ABSTRACT
Immunization using vaccines has played a vital role in eradicating and limiting the spread of several dangerous infections over the years. However, the threat of bioterrorism that rose in 2001 from the anthrax spores sent via the postal service and the pandemic caused in 2009 due to the H1N1 virus necessitated the need to investigate faster and more ef•cient vaccine delivery systems. This has brought a renewed interest to develop methods suited for mass immunizations. Currently, vaccines are typically administered by parenteral, intranasal, or oral routes. The majority of vaccines are administered by intramuscular or subcutaneous route using needle sticks with hypodermic needles. However, this mode of administration has several inherent disadvantages. These include possible pain and tissue reactions at site of administration resulting in poor patient compliance. Furthermore, the involvement of trained medical personnel adds to the cost of the health-care system. To add to the complications, a cold chain is often required for storage of the vaccines, and reuse of nonsterile syringes is a major source of hepatitis B infections. Noninvasive routes of administration have therefore been explored and, in many cases, provide the further advantage of inducing mucosal immune responses in addition to systemic immune responses (1,2). Some of the needle-free approaches that have been explored include jet injectors, mucosal immunization, and transcutaneous immunization (3,4).
