cowpox could protect a person from smallpox. He inoculated James Phipps, a boy, with material from cowpox lesions and later found that the boy resisted smallpox exposure. Jenner published his findings in 1798.

The word “vaccine” comes from vaccinia, the scientific name associated with cowpox. Jenner’s work built on earlier inoculation practices and did not create immunization from nothing, but it provided a safer and more systematic method than deliberate smallpox infection.

Smallpox became the first human disease eradicated worldwide. The World Health Organization declared it eradicated in 1980 after an international vaccination campaign. Jenner is often called the father of immunology, although modern vaccines use many different technologies.