Herd Immunity Conferred By Hepatitis B Vaccination Increases the Protection Efficacy against Hepatitis B Virus Infection

Most of the chronic infections with Hepatitis B Virus (HBV) are acquired in perinatal period or in early life in China. We conducted HBV serosurveys in the same community among the age 5-6 year old children who were born in 1979-1980, in 1985-1986, and in 2002-2003, respectively. The seropositive rate of HBV surface antigen (HBsAg) was 11.43% in the unvaccinated population. It decreased to 2.08% among the vaccinated children born in the same year. With increased vaccination coverage the HBsAg seropositive rate decreased to 0.24% among the age 6-7 year old children born in 2002-2003, with 98.21% protection efficacy. Herd immunity conferred by HBV vaccination increases the protection efficacy against HBV infection.