Hepatitis B vaccination 3 times according to the prescribed time, a few months later to review the five indicators of the hepatitis B virus, does not produce antibodies is often consulted by many friends, there are probably the following situations: 1, the detection method is not accurate: the actual has produced antibodies, but the results are negative because the detection method is not accurate. In this case, the most sensitive method, such as enzyme-linked immunoassay or radioimmunoassay, should be used to re-test. False negative results are obtained because some detection methods are not advanced or sensitive. 2. Weak immune response: The body’s immune response to the vaccine is too weak, producing only a small amount of antibodies, so that the advanced detection methods still fail to detect traces of surface antibodies. At this time, the dose of hepatitis B vaccine can be increased (10 micrograms each time) and injected once a month for a total of 3 times. At the same time, the combination of hepatitis B vaccine with other immune-stimulating drugs, such as porcine polysaccharide and BCG vaccine, is thought to improve the immune effect. 3. Occult infection has occurred: If surface antibodies are not produced even after vaccination according to the prescribed time, PCR (in vitro nucleic acid amplification technology) method can be applied to detect hepatitis B virus nucleic acid (HBV-DNA) in the serum of the vaccinated person. This is because there are a few patients who are actually infected with hepatitis B virus, but whose hepatitis B surface antigen (HBsAg) is so small that it cannot be detected by existing detection methods, or whose hepatitis B virus has mutated and does not react with common reagents, and there may be other reasons as well. Although these patients have been infected with hepatitis B virus, they do not produce an immune response and the organism is in a state of immune tolerance, and in this case, surface antibodies will not be produced when the hepatitis B vaccine is administered again. Alternatively, other hepatitis B virus markers such as core antibody (anti-HBc), e antibody, and e antigen can be tested for positivity. If it is positive, it means that the virus is infected, in this case, the hepatitis B vaccine may not produce anti-HBs even if it is given again. 4. Family history of hepatitis B: or people who have frequent contact with hepatitis B patients should pay special attention to the effect of hepatitis B vaccination. The chance of hepatitis B family members being infected with hepatitis B virus is extremely high, and there are some members who are infected with hepatitis B virus and appear to be insidious. Children born to people with hepatitis B should always be given the hepatitis B vaccine in a timely manner after birth, as this will block most of the transmission of the hepatitis B virus. However, even with timely hepatitis B vaccination, there are still very few newborns who fail immunization, which may be related to maternal intrauterine infection with hepatitis B virus during pregnancy and genetic factors. Parents need not make a fuss about this and should not use drugs indiscriminately; it is vital to review regularly and pay attention to changes in liver function. 5, immunocompromised, immunodeficient people: people with similar conditions do not easily produce antibodies, such as end-stage renal disease, after organ transplantation, AIDS-infected people, etc. 6.Mutation of hepatitis B virus: mutated virus with new biological characteristics can make the hepatitis B vaccine unable to work. In addition, some people infected with hepatitis B virus have different subtypes of hepatitis B virus surface antigen. There are various subtypes, and the hepatitis B vaccine is designed for the main virus subtypes, so there are inevitably subtypes that cannot be taken into account, and if it is a rare virus subtype, the hepatitis B vaccine will not have a protective effect. In addition, even if some people receive the whole hepatitis B vaccine, 5% to 10% of the vaccinated people do not produce hepatitis B antibodies or only produce low titers of antibodies, so children who do not respond or have low responses should receive hepatitis B vaccine several times until antibodies are produced.