While a substantial number of clinical studies evaluating intradermal (ID) delivery of vaccines have been performed, the majority of studies have not been designed to evaluate whether ID delivery is immunologically superior to other routes. In most cases, to simplify administration, a reduced dose (10 or 20%) delivered ID was compared to the full dose delivered either subcutaneously (SC) or intramuscularly (IM) . Only a few studies have compared delivery of the same dose of vaccine ID and SC/IM. Further research will be needed to establish whether the potential for dose-sparing is unique to ID delivery (PATH 2009 ). However, some ID delivery devices in development offer additional desirable features such as needle-free delivery or improved ease of administration, which may be drivers for further adoption of ID vaccine delivery even if there is no net immunologic benefit.