 Influenza virus is an important cause of morbidity in the transplant population and can lead to viral and bacterial pneumonia. Although the annual influenza vaccine is recommended for transplant patients, studies have shown that nonadjuvanted vaccine has poor immunogenicity. There are no studies that define the effect of adjuvanted vaccine in this population. The purpose of this study is to determine if a vaccination with FLUAD results in improved immunogenicity as compared to standard vaccine in allo-HSCT recipients. Immunogenicity will be assessed by standard quantitative antibody titer assessments and using cell-mediated immunity measurements. 