[Hepatitis B immunization--when is a booster injection necessary?].

Over 10,000 high risk individuals in the Zurich area have been vaccinated against hepatitis B with 3 initial injections of 20 micrograms H-B-Vax. The question arises whether, and if so when, booster injections should be given. Concentrations and persistence of the protective anti-HBs antibodies of 158 successfully vaccinated individuals (medical staff, patients on hemodialysis or with renal transplants) were analyzed. The anti-HBs behaved typically in most individuals, reaching maximum levels in the 7th month (1 month after the third vaccine injection) and then falling gradually, more rapidly in the next following month than later. Persistence of antibodies depended on the maximum anti-HBs concentration reached initially. Three years after the first vaccine injection anti-HBs concentrations had fallen below 10 mIU/ml in all healthy individuals with initial concentrations between 10-99 mIU/ml, in 44% vaccinees with initial titers between 100 and 499 mIU/ml, in 17% individuals with initial anti-HBs between 500 and 1499 mIU/ml but in none of the vaccinees whose antibodies had originally been higher than 1500 microIU/ml. Anti-HBs were undetectable in 6% of all medical staff members, in 30% of hemodialysis patients and in 59% of patients with renal transplants. Several policies for booster injections are discussed. One possible approach is to measure anti-HBs in all vaccinees after completion of the initial immunization, a further booster injection being recommended individually on the basis of the calculated time when anti-HBs fall lower than, for example, 10 mIU/ml having regard to the initial anti-HBs concentration.(ABSTRACT TRUNCATED AT 250 WORDS)