Adjuvanted influenza a (H1N1) 2009 vaccine in patients with hematological diseases: good safety and immunogenicity even in chemotherapy-treated patients

Abstract

Background: Patients with hematological malignancies are more susceptible to viral infections including influenza. In 2009, the World Health Organization classified the novel influenza A (H1N1) virus as pandemic. The potential impact of this pandemic for patients with hematological disorders was unknown. Institutional guidelines recommended two doses of AS03-adjuvanted influenza A (H1N1) 2009 pandemic vaccine for these patients.

Objectives: We aimed to determine the safety, immunogenicity, and clinical efficacy of this vaccine in patients with hematological diseases. Furthermore, we compared the immunological responses to that obtained by the non-adjuvanted trivalent seasonal influenza vaccine (TIV).

Methods: All included patients received adjuvanted pandemic vaccine and the majority received TIV. Serum for antibody analyses was collected at five time points.

Results: Thirty-one patients with different hematological diseases were included. After the second vaccine dose, a total of 25 (81%) reached both protective levels of antibodies and seroconversion response. Antibody titers ≥ 1 : 40 persisted for 50% of responding patients at 1 yr. Seroconversion was observed in 69% of 14 patients who had undergone hematopoietic stem cell transplantation and in all (9/9) patients with myeloma (five with ongoing treatment including high-dose corticosteroids). After vaccination with TIV, seroconversions against the three included strains were detected in 28%, 40%, and 20%. Response to the adjuvanted pandemic vaccine was superior (P < 0.009).

Conclusions: A substantial proportion of patients with hematological malignancies including patients undergoing chemotherapy mounted a good response to the adjuvanted pandemic vaccine. This vaccine had superior immunogenicity as compared to the non-adjuvanted TIV.