Immunisation against hepatitis B viral infection--a study of South African anaesthesiologists

The practice of anaesthesia involves exposure to blood or bloodstained secretions which may be contaminated with transmissible pathogens including the hepatitis B virus (HBV). This study was undertaken to assess the impact of freely available hepatitis B vaccine and applications of universal precautions against blood exposure on the uptake of immunisation and prevalence of HBV markers in South Africa anaesthesiologists.

Anaesthesiologists from the Department of Anaesthesia of the University of Natal and those attending a continuing medical education course in Cape Town in March 1993 participated in the study. Each participant completed a questionnaire giving details of previous exposure to HBV, immunisation status and details of immunisation. Blood samples were obtained on a voluntary basis for determination of HBV serology.

One hundred and twenty-one anaesthesiologists participated in the study; 36 were unimmunised, of whom 18 (50%) were seropositive for HBV markers. More experienced anaesthesiologists (> 10 years) tended both not to be immunised and to be seropositive, indicating previous exposure to HBV. Eighty-five participants were immunised. Intradermal immunisation caused significantly less seroconversion than the intramuscular route (35% v. 81%; P < 0.05). Of 7 non-responders to intradermal immunisation, 5 responded to a single intramuscular booster injection.

Exposure to HBV is common in anaesthetic practice, as evinced by the 50% seropositivity in unimmunised anaesthesiologists, which means that routine serological testing before immunisation is warranted. Intramuscular immunisation provides the best protection against HBV. Post-immunisation serological testing should be performed to demonstrate an adequate antibody response. The intradermal route may save cost with similar efficacy if combined with post-immunisation testing and a single intramuscular booster injection for non-responders.