Prevaccination screening of medical and dental students. Should low levels of antibody to hepatitis B surface antigen preclude vaccination?

The prevalence of hepatitis B virus (HBV) markers in 484 medical and 329 dental students was studied. Three students (0.9%) were hepatitis B surface antigen (HBsAg) reactive, and 46 students (5.7%) were reactive for antibody to HBsAg (anti-HBs). There was no difference in anti-HBs frequency between medical and dental students, and the prevalence of this marker was not associated with year in school. Of the 46 reactors, eight (17%) were nonreproducible and 38 (83%) were reproducibly reactive when the same samples were reanalyzed. Of note, all nonreproducible reactors exhibited anti-HBs sample-negative control (S/N) ratios of less than 10, and none were positive for antibody to hepatitis B core antigen (anti-HBc). Nineteen (50%) of the reproducible reactors had anti-HBs S/N ratios equal to or greater than 10, and only 15 (39%) were anti-HBc positive. In view of these observations, we do not recommend HBV screening in a vaccine program for health students. Due to the frequency with which low-level anti-HBs reactors without anti-HBc are found to be nonreproducibly positive, we are concerned by the potential overinterpretation of such results before the formulation of decisions about the need for vaccination.