A randomized, controlled clinical trial to evaluate the immunogenicity of a PreS/S hepatitis B vaccine Sci-B-Vac™, as compared to Engerix B ® , among vaccine naïve and vaccine non-responder dialysis patients.

BACKGROUND: Dialysis patients have a suboptimal response to hepatitis B (HBV) vaccination. This study aimed to compare the immunogenicity of two vaccines: the third-generation Sci-B-Vac™ vs. the second-generation Engerix B® . The cohort included two groups of dialysis patients: naïve and previously vaccinated non-responders. Primary endpoints were antibody titers ≥10 IU/L at 3 and 7 month post-vaccination. Secondary objectives were seroprotection rates in vaccine-naïve patients and in previously vaccinated non-responders.

METHODS: Eighty-six patients were assigned to vaccine (Sci-B-Vac™ or Engerix B® ) using computer-generated randomization, stratified by age, gender, diabetes, and previous HBV vaccination. Sci-B-Vac™ was administered in three doses, 10 μg, at 0, 1, and 6 months in naïve patients; or 20 μg in previously vaccinated non-responders. Engerix B® included four doses, 40 μg at 0, 1, 2, and 6 months.

RESULTS: Each group had 43 patients. Seroconversion was 69.8% with Engerix B® vs. 73.2% with Sci-B-Vac™. Antibody titers at 7 months were higher with Sci-B-Vac™ (266.4 ± 383.9, median 53.4) than with Engerix® (193.2 ± 328.9, median 19). However, these differences were not significant, perhaps due to a suboptimal sample size.

CONCLUSIONS: This study suggests comparable immunogenicity for both vaccines. Thus, we cannot reject the null hypothesis that there is no difference in seroconversion by vaccine type. It is noteworthy that naïve patients were vaccinated with a standard dose of Sci-B-Vac™, while Engerix B® was administered at a double dose. Similarly, although mean antibody titer levels in the Sci-B-Vac™ group were higher than in the Engerix® group, this difference did not reach significance. Consequently, a future clinical trial should recruit a larger cohort of patients, using a standard double-dose protocol in both groups.