Smallpox declined gradually, until the WHO coordinated the global effort to eradicate it

In 1796, Edward Jenner developed the world’s first vaccine against smallpox. As it was refined and widely adopted, many countries in Europe and North America, the Soviet Union, and island nations eliminated smallpox through national vaccination programs.

But in the mid-20th century, the disease remained widespread across Africa and Asia, infecting tens of millions every year.

Before the World Health Organization (WHO) committed to eradication in 1959, few believed it was possible, given the failures of other eradication efforts like malaria. But smallpox had no animal reservoir, clear symptoms, and there was an effective, low-cost vaccine.

By 1967, the WHO intensified the eradication campaign with more funding. The strategy focused on “ring vaccination” — containing outbreaks by vaccinating people around each case — and embedding the work within local health programs.

As the chart shows, this approach worked swiftly: within a decade, the number of endemic countries fell to zero. Smallpox was officially declared eradicated in 1980, two centuries after Jenner’s discovery. It’s a lasting triumph of science and cooperation.