Abstract
Background and Aims: The duration of protection provided by hepatitis B (HB) vaccine is still unknown but can be estimated indirectly by measuring the anamnestic immune response to booster doses of the vaccine.
Methods: We searched electronic databases and conference databases up to December 2008. We also screened reference lists of articles and contacted the authors and vaccine manufacturers for additional references. We included randomized and nonrandomized studies assessing the anamnestic immune response to the booster of HB vaccine in healthy participants 5 years or more after initial vaccination.
Results: The meta-analysis included 34 studies with 53 intervention groups and 4,479 individuals. The protective antibodies induced by initial vaccination waned over time; however, nonprotected vaccinees who had lost their antibodies to hepatitis B surface antigen (anti-HBs) over time responded strongly to the booster dose. The seroprotection rate of HB vaccine after the primary vaccination was 98.00% [95% confidence interval (CI): 95.32%, 99.52%] after 5 years, 96.88% [95% CI: 94.61%, 98.50%] after 6-10 years, 88.80% [95% CI: 79.84%, 95.08%] after 11-15 years, and 85.12% [95% CI: 82.18%, 88.20%] after 16-20 years.
Conclusions: According to these findings, the protection provided by HB vaccine is dependent on immune memory rather than anti-HBs titer; therefore, recommendations for booster doses should be based on immune memory instead of the persistence of antibody. In addition, a full course of HB vaccination can induce a long-term and strong serologic immunity against hepatitis B virus infection. Nonetheless, the decreasing trend of seroprotection during the first and second decades after immunization indicates that the long-term immunity induced by HB vaccine may diminish over time. This issue raises the possibility of the need for a booster dose, although universal revaccination does not seem necessary during the first and second decades after primary vaccination in healthy individuals with normal immune status who had fully responded to a complete course of the vaccine.
Keywords
Hepatitis B Vaccine Immunization Immunologic Memory Immunity
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