Evaluation of the immunogenicity of hepatitis B vaccination in hematopoietic stem cell transplant recipients vaccinated with a hexavalent vaccine compared with patients vaccinated with a combined hepatitis A and B vaccine.

BACKGROUND

In 2020, the Catalan Department of Health recommended a pediatric hexavalent vaccine for adult hematopoietic stem cell transplant (HSCT) recipients. Previously, patients at our center received a combined hepatitis A + B vaccine with double the hepatitis B antigen content. The immunogenicity of the hexavalent formulation in this population remains unclear.

OBJECTIVE

To compare immunogenicity of two hepatitis B vaccination strategies in adult HSCT recipients and identify predictors of response.

METHODS

We conducted a retrospective cohort study including adult HSCT recipients vaccinated between 2017 and 2023 in a tertiary hospital in Barcelona. Patients received hepatitis A + B vaccine (2017-2019) or hexavalent vaccine (2020-2023). Seroprotection was defined as HBsAb ≥10 IU/mL one month after the third dose. Univariate and multivariate logistic regression were used to identify factors associated with seroresponse.

RESULTS

A total of 331 patients were included (median age 54.6 years; 42.3% female). Seroprotection rates were higher with the hexavalent vaccine compared to hepatitis A + B (70.1% vs. 42.3%; p < 0.001). Median HBsAb titers were higher but not statistically significant (668 vs. 375 IU/mL; p = 0.261) in the hexavalent group. In multivariate analysis, hexavalent vaccination (OR 4.27, 95% CI 2.88-6.36) and pre-HSCT seroprotection (OR 9.36, 95% CI 5.46-16.03) were associated with higher response. Tacrolimus use and multiple myeloma were associated with lower response.

CONCLUSIONS

Despite lower antigen content, the hexavalent vaccine was associated with significantly higher seroprotection in adult HSCT recipients. Pre-existing protective HBsAb titers enhanced response, whereas tacrolimus exposure and multiple myeloma were associated with reduced immunogenicity.