The traditional methods used for ID delivery of vaccines have limitations which may hinder adoption of ID delivery. Bifurcated needles and multipuncture devices have been used successfully for delivery of smallpox and BCG vaccines, but do not deliver reproducible quantities of vaccine antigen to the dermis and are therefore unlikely to be appropriate delivery devices for new vaccines (Lambert and Laurent 2008) . The Mantoux method of inserting a needle at a shallow angle into the skin can also be inconsistent, and requires additional training and skill to perform correctly (Flynn et al. 1994) . The perceived difficulty of performing an ID injection using this method may prevent development of vaccines for ID delivery. New generations of devices, such as those discussed in the rest of this article, may improve the reliability of ID delivery and enable adoption of the ID route for more vaccines.