Vaccination

Vaccination is the process of producing immunity against a disease by exposing individuals to weakened, dead, or closely related (but relatively harmless) versions of the pathogen that causes this disease. With the advent of widespread vaccination within populations, rates of vaccine-preventable diseases have dropped dramatically, leading to significant decreases in both morbidity and mortality. Through vaccination, for example, smallpox has been completely eradicated and other diseases, such as polio and measles, are in the process of becoming eliminated. In spite of these successes, however, vaccination is not without controversy. Concerns over possible adverse effects have caused individuals in many areas of the world to question the benefit of vaccines.

Credit for the development of vaccination is given to Edward Jenner, an 18th century English physician. In ...