Whether hepatitis B virus infects the body and causes hepatitis depends not only on the hepatitis B virus, but also, and more importantly, on the response of the body’s immune system to the hepatitis B virus. If there is no external effect such as drugs, it usually goes through four stages. Stage 1: Immune tolerance phase. After the hepatitis B virus infects the body, it lives mainly in the liver cells. During this period, the body’s immune surveillance system does not recognize the hepatitis B virus and mistakes it for one of its own, so it does not remove it. These viruses are free to replicate in the liver cells and do not affect the normal function of the liver cells for the time being, nor does the liver show any inflammation. Hepatitis B carriers are in this immune tolerance state. Stage 2: Immune clearance period. After the hepatitis B virus has been latent in the body for a period of time (the latency period varies for each person), our immune surveillance system will slowly detect the “enemy” and initiate an immune response, producing corresponding immune cells and antibodies and other immune substances. These antibodies recognize the antigens of the hepatitis B virus and bind to them, forming immune complexes. These immune complexes are then engulfed by phagocytes in the body and excreted outside the cells. We can imagine the liver cells as a house, the hepatitis B virus is a group of thieves who sneak in, the body’s immune system is the monitor inside the house, and the immune substances are the police. When the monitoring system is alarmed, a group of policemen will come from all directions of the house. When the police and the thieves fight, the doors, windows and furniture inside the house will be easily broken. Therefore, liver cells in the immune clearance period have an inflammatory response because the virus and the immune system are “fighting” and making a mess of the liver cells. When the liver cells are “injured”, an inflammatory response occurs. At this time, the cell membrane permeability of the liver cells is changed or even damaged, and the transaminases inside the cells enter the bloodstream. A liver function test will reveal a significant increase in serum aminotransferases (i.e., elevated ALT levels), which is a signal that hepatitis may have developed and that the carrier may be developing hepatitis B. At this point, antiviral treatment should be considered. At this point, antiviral treatment should be considered. Stage 3: Inactive phase. After an intense battle, some of the hepatitis B virus will be cleared by the immune system, or the virus may be cleared by aggressive drug therapy. By viral clearance, we mean that the DNA of the hepatitis B virus is no longer detectable in the blood, but some of the virus may still remain in the liver. During this period, the hepatitis B virus is inactive, its replication ability is inhibited, and the virus level is low, so it will not be active for a while. Phase 4: Reactive phase. Patients in the inactive stage may become active again under certain triggers, such as a decline in immunity or chemotherapy, and the liver may show inflammatory reactions again, that is, the hepatitis may flare up again. In other words, people who are in the second and fourth stages of hepatitis B virus infection are the ones who need treatment for hepatitis, while those who are in the first and third stages do not need treatment for the time being, as long as they are reviewed regularly and their hepatitis B virus and liver are monitored on time.