Generally speaking, hepatitis B vaccination is not urgent for adults, but it is necessary for those who are so-called “high-risk”. What is “high risk”? It means people who have close contact with people who have chronic hepatitis B and have a greater chance of being infected by the hepatitis B virus. People with hepatitis B have a high level of virus in their bodies and may transmit it to people at risk through their blood or body fluids. Spouses (sexual partners) of patients with hepatitis B, medical workers, and also people who use drugs intravenously should be included in the high-risk group. For non-high-risk groups, vaccination is also advocated on a case-by-case basis, and some even advocate routine vaccination. In fact, this is only a concern, because there are many factors that influence whether or not one is infected with the hepatitis B virus. According to the general rule of pathogen infection, one must be susceptible to infection when more than one condition exists, such as a large amount of virus, a strong virulence of the virus and a low immunity of the person. For example, in the case of a blood transfusion, if the donor is infected with the hepatitis B virus, obviously his or her blood contains a large amount of virus and the recipient will receive a large amount of virus at one time, thus easily becoming infected with hepatitis B. If the recipient has been vaccinated and has the appropriate antibodies to the surface antigen of the hepatitis B virus, then even if a large amount of blood containing the virus is given, it will be neutralized by the antibodies already present in the body and thus will not be infected. This is the reason why the general population also needs to be vaccinated. Vaccination should be done at the CDC. Hospitals in general are not equipped with the vaccine, but some hepatitis clinics that specialize in infectious diseases are equipped with the vaccine, so those who need it can request it directly.