One of the greatest triumphs of science, vaccinations have saved the lives of millions of people. Experts say widespread vaccination is a big part of why the average American lives more than 30 years longer today than he or she would have in 1900. All vaccines are important, but these have played special roles in the history of human health.

 

Smallpox

Pre-vaccine: Smallpox began its march against humans more than 12,000 years ago. In the 18th century, 400,000 Europeans died of smallpox every year and a third of the survivors went blind. Englishman Edward Jenner is credited with inventing the smallpox vaccine in 1796, but records show pioneers in China, India, Africa and the Middle East beat him to the idea. These older methods exposed healthy people to pus or scabs from live smallpox lesions. The inoculated often became sick, but usually less sick than if they’d contracted the virus naturally, and they gained immunity.

 

Jenner took a similar approach, but used cowpox—a safer relative of smallpox. The result was immunity for less risk.

 

Post-vaccine: Less than 200 years later, global vaccination campaigns succeeded in wiping out “wild” smallpox. Today, the virus exists only in laboratory vials. The vaccine hasn’t been given widely in the U.S. since 1972. It was the first vaccine to eradicate a disease.