BCG is not a smallpox vaccine. BCG can be used to prevent tuberculosis infection, while smallpox vaccine prevents smallpox virus infection. BCG is a vaccine against tuberculosis. After vaccination, it can produce immunity against Mycobacterium tuberculosis, prevent the reproduction and spread of Mycobacterium tuberculosis in the body, and effectively prevent the occurrence of tuberculosis. And smallpox vaccine can prevent smallpox virus infection. At present, smallpox vaccine is no longer in use, and now smallpox is mainly prevented by cowpox vaccination. Because cowpox virus and smallpox virus have the same antigenicity, but the symptoms of cowpox are relatively milder, vaccination against cowpox can effectively prevent the occurrence of smallpox. If there is any discomfort after vaccination, it is recommended to go to the hospital for timely consultation to avoid delaying the condition.