Background: Primary prevention by vaccination remains the main goal in controlling HBV infections. Observational studies suggest that a primary series of vaccination started at birth provides protection for approximately 90% of recipients for at least 20 years. Data on response to a booster and long-term effects are lacking.
Methods: We evaluated the immunization status of 381 health care students who were immunized against HBV in the first year of life. Students were considered immune if antibody titers were ≥ 10 mIU/mL. We compared the results of students who were boosted at the age of 18 during paramedic training (boosted) to students who were not boosted since primary series (primary). Those who had low levels of antibodies were boosted and reassessed 6 months later.
Results: Of the 381 students, 305 only received the primary series and 76 were boosted on average 4 years earlier. The average age of both groups was 22. Only 126 (44%) of primary group had protective levels compared to 67 (88.2%) of boosted group p<0.001(figure 1). 8 students from the boosted group who had unprotective levels received an additional booster and all developed protective levels. Of the 135 from the primary series with unprotective levels 126 (93%) developed protective levels following booster.
Conclusion: An immunization series administered during the first year of life does not provide life time protection. A booster provided at the age of 18 augments the primary series and provides protective levels of antibodies for at least 4 years if not longer. Overall response to booster is high. This data suggests the need for a routine booster dose against HBV at the age of 18.
Figure 1 flow chart of health care students monitored for HBV immunization status
L. Nesher, None