Hepatitis B vaccine: simultaneous passive and active immunization. Indications in pre- and post-exposure

An alum bivalent hepatitis B vaccine (HB vaccine) containing 5 micrograms/dose of formalin-inactivated and purified HBsAg has been used for active immunization of dialysis patients since the fall of 1975. Elderly patients had a weak and delayed response to three injections of HB vaccine. They were thus at risk of being infected by HBV before the completion of immunization. To prevent these early infections a four-way passive-active immunization trial was undertaken. Patients received three or four injections of HB vaccine in combination with one or two injections of hyper-immune anti-HBs globulin (HBIG). Results show that passive anti-HBs did not impair the immune response to the vaccine. Moreover, immediate administration of HBIG upon entry in the dialysis centre significantly reduced early-acquired chronic HBs antigenaemia as compared to a group of patients receiving the HB vaccine alone. Passive-active immunization can also be used for post-exposure prophylaxis after accidental inoculation of HBsAg blood (needle-stick) or for the prevention of mother-infant transmission of HBV in children born to HBsAg/HBeAg positive mothers.