When it comes to Hepatitis B, we have to talk about the “two half pairs”. Hepatitis B surface antigen (HBsAg) is the shell antigen of the hepatitis B virus, which is not infectious per se, but its presence often indicates the presence of the hepatitis B virus, so it is a sign of having been infected with the hepatitis B virus. In acute hepatitis B patients, this indicator can mostly turn negative early in the course of the disease, and in chronic hepatitis B patients, this indicator can remain positive. Hepatitis B Surface Antibody (HBsAb): It is the protective antibody that the human body is immune to hepatitis B virus. It often appears positive in the late stage of hepatitis B recovery, when the surface antigen of hepatitis B has been negative for several months. After receiving hepatitis B vaccination, 90% of people can be positive for hepatitis B surface antibody. Hepatitis B e antigen: Hepatitis B e antigen positivity indicates that the hepatitis B virus is actively replicating in the body and is highly infectious. Hepatitis B e antigen can be detected at the same time or in the following days after hepatitis B virus infection. It gradually declines within 10 weeks after the onset of acute hepatitis B symptoms. In chronic hepatitis B, it can be divided into e antigen positive slow hepatitis B and e antigen negative slow hepatitis B. Hepatitis B e-antibody: Hepatitis B e-antibody positivity often occurs a few months after hepatitis B e-antigen has turned negative, and if the patient turns from a major tri-positive to a minor tri-positive during antiviral treatment, it often signals that the patient’s infectiousness has been significantly reduced, and that the degree of viral replication has been lowered or is in significant remission. However, there is another type of e antibody positive chronic hepatitis B. Not only can hepatitis B virus replication be exacerbated, but it is often accompanied by inflammatory activity and the presence of cirrhosis. Hepatitis B core antibody (anti-HBc): It is usually detected in the serum 3-5 weeks after the appearance of hepatitis B surface antigen and before the appearance of hepatitis symptoms. Large amounts of hepatitis B core antibodies often signal that the hepatitis B virus is replicating, is infectious, and can persist for years to decades. In general, a single positive hepatitis B core antibody indicates previous infection with the hepatitis B virus. If a single positive hepatitis B core antibody is followed by a positive serum HBVDNA, the patient may have occult hepatitis.