Which disease did Edward Jenner's vaccine target?

Edward Jenner’s vaccine targeted smallpox, one of history’s most devastating infectious diseases. In 1796, the English physician showed that exposure to material from cowpox lesions could protect a person against smallpox, a related disease caused by variola virus.

Jenner tested the idea after observing that milkmaids who had caught cowpox often seemed protected from smallpox. He inoculated eight-year-old James Phipps with material from a cowpox sore and later found that the boy did not develop smallpox after exposure to smallpox matter. Although Jenner’s methods would not meet modern research standards, the result helped launch vaccination as a medical practice.

The word “vaccine” comes from vaccinia, the scientific name associated with cowpox. Jenner did not create the first form of smallpox prevention—variolation had been practiced in parts of Asia, Africa, and the Ottoman Empire—but his cowpox approach was safer and became widely influential.

Smallpox was declared eradicated by the World Health Organization in 1980 after a global vaccination campaign. It remains the only human disease officially eradicated worldwide, making Jenner’s work a landmark in public health.