Jenner Smallpox Vaccination

Setting the scene

Edward Jenner performed the first smallpox vaccination on May 14, 1796, in Berkeley, Gloucestershire, England. Smallpox killed 400,000 Europeans annually and was a leading cause of death, with 30% mortality. Variolation—deliberate infection with smallpox matter to induce mild disease—was practiced but risky, with 1-2% mortality. Jenner, a country physician, had noticed that milkmaids who contracted cowpox, a mild disease from cattle, seemed immune to smallpox. He hypothesized that cowpox infection protected against smallpox.

What happened

On May 14, 1796, Jenner took pus from a cowpox sore on milkmaid Sarah Nelmes's hand and inoculated 8-year-old James Phipps, his gardener's son. Phipps developed mild cowpox, recovered, and on July 1, Jenner inoculated him with smallpox matter—Phipps showed no disease, proving immunity. Jenner repeated the experiment on others, including his own son, and published his findings in 1798 as An Inquiry into the Causes and Effects of the Variolae Vaccinae. He coined 'vaccination' from vacca, Latin for cow.

Why it still matters

Jenner's discovery was revolutionary—vaccination was safer than variolation and provided lasting immunity. Despite initial skepticism and opposition (including claims it would turn people into cows), vaccination spread rapidly. By 1800, 100,000 people had been vaccinated in Europe. Napoleon vaccinated his army, and Thomas Jefferson championed it in America. Jenner's work laid the foundation for immunology and led to smallpox eradication in 1980—the only human disease eradicated. His method of testing a hypothesis through experiment established the principle of vaccination that has saved hundreds of millions of lives.

Background

Vaccination eventually curbed smallpox worldwide.