Immunity -The ability of the body to fight against the germs or any other harmful substances is called immunity. It is provided by the immune system of the body.
Immunisation - The process of making an individual's immune system fortified against an infectious agent through artificial means such as through vaccination is called immunisation .
Vaccinesare the suspension of killed or attenuated microbes, or a substance mimicking the disease-causing microbes that are administered into the body to improve the immune system against particular infection. They make the body produce antibodies. These antibodies remain in the blood for long duration. When the disease-causing germs enter the body for second time, these antibodies destroy them.
Vaccination may be defined as protection of the body from communicable diseases by the administration of vaccine.
Edward Jenner (1749 – 1823), an English doctor who invented the vaccine for small pox. He is also known as the ‘Father of immunology’. He was the first to develop vaccines, using living, virulent organisms for small pox.
In 1788, a small pox epidemic occurred in Gloucestershire in England. Edward Jenner observed that people who had previously suffered from cowpox (generally the milkmaids) were not affected by small pox during the epidemic.