Vaccinations use the body's own immune system to prevent infection and reduce symptoms at the onset of disease. The French bacteriologist Pasteur gave the name "vaccine" to Jenner's idea of a smallpox vaccination method to prevent smallpox, and after researching the method, he found that it was effective in preventing the body from contracting infectious diseases by vaccinating the body in advance to create an immune system (a system that protects the body from bacteria). The "vaccination" was introduced to the world as a way to create immunity (a function to protect the body from bacteria) by inoculating the body with vaccines in advance in order to reduce the risk of contracting contagious diseases.