Antibody Response to Vaccination
Licensed formulations for both vaccines produce high (
>95%) rates of protective antibody (anti-HBs >10 mIU/mL) when the complete series is administered in different schedules to infants, juveniles, and adults aged <40 years (
5). Among healthy adults, 30%--50% develop a protective antibody response after the first vaccine dose, 75% after the second dose, and >95% after the third dose (
5--9). Increasing the interval between the first and second dose of vaccine has little effect on immunogenicity or final antibody titer, although data are limited regarding intervals >2 months among adults (
5,8). The third dose confers the maximum rate of seroprotection; it primarily acts as a booster and confers optimal long-term protection through the induction of maximum immune memory (
5,9). Both licensed vaccines administered on a 0-, 1-, and 6-month schedule produce a >95% final seroprotection rate among adolescents and healthy young adults, and studies indicate that vaccination of adolescents and adults on a 0-, 2-, and 4-month, and adolescents on a 0-,12-, and 24-month schedule, achieved final seroprotection rates similar to the 0-, 1-, and 6-month schedule (
8--10). In addition, a 2-dose vaccination series using Recombivax HB? at the adult dosage has been demonstrated among adolescents aged 11--15 years to produce protective antibody responses equivalent to that of the 3-dose series, although the long-term protection afforded from this schedule is not known (
8,11).
The duration of vaccine-induced antibody and protection from hepatitis B virus (HBV) infection has been evaluated among vaccinated infants, juveniles, and adults (
5,12-
-14). Studies indicate that although loss of detectable anti-HBs has ranged from 13% to 60% by 9--15 years after vaccination, immune memory provides protection from HBV infection, and protection remains intact for
>15 years, the longest period for which follow-up data are available (
5,12-
-14). Because of the long duration of protection afforded by the 3-dose vaccine series, booster doses of vaccine are not needed among vaccinated immunocompetent juveniles or adults.