Baby 7 years old second liver antibody did not have how to do

7-year-old child hepatitis B antibody disappeared, at this time can give the child hepatitis B vaccine supplement antibody injection. Hepatitis B vaccine divided into three injections, respectively in 0-1-6 months injection, the effective period of antibody after injection can reach 12 years, during this period if the antibody weakened or disappeared, you need to inject hepatitis B vaccine, prevent the body from being invaded by hepatitis B virus.