Influenza is primarily a virus infection of the respiratory tract mucosa from the nose to the terminal bronchioles. Immunity to influenza virus infection is mediated primarily by antibody in respiratory secretions at the mucosal surface. To meet the need for improved inactivated vaccines, one potential approach is to increase the frequency and magnitude of antibody in secretions by administering inactivated influenza virus vaccine (IVV) intranasally and to optimize responses by including a mucosal adjuvant. The primary hypothesis of this study is that Type 1 interferon (IFN) will provide an adjuvant effect at the respiratory mucosal surface for production of IgA and/or IgG antibody to the influenza strains when added to IVV and administered intranasally. The primary objective of the study is to determine whether including type 1 IFN with IVV, administered intranasally, to healthy adults will enhance antibody responses in nasal secretions compared to intranasal administration of IVV alone. This is a single-center, randomized, double-blind, clinical trial to determine if type 1 IFN will act as a mucosal adjuvant for antibody responses to influenza viruses after administration with IVV intranasally. Subjects will be healthy adults between the ages of 18 and 40. The study will enroll 30 subjects in each of three groups, a group given 0.6 ml of IVV, a group given 0.6 ml of IVV containing 1M units of IFN and a group given 0.7 ml of IVV containing 10M units of IFN. The vaccine or vaccine/interferon combination will be administered to the subjects intranasally once. Blood and nasal secretions will be obtained before vaccination and again two and four weeks after immunization. Each subject will be asked to complete a memory aid for seven days and to report any unexpected adverse events (AEs) to study personnel. The subject will report to the clinic or be contacted by phone or e-mail at six months after vaccination regarding occurrence of any unreported serious adverse events (SAEs). The three nasal secretions will be used for testing for IgA and IgG antibody to the A/H1N1 and A/H3N2 HA in enzyme-linked immunosorbent assay (ELISA) tests. The three blood samples will be tested in HAI and neutralization tests for antibody to the A/H1N1 and A/H3N2 vaccine antigens.