Smallpox was one of the most devastating diseases in human history, a highly contagious illness caused by a virus that killed roughly 30% of those who caught it and left survivors with permanent scars. The disease caused high fever and a distinctive rash of painful blisters that covered the entire body, including inside the mouth and throat.

For thousands of years, smallpox killed millions of people across every continent. Entire populations were devastated when the disease swept through communities. In the Americas, smallpox brought by European explorers in the 1500s killed an estimated 90% of some Indigenous populations who had never been exposed to it before.

The story of smallpox has a remarkable ending: in 1796, an English doctor named Edward Jenner discovered that people could be protected from smallpox by being infected with a related but milder disease called cowpox. This discovery led to the development of vaccination. Over the next 180 years, a worldwide vaccination campaign fought to eliminate smallpox completely. In 1980, the World Health Organization declared smallpox eradicated, meaning it no longer exists in nature anywhere on Earth. Smallpox remains the only major human disease ever completely eliminated through human effort, proving what medical science and global cooperation can accomplish.