Complete seroconversion by low-dose intradermal injection of recombinant hepatitis B vaccine in hemodialysis patients

The present study was undertaken to find out if the seroconversion rate of hemodialysis (HD) patients was enhanced by the intradermal (i.d.) inoculation of recombinant hepatitis B (HB) vaccine. Thirty-five HBs-Ag, HBs-Ab and HBc-Ag, HBc-Ab negative HD patients were divided into three groups: 14 patients in group I received 5 micrograms HBs Ag i.d. every 2 weeks, 13 patients in group II were given 2.5 micrograms HBs vaccine i.d. every 2 weeks, 5 times, then every week. The remaining 8 patients in group III were immunised with 10 micrograms HBs Ag every 4 weeks 5 times intramuscularly (i.m.), then 5 micrograms i.d., every 2 weeks until complete seroconversion. Antibody response to i.m. injection was poor and only 37.5% of patients developed anti-HBs at a titer of 10 mIU/ml or more at 16 weeks after the start of immunisation. However, this poor response was improved by i.d. injection. The time of seroconversion was significantly earlier and the rate of response was higher in group I. The poor response in group II was markedly improved by doubling the inoculation rate. Overall, 100% of seroconversion was finally obtained by multiple i.d. immunisation. However, the anti-HBs titers were lower in all patients and declined in some patients after the immunisation was stopped. The last seroconverted patient in each group lost protective antibody levels at the 39th week. These patients became antibody positive again at the 52nd week with a booster dose. We feel that the i.d. route remains a useful and cheaper method of obtaining prophylaxis against HBs in high-risk HD patients but it would seem to be prudent to monitor these patients serially to assess the persistence of anti-HBs in the serum.