LONG-TERM EFFICACY AND IMMUNOLOGICAL MEMORY OF PLASMA-DERIVED HEPATITIS B VACCINE 11 YEARS AFTER INITIAL INOCULATION

The length of protection of hepatitis B vaccineand the effective time for vaccine booster doseshave not been defined.Most of studies suggestedthatthe vaccine was effective for8to1 0 years[1～ 5] .However,in most cases,the study design was notrigorous. Many were cross- sectional studies per-formed before and aftervaccination,orstudies thatcompared the vaccinees with the general popula-tion.A few of studies as by Hadler[1] et al .werebased on randomized,double- blind and placebo-controlled tria…

LONG-TERM EFFICACY AND IMMUNOLOGICAL MEMORY OF PLASMA-DERIVED HEPATITIS B VACCINE 11 YEARS AFTER INITIAL INOCULATION

Objective To assess the efficacy and the immunological memory of plasma-derived hepatitis B vac- cine 11 years after the initial inoculation. Methods A randomized, double-blind and placebo-controlled trial design was used. Results The immunogenicity and protection rate of the vaccine were good 1 1 years after vaccination, how- ever, from 9 to 11 years after vaccination, the perscn year HBV infection rate showed no noticeable difference be- tween the vaccine group and placebo-controls. Furthermore, the immunological memory remained 11 years after in- oculation, but was significantly lower than that observed in the past 10 years. Conclusion Vaccine protection wanes over the years. More information is needed to define the appropriate time for vaccine booster doses.