Ancient art, modern medicine

Some of the first vaccine-like treatments were developed over three hundred years ago in China and India. Powdered scabs from people infected with smallpox were given to healthy patients to help them build resistance to the deadly smallpox virus. The process developed immunity in some patients, but it could be unpredictable and unsafe. As doctors and scientists learned more about the way diseases work, they created safer, more effective vaccines. Ingredients are now added to vaccines to ensure that the material they contain is safe and will remain potent for a long time.

Many painful and often permanently debilitating diseases have been nearly wiped out by vaccinations. Once common, the viruses that cause polio, mumps, measles and rubella now only surface in areas with little access to vaccines or a large number of people who object to receiving them. In the same way a vaccine helps keep an individual from getting sick, when more people in a group are vaccinated against a disease it’s much harder for an outbreak to occur. When enough people are vaccinated, a disease can essentially disappear from the planet—the smallpox vaccination campaign was so effective that the deadly virus, which had plagued humanity for thousands of years, has been all but eradicated.