Transcutaneous immunization and immunostimulant strategies: capitalizing on the immunocompetence of the skin.

The skin is an attractive target for vaccine delivery. Topical application of adjuvants results in potent immune responses and good safety profiles. Adjuvants can be coadministered in a patch with vaccine antigens (transcutaneous immunization) or similar delivery format, or administered separately with an injection or IS™ patch (Iomai), leading to enhanced immune responses. These observations have moved into the clinic, highlighting the likelihood that skin delivery of vaccines will play an important future role in vaccine applications.