Smallpox plagued the human population for centuries, killing millions of people. Finally, in 1980, it was declared eradicated by the World Health Organization.

The eradication effort began in 1967 worldwide by the WHO. Smallpox affected 15 million people each year, with more than 2 million dying each year, and many more becoming permanently disfigured. The original plan was to perform mass vaccinations. The strategy was successful in less densely populated places, such as the U.S. and Western Europe. However, wide breakouts still occurred in densely populated places. The containment strategy was developed, necessitating fewer supplies. If someone was infected with smallpox, they tracked down every person that had contact with the victim and vaccinated them, stopping the spread of the virus throughout the population.
The original method of vaccination was to scratch the vaccine into the skin, which was ineffective for mass vaccination. The bifurcated needle was developed, and was in use everywhere in 1970. It has two prongs with a wire in between them to hold the vaccine. Another development which enabled wide vaccination was freeze-dried vaccine. The first vaccine could be easily contaminated and had to be used within 48 hours. The freeze-dried vaccine was much higher quality and was easily mass produced, enabling the vaccination campaign.
Training was extremely important in the campaign. Specific procedures were developed to deal with different situations, and involved field training and simulation exercises. House-to-house searches were performed, and watch guards were placed at infected homes and villages. The number of cases decreased each month until the final case occurred in 1977 in Somalia. The WHO declared the disease eradicated in 1980.
Smallpox played a major part in the history of the world. It caused civilizations to fall, and many gods were dedicated to the disease and its victims. It killed millions and millions of people, and it is estimated that if it had not been eradicated, another 40 million deaths would have occurred. This would have had a devastating effect on our world as we know it today, and many of the other inventions and discoveries probably would not have been made.