Smallpox virus is a virus belonging to Hazard Category I and Biosafety Level 4. And smallpox is a category B infectious disease caused by the smallpox virus. Smallpox virus reproduces very quickly and can be spread through the air and spreads quickly. An infected person is most contagious for 1 week after infection. It remains contagious until the skin on the affected area is scarred and falls off. There are also different types of smallpox virus, and different types of smallpox virus cause different levels of infection in humans. Most smallpox infections can be cured. The incubation period of smallpox virus infection is about 12 days. The initial stage of infection is accompanied by symptoms such as high fever, fatigue and headache. After about 2 to 3 days, it is accompanied by a typical smallpox rash, mostly on the face, arms and legs. Since the availability of vaccine, human beings have effectively prevented the smallpox virus by vaccinating against cowpox, and now smallpox has been eradicated and is no longer vaccinated and is no longer included in our infectious disease law.