Immunogenicity of hepatitis B vaccine among hemodialysis patients: effect of revaccination of non-responders and duration of protection.

BACKGROUND

Hepatitis B vaccination is recommended for patients on hemodialysis, however, seroprotection after a primary vaccine series is suboptimum. Limited data are available on the effect of revaccination of non-responders and on persistence of immunity in this population.

METHODS

Hepatitis B vaccine (40 μg/dose) was given to 77 susceptible patients on hemodialysis (0, 1, and 6 month schedule). Levels of hepatitis B surface antibody (anti-HBs) were tested ≥ 28 days after the third dose was administered, and non-responders revaccinated with an additional 3-dose series. Vaccine responders (anti-HBs ≥10 mIU/mL) were re-tested every 6 months and booster doses given as needed. Kaplan-Meier survival curve was used to estimate the probability of maintaining protective antibody level. Cox-proportional hazards models were used to assess the association between time to loss of protective antibody levels and certain explanatory variables.

RESULTS

Overall primary vaccine-induced response was 79.2% (95% CI 68.2%, 87.3%), including 49/77 (63.6%; 95% CI 51.8%, 74.7%) patients who received the initial primary hepatitis B vaccine series and 12/21 (57.1%; 95% CI 34.4%, 77.4%) non-responders who were revaccinated with an additional series. Among weak responders (anti-HBs level 10.0-99.9 mIU/mL), protective antibody levels persisted in 44% for 12 months post-vaccination; whereas among strong responders (anti-HBs level ≥100 mIU/mL), protective antibody levels persisted in 92% for 12 months, and 68% for 24 months post-vaccination. A weak post-vaccination response increased the risk of losing protective antibody levels (adjusted hazard ratio, 9.7; 95% confidence interval, 3.5-28.5; p<0.0001).

CONCLUSION

Revaccinating patients undergoing hemodialysis who do not respond to a primary vaccine series substantially increases the pool of protected patients. The threshold for defining hepatitis B vaccine-induced immunity should be revisited in this patient population to maximize the duration of protection.