This is a phase I, double-blind, randomized, placebo-controlled trial with two groups of subjects to receive seasonal trivalent inactivated split virion influenza vaccine (A/H1N1; A/H3N2 and B strains) or placebo (phosphate buffered saline). A total of 60 healthy male and female adults 18 through 45 years of age will be randomized to receive vaccine (30) or placebo (30).