Comparison of two immunization schedules with recombinant hepatitis B vaccine and natural immunity acquired by hepatitis B infection in dialysis patients.

In a prospective study over a 2-year period we compared two practical dosage schedules to vaccinate dialysis patients against hepatitis B virus (HBV) infection using a yeast-derived recombinant hepatitis B vaccine (Engerix-B). In addition, the natural history of this acquired immunity was compared with that developed through HBV infection in dialysis patients and healthy subjects. Patients on dialysis treatment (haemo or peritoneal) who were tested to be negative for hepatitis B surface antigen (HBsAg), anti-HBs and anti-HB core were allocated at random to receive HB vaccine according to one of the two schedules. The two groups receiving the vaccine were matched for age, sex, mean duration on dialysis and the form of dialysis treatment received. The group of patients who received a four-dose schedule (at 0, 1, 2 and 6 months) of 40 micrograms of HB vaccine each time (group 2) achieved a seroconversion rate of 79% 1 month after the last dose (at month 7) compared with a seroconversion rate of 55% in those who received three doses (at 0, 1 and 6 months) of 40 micrograms each (group 1). Healthy controls who received half the amount of vaccine on a three-dose schedule (group 3) attained 100% seroconversion (p < 0.05). When retested at 24 months, 30% of seroconverters in group 1 had lost their protective immunity, compared with only 6% in group 2 and 15% in group 3. The magnitude of antibody response (total and anti-(a)-specific) was assessed in the vaccinees at 24 months and compared with that of two other control groups, dialysis patients (group 4) and healthy volunteers (group 5), who had acquired immunity from HBV infection. In general, the total and anti-(a)-specific HBs titres in the dialysis patients (groups 1, 2 and 4) were lower than in their corresponding healthy controls (groups 3 and 5), irrespective of whether the protective immunity was acquired by vaccination or HBV infection. However, the anti-HBs titres in dialysis patients who received four doses were significantly higher than in those who received only three doses (p < 0.05), which indicated a better protective immunity in favour of the former regime. The magnitude of antibody response in the vaccinees of groups 2 and 3 compared well with their respective controls, groups 4 and 5, who had acquired their immunity through HBV infection. This implied that the yeast-derived vaccine was sufficiently immunogenic and provided lasting protection in patients and healthy subjects vaccinated by an appropriate dosage schedule.(ABSTRACT TRUNCATED AT 400 WORDS)