Anti-HBs Levels 18-26 Years After the Initial Hepatitis B Vaccination Series in a Low-to-Medium Prevalence Region: Is a Booster Dose or a Second Vaccine Series Necessary?

Abstract

This cross-sectional study aimed to evaluate the persistence of immunity provided by hepatitis B (Hep B) vaccine 18-26 years after primary vaccination among 628 participants. Blood samples were collected for Hep B surface antigen (HBsAg), anti-HBs antibody (anti-HBs), and core antibody (anti-HBc) analyses. For participants with anti-HBs levels of < 10 mIU/mL, booster dose was administered and anti-HBs titers were monitored 4-6 weeks after vaccination was completed. If the response to Hep B vaccine was inadequate, two additional Hep B vaccine doses were administered. Of the 628 participants, 269 were excluded based on the exclusion criteria, and 359 were included in the final analysis. Three participants were found to be HBsAg-positive, resulting in an HBsAg carrier rate of 0.83%. Moreover, 55.4% participants had anti-HBs levels of ≥ 10 mIU/mL, with a geometric mean concentration (GMC) of 82.59 mIU/mL (95% confidence interval [CI]). Among 125 participants with anti-HBs levels of < 10 mIU/mL, 93.1% reached anti-HBs levels of ≥ 10 mIU/mL after booster dose, with a GMC of 493.47 mIU/mL. A prebooster anti-HBs cutoff level of 1.28 mIU/mL was predictive for an immune response, with a sensitivity and specificity of 71.2% and 71.4%, respectively (p = 0.001, 95% CI, likelihood ratio: 2.49). Among 14 participants unresponsive to the booster dose, 78.5% responded to the second vaccine series with a GMC of 670.82 mIU/mL. Approximately 44.6% of participants required a booster dose 18-26 years after primary vaccination. Prebooster anti-HBs titration may predict the response to booster doses. Further studies with larger groups are needed to confirm these findings.