Vaccination is a way of acquiring or inducing resistance to infection.
In 1796 British physician Edward Jenner established the principle of vaccination when he immunized people against smallpox using a related and weakened cowpox virus. Since its development, immunization against influenza, polio, measles, rubella, whooping cough and other diseases has saved millions of lives worldwide and has enabled medical science to eradicate some diseases like smallpox on a global scale. This chart shows the precipitous drop in measles in the U.S. after the 1963 introduction of a vaccine for the disease. There are also increased case numbers that prove the case for immunization. In 1974 Great Britain dropped the whooping cough vaccination program.