A study of hepatitis B vaccine efficacy 10 years after compulsory vaccination in Egypt.

This study aimed to determine the protective efficacy of hepatitis B vaccine against infection and chronic carriage in 720 children aged 10 years who were vaccinated in infancy. All children were tested for hepatitis B serologic markers including hepatitis B surface antigen (HBsAg), antibody to hepatitis B surface antigen (anti-HBs), and antibody to hepatitis B core antigen (anti-HBc) using 3rd generation ELISA technique. Only 37.9% of vaccinated children had protective anti-HBs indicating its decay with time. Hepatitis B infection occurred in 6.8% of the vaccinated children and it induced a boosting effect on anti-HBs level. HBsAg was detected in 0.6% only of the vaccinated children. Thus we could conclude that up to 10 years, booster doses are unnecessary possibly due to protective anamnestic response to antigenic challenge. Further follow-up studies for longer duration than 10 years are needed especially during adolescence with the onset of sexual activity to monitor the vaccine efficacy in preventing chronic carriage and the possible necessity for booster doses.