In animal studies, we have demonstrated that the dose of an injected H5N1 vaccine candidate can be significantly reduced by using a skin patch containing E. coli heat-labile enterotoxin (LT) applied over the injection site. LT-activated epidermal Langerhans cells migrate to the nearby draining lymph node and enhance the immune response to the injected antigen. A dry patch formulation has been optimized as a dose sparing strategy for pandemic flu and other vaccines. Iomai Corporation has developed a proprietary stabilizing formulation for the patch that allows use and storage at ambient temperature. The patch withstands temperature extremes during shipment, and is suitable for stockpiling.