ID vaccination has already made significant impact on public health as the primary means of immunization during smallpox eradication and continues to play a role in BCG and rabies vaccination in current clinical practice (Plotkin et al. 2008) . However, as discussed in this article, there are many more opportunities for ID vaccination to potentially improve immunogenicity and simplify logistics of the administration of other vaccines. A number of new ID vaccination technologies have been successful in human clinical trials. ID vaccination using the BD hollow microneedle was approved in Europe in 2009 for ID administration of the Sanofi Pasteur seasonal influenza vaccine and was introduced in Australia and New Zealand during the 2010 influenza season (Holland et al. 2008; Beran et al. 2009 ). This microneedle device may be adapted for use to administer other vaccines as well. Jet injectors have a long history of use for vaccination and are receiving renewed attention for ID delivery of vaccines in clinical trials, especially to address developing countries' needs, through support from WHO and US Centers for Disease Control and Prevention (see Sect. 3.1.2.). Skin abrasion as a pretreatment before applying a vaccine patch is also in clinical trials for prevention of influenza and traveler's diarrhea (Frech et al. 2005; Frech et al. 2008) . Projectile based delivery by EPI and PMED have been studied in a number of human clinical trials for both DNA and protein-based vaccines Jones et al. 2009 ), although it is unclear as to what extent this technology is under continued commercial development.