Figure 2From: Hepatitis B virus vaccination booster does not provide additional protection in adolescents: a cross-sectional school-based study The trend of anti-HBs seropositivity rate and median titers by different age group and time frame. (A) The trend of anti-HBs seropositive rate by age (2004-2012). (B) The trend of median titer value of anti-HBs by age (2007-2012).Back to article page