Vaccines are substances that are used to stimulate the body's immune response and provide immunity against a disease. Thanks to the discovery of immunity against smallpox by Dr. Edward Jenner in 1796 and the development of the first smallpox vaccine, Smallpox has been completely eradicated in the United States.
Since then, over the years, vaccines have prevented countless cases of diseases and saved millions of lives. Currently, there are over a dozen of vaccine preventable diseases (e.g., measles, mumps, tetanus, etc.), where vaccines are used routinely, safely and efficiently. In the future, futher understanding of how the immune system works will help scientists to harness the body's powerful immune system against other types of life threatening infectious diseases and even cancer.