In 2002, China integrated hepatitis B vaccine (HepB) into its Expanded Program on Immunization (EPI) using HepB vaccine containing 5 µg of antigen. Although not recommended nationally, there was a common clinical practice in China of screening children for anti-HBs antibody level and giving a booster dose to HBV surface antigen (HBsAg)-negative children with non-protective anti-HBs antibody levels. We report an evaluation of the protective effectiveness of the 5 µg HepB vaccine and the serological response to the booster dose. We used data from a 2014 hepatitis B serological survey to determine HBsAg positivity and anti-HBs antibody levels among children who received and did not receive a booster dose. We determined HepB coverage from the Children Immunization Information Management System (CIIMS). We obtained and analyzed reports of acute Hepatitis B (AHB) during 2008-2014 obtained from the National Notifiable Disease Reporting System (NNDRS). The HBsAg-positive rate among children who had not received a booster dose was 0.41%, and did not increase with age (i.e., time since infant immunization). The anti-HBs positivity rate among the 6% of children who received a booster dose (88.41%) was higher than among those who had not received a booster (60.85%); anti-HBs antibody levels declined with age regardless of booster dose status. There was no statistically significant difference in HBsAg positivity between children who received a booster dose and those who did not. The AHB incidence among children born between 2002 and 2007 did not increase with age. Use of routine 5 µg HepB vaccine was not associated with an increase in AHB or of HBsAg positivity by time since vaccination, providing supportive evidence that individuals vaccinated with the 5 µg HepB vaccine do not need a booster dose. Although a booster dose was associated with increases in anti-HBs antibody levels, our study provided no evidence to support the need for this clinical practice. We should continue to strengthen serological monitoring of children, especially for those born to HBsAg positive mothers.