Of 1,801 Chinese subjects, age 1 to 90 years, screened for hepatitis B surface antigen and antibody (HBsAg, anti-HBs) and antibody to hepatitis B core antigen (anti-HBc), 214 (1 1.9%) had an isolated, positive anti-HBc result; anti-HBc was reproducibly present in the initial sera in only 66% and persisted after an interval of 2 weeks to 3 months in only 73%. There was a strong correlation between the rates of reproducibility and persistence of isolated anti-HBc and the initial anti-HBc titers. Thirty-two subjects with persistent, isolated anti-HBc received four doses of hepatitis B vaccine (5 pg, HEVAC B) at 0, 1, 2 and 12 months: 56% developed a primary anti-HBs response in response to hepatitis B vaccine, 16% developed an anamnestic or secondary anti-HBs response, and 28% were undetectable for anti-HBs even after four doses of vaccine. The low rates of reproducibility and persistence of anti-HBc together with the high rate of primary anti-HBs response to hepatitis B vaccine in subjects with isolated anti-HBc raise doubts as to the reliability of anti-HBc (Corzyme, Abbott Laboratories, North Chicago, Ill.) as a single screening test for hepatitis B infection prior to vaccination and suggests that subjects with isolated anti-HBc, in particular those with low anti-HBc titers, be included in vaccination programs.
The availability of safe and effective hepatitis B vaccines has prompted discussions concerning their most cost-effective use (1-3). In high-risk groups, screening with a single serologic test before vaccination is more cost-effective than universal vaccination (1, 4). An immunoassay for antibody to hepatitis B surface antigen (anti-HBs) is the most widely used test for screening. However, several prevaccination screening surveys have shown that 2 to 6% of subjects have low titers of anti-HBs without concomitant antibody to hepatitis B core antigen (anti-HBc) (5-11). In these subjects, the anti-HBs was usually of IgM class (6), poorly reproducible (8) or not persistent (8-10). Only 20 to 40% of those with isolated low titers of anti-HBs developed an anamnestic response to hepatitis B vaccine (9, 10; Perrillo, R. P. et