Abstract
We conducted a 3-year follow-up study of 2, 008 individuals for the persistence of antibody levels after vaccination with a recombinant hepatitis B vaccine. At 1 month after vaccination had been completed 96.3 % of subjects had acquired protective HB surface (HBs) antibody titers on passive hemagglutination assay (PHA) of 23, and 3 years after completion of the vaccination 63.1 % had acquired similar titers. The titer decreased below this level after 3 years in 34.5 % of subjects who had initially acquired protective antibody titers. The mean acquired HBs antibody titer on PHA was 25.8 at 1 month and 23.1 at 3 years after completion of the vaccination. The regression line for these changes was expressed as logY = 1.800-0.24X by the least squares method. The antibody level was estimated to decrease to 23 at 37 months and to seronegativity at 75 months. On the basis of the relationship between PHA antibody titers and the period of their persistence, the persistence of antibody levels after vaccination with a recombinant vaccine can be estimated from the acquired antibody titer determined 1 month after completion of the vaccination, as with plasma-derived vaccines. (J. Oral Sci. 42, 147-150, 2000)
