XXXX is the major determinant of humoral responses to the AS03-adjuvanted influenza A/09/H1N1 vaccine in allogeneic hematopoietic stem cell transplant recipients.

@entity1 @entity404 @entity2905 @entity2132 @entity405
BACKGROUND: Responses to influenza vaccines are poorly characterized in immunocompromised @entity1 . The goal of this study was to assess the efficacy of the AS03-adjuvanted influenza H1N1/A/09 vaccine in allogeneic hematopoietic stem cell transplant recipients. DESIGN AND METHODS: We enrolled 65 @entity1 and 138 controls in an open prospective study. Controls received one dose and @entity1 2 doses of the AS03-adjuvanted influenza H1N1/A/09 vaccine at a 3-week interval. Geometric mean titers and seroprotection/seroconversion rates were determined by hemagglutination inhibition before and four weeks after the last immunization. Clinical and biological markers, including immunoglobulins, CD3+, @entity404 +, @entity405 + and na  ve @entity404 + T-cell counts were assessed in all @entity1 . RESULTS: Baseline seroprotection rates were low in @entity1 (6.6%) and controls (14.8%). After 2 doses, @entity1 (n=57, 92.3%) achieved similar seroprotection rates (84% vs. 87%, P=0.65) and antibody titers (305 vs. 340, P=0.88) as controls (n=131, 93.9%) after one dose. In univariate analysis, transplant-to-vaccination interval less than 12 months, active @entity2132 , immunosuppressive drugs, hemoglobin less than 12 g/L, @entity2905 less than 1 G/L, IgG less than 4 g/L, IgA less than 0.5 g/L, IgM less than 0.5 g/L and naive @entity404 + T cells less than 150/ L were significantly associated with weaker responses. Multivariate analysis identified transplant-to-vaccination interval and active @entity2132 as the most powerful negative predictors of antibody responses (P=0.04 and P=0.002, respectively). Vaccination was well tolerated in both cohorts. CONCLUSIONS: In allogeneic hematopoietic stem cell transplant recipients, 2 doses of an adjuvanted influenza vaccine elicited comparable responses to a single dose in healthy individuals. However, vaccine responses remained poor in @entity1 with ongoing @entity2132 , supporting the need for additional strategies in this high-risk @entity1 population. (ClinicalTrials.gov Identifier: NCT01022905).
