A weak positive test for hepatitis B is only seen for hepatitis B surface antibodies, as various other tests do not show weak positive results. A weak positive test for hepatitis B surface antibody is used to determine if a booster shot of hepatitis B vaccine is needed after a hepatitis B vaccination. However, a weak positive test cannot determine the exact amount of hepatitis B surface antibody, and sometimes the qualitative test is not particularly accurate. If a quantitative test for hepatitis B surface antibody is done, it is likely to be less than 10 mIU/ml or more than 100 mIU/ml, which is outside the range of a weak positive test. Therefore, if you want to know the amount of hepatitis B surface antibody accurately, you need to do a quantitative test for hepatitis B surface antibody in order to determine more accurately whether you need three doses of hepatitis B vaccine again, or just one booster shot of hepatitis B vaccine, or even if you do not need hepatitis B vaccine at the moment.