Silent hepatitis-B immunization in laboratory technicians

Abstract

The present investigation was initiated to assess the demand for vaccination against hepatitis-B in a department of clinical chemistry. One hundred and twenty-eight employees enrolled for the test programme consisting primarily of screening for hepatitis-B antigen (HB_sAg) and antibody to hepatitis-B surface antigen (anti-HB_s). Surprisingly it was found, that 8 persons out of 58 who had also participated in a screening survey in 1978 had developed anti-HB_s. These persons, who had no history of hepatitis, were also positive for antibodies towards the core antigen of hepatitis-B (anti-HB_c). A seroconversion rate of 1.53/100/year for this material was calculated. Six persons who had contracted hepatitis-B during an epidemic 14 years previously, presented with very weak anti-HB_s reactivity, but were positive for anti-HB_c indicating, that anti-HB_c was the more stable indicator of past HBV infection. The cost-effectiveness of vaccination against HBV seems disputable compared with other protective measures. The high incidence of silent seroconversion indicates a chronic exposure to virus among the laboratory personnel. Therefore, safety precautions against virus exposure are highly recommended.

In consequence of the results of this study, we investigated laboratory areas for the presence of HB_sAg, using a moistened cotton swab for sampling the environmental surfaces of equipment and furniture [8]. In all, 143 samples were collected from 28 different sites, including laboratory equipment like centrifuges, samplers of automated equipment and numerous items used in the laboratory. In no instance was immunologic HB_sAg reactivity detected, whereas dried spots of patients' serum positive for HB_sAg rendered positive after sampling by the same technique.

Key Words:

• hepatitis
• hospital infections
• HB_sAg
• Anti-HB_s
• Anti-HB_c