According to the U.S. Census Bureau, the average life expectancy at the beginning of the 20th century was 47.3 years. A century later, that number had increased to 77.85 years, due largely to the development of vaccinations and other treatments for deadly diseases. Of course, vaccines and treatments only work if they're given, which is why many of these diseases still persist in poorer, developing countries. Despite the success of vaccines, only one of these diseases -- smallpox -- has been erased from the globe.
Here are 12 diseases that could be completely eradicated from the world if vaccines were made available to all.