Vaccination

Vaccination is a preventative health measure that can confer immunity to an infectious disease, without requiring that the vaccinated individual actually contracts the disease. Usually, this is carried out with an innoculation, either a weakened form of the infectious agent (called a live vaccine) or a portion of the infectious agent, like an outer coat or internal proteins (called a killed vaccine) are introduced into the body of the individual to be protected. The immune system of that individual responds to the vaccine and, if that response is adequate, exposure to the germ will not result in sickness.

History of vaccination

"Edward Jenner vaccinated James Phipps in 1796 with cowpox obtained from a pustule on the hand of the milkmaid, Sarah Nelmes." ( Morgan, A. J.; Parker, S. Translational Mini-Review Series on Vaccines: The Edward Jenner Museum and the history of vaccination Clinical & Experimental Immunology, Volume 147, Number 3, March 2007, pp. 389-394(6)). He did so having thought out a rational plan for why this act might confer protection, and went on to further investigate vaccination as a means to prevent disease and so has become credited as the inventor of vaccination. However, other individuals used cowpox to innoculate family members even before Jenner, and an understanding of the immunity conferred by infectious diseases to subsequent exposure can be traced back for at least 500 years before Jenner's birth.