PERSISTENCE OF ANTI-HBS ANTIBODIES IN HEALTH-CARE PERSONNEL VACCINATED WITH PLASMA-DERIVED HEPATITIS-B VACCINE AND RESPONSE TO RECOMBINANT-DNA HB BOOSTER VACCINE

Long-term persistence of specific antibodies after primary immunizatio n against HBV infection has been reported. In this study, we evaluated the persistence of anti-HBs in vaccinees 6 years after primary immuni zation and the response to a booster dose using a recombinant DNA yeas t-derived HB vaccine. An 85.4% seroprotection rate was observed after 6 years with a significantly higher seroprotective rate in those subje cts who received four closes of vaccine during primary immunization as compared with those who received three doses (93.9% versus 67.2%, p<0 .001). One month after receiving the booster dose, 98.6% of the subjec ts had an anamestic type of response. The GMTs were found to decrease progressively with increasing age. The antibody levels after booster d ose were higher than those attained at the end of primary immunization and reflected the the end seen before the administration of the boost er. These results are consistent with the existence of an effective im munological memory in HB vaccine responders. Subjects who received fou r noses during primary immunization were better seroprotected and had a higher seroprotection rate after the booster dose.