Vaccines
A vaccine is a material containing weakened or killed pathogens and is used to produce immunity to a disease by stimulating the production of antibodies. In 1796, a British physician, Edward Jenner, Infected a young boy with cowpox, by injecting pus cells After the boy had recovered from cowpox, Jenner injected the pus cells from a smallpox patient into him. The boy did not get small pox. image source: Newswise So it became clear that inten tional infection with cowpox protected people from smallpox. This method was named "vaccination" and the substance used to vaccinate was called a "vaccine". The Mode of Action of Vaccines Pathogens contain special proteins called "antigens" When pathogens enter the body (blood) of host, these proteins stimulate the immune response in host i.e synthesis of "antibodies" Antibodies bind to pathogens and destroy them. In addition, "memory cells" are produced, which remain in blood and provide prote...