Smallpox virus was eradicated because of the emergence of the vaccine. Smallpox virus is a highly contagious, rapid-onset, severe and deadly virus that can be spread by droplets and patients may develop severe flu symptoms such as high fever, extreme malaise, chills and headache after infection. For a long time in the past, smallpox was one of the infectious diseases that seriously affected people’s lives, and with the development of medical technology, the human pox inoculation method invented in China and the cowpox inoculation method invented by British doctors played an important role in the eradication of smallpox. Initially using the human pox inoculation method, pox powder or pox fluid was taken from people who had smallpox and inoculated to people who did not have smallpox, while later the British doctor discovered that cowpox was a mild disease suffered by cattle and could be transmitted to humans, and most dairy women or farmers who had contracted cowpox were not infected with smallpox, he then began careful research and succeeded in developing a cowpox vaccine. Because the smallpox virus has a fatal disadvantage that it can only survive in the human body, that is, humans are the only host of the smallpox virus, and when humans are widely vaccinated, smallpox can no longer survive. Therefore, after widespread vaccination with cowpox, the incidence of smallpox decreased significantly until 1980, when the World Health Organization officially announced that the smallpox virus had been successfully eradicated, so that babies now generally do not need to be vaccinated against smallpox.