How long does the effect of hepatitis B vaccine last?

The duration of hepatitis B vaccine is determined by the amount of hepatitis B antibodies. Generally, if the number of hepatitis B antibodies is high, the duration of maintenance is longer, and vice versa. When the number of hepatitis B antibodies decreases, it is necessary to inject hepatitis B vaccine again to produce protective effects. For patients with hepatitis B infection, further examinations need to be done to determine the status and severity of the infection, and a treatment plan needs to be formulated for treatment. After three injections of hepatitis B vaccine, antibodies will be produced on the surface of hepatitis B, and the specific duration of maintenance depends on the amount of hepatitis B antibodies. Hepatitis B vaccine is mainly targeted at the general population, and patients with negative results in hepatitis B two-half test. After injection, corresponding protective antibodies will be produced. Hepatitis B vaccine is ineffective for patients who are already infected with hepatitis B. The antibodies on the surface of hepatitis B will gradually decrease over time, at least for about 3-5 years. Further re-examination of hepatitis B two-half test is needed according to specific conditions. When the amount of hepatitis B surface antibodies returns to normal, further injection of hepatitis B vaccine is needed to produce protective antibodies again. If the amount of hepatitis B surface antibodies is higher, the corresponding duration of maintenance will be longer; if the amount is less, the corresponding duration of maintenance will be shorter. Patients with hepatitis B infection need further examination, including hepatitis B DNA, hepatobiliary color ultrasound, liver function, and alpha-fetoprotein, to further evaluate the severity of hepatitis B infection and determine further treatment plans.