Give examples of how vaccines work

The discovery of vaccines is a landmark event in the history of human development. Because in a sense, the history of human reproduction is the history of human beings to fight with diseases and natural disasters, the most important means of controlling infectious diseases is prevention, and vaccination is considered to be the most effective measures. Facts have proved to be so, smallpox virus, which has threatened mankind for hundreds of years, was completely eliminated after the emergence of cowpox vaccine, ushering in the first victory of mankind's use of vaccines against viruses, and also more convinced of the role of vaccines in the control and elimination of infectious diseases. In the past 200 years, the vaccine family has been expanding and developing, and there are more than 20 kinds of vaccines currently used for human disease control, which are divided into traditional vaccines and new vaccines according to their technical characteristics. Traditional vaccines mainly include live attenuated and inactivated vaccines, while new vaccines are mainly genetic vaccines.

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