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

• 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 titers1:40 persisted for 50% of responding patients at 1yr. 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.

Nyckelord

pandemic H1N1

influenza A H1N1

hematological diseases

hematological malignancies

influenza vaccine

vaccine

immunocompromised

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