This observer-blind study , conducted in the United States ( US ) and Spain during the @-@ influenza season , evaluated the effect of Adjuvant System AS@ on specific T-cell responses to a seasonal trivalent influenza vaccine ( TIV ) in @ year-old adults.Medically-stable adults aged @ years were randomly allocated to receive a single dose of AS@-adjuvanted TIV ( TIV/AS@ ) or TIV .