Hepatitis B vaccination alone is not adequate for the categorizing of adult subjects with isolated anti-HBc.

To evaluate the meaning of isolated antibody to hepatitis B core antigen (anti-HBc), 88 Chinese subjects with isolated anti-HBc received rescreening of hepatitis B virus (HBV) markers. Eighty (90.9%) of them were still positive for this antibody and 29 were also found to be positive for antibody to hepatitis B surface antigen (anti-HBs). The remaining 51 subjects (58.0%) were positive for anti-HBc alone; 50 of them received a four-dose schedule of hepatitis B (HB) vaccine. After the initial dose, only one vaccinee disclosed an amnestic anti-HBs response, that is, anti-HBs titre > 1000 miu/mL. Forty-five vaccinees completed the vaccination schedule and 44 (97.8%) had anti-HBs response. The anti-HBs responses in 25 of these vaccinees were compared with 25 age- and sex-matched normal susceptible vaccinees. The anti-HBs response rates in both groups were the same (96 vs 96%). However, the geometric mean titre was significantly lower in the vaccinees with isolated anti-HBc (512 mIU/mL vs 4688 mIU/mL, P < 0.001). Prevaccinated sera were available in 49 vaccinees with isolated anti-HBc for detection of antibody to hepatitis B e antigen (anti-HBe) and HBV DNA; 37 (75.5%) of them had one or two of these markers. As we regarded the rescreening of HBV markers, response to hepatitis B vaccination and presence or absence of anti-HBe and/or HBV DNA together for categorizing the 88 subjects with isolated anti-HBc, at least three-quarters of them had past infection of HBV. The subjects with false positive anti-HBc test were a minor group.(ABSTRACT TRUNCATED AT 250 WORDS)