Concurrence of hepatitis B surface antibodies and surface antigen: implications for postvaccination control of health care workers

Among 1081 persons testing positive for hepatitis B surface antigen, 106 (10%) tested positive for antibodies to surface antigen (anti-HBs) in the same blood sample. Thirty of these persons were studied in detail: seven tested positive for hepatitis B e-antigen, nine were apparently healthy blood donors, and in 14 chronic infection could be demonstrated in follow-up samples. Frozen samples of 14 persons were available for additional quantitative anti-HBs testing using another anti-HBs assay: three showed no anti-HBs reactivity, seven showed borderline anti-HBs levels (1-5 IU/L), and anti-HBs titres ranged from 23 to 66 IU/L in four HBsAg-positive persons, including an apparently healthy blood donor. Thus, after hepatitis B vaccination of medical personnel, presence of anti-HBs may erroneously suggest immunity, while in fact chronic infection with hepatitis B virus is present