A major hurdle to swine influenza vaccination of young piglets is maternal antibody interference. This interference is transient as it disappears when pigs reach about 3 months of age. We vaccinated piglets without and with interfering maternal antibody using a recombinant vector vaccine. In the absence of interfering maternal antibody, the vaccine was effective in inducing a strong immune response and greatly reduced the amount of virus. However, this same recombinant vaccine was not effective when interfering maternal antibodies were present. We are currently trying a higher dose of vaccine and different genes from SIV in hopes we can overcome this maternal antibody. Preliminary data from these new studies are promising.