An earlier prototype of the BD microneedle using a 1 mm, 34 gauge needle has been tested in rats for delivery of influenza vaccines which showed dose sparing effects compared to an IM control. ID microneedle administration of a low dose (0.01 lg) of inactivated virus vaccine induced similar serum antibody response as IM injection of a dose 100 times larger (1 lg). Additionally, using microneedles for ID immunization with split-viron vaccine (seasonal H1N1 strain) showed approximately ten-fold dose-sparing compared to IM immunization. In the same study, ID immunization using plasmid DNA vaccine encoding the hemagglutinin protein of influenza A virus showed similar dose-sparing effects after multiple immunizations (Alarcon et al. 2007 ). The BD microneedle was also used to deliver a live attenuated vaccine against Japanese encephalitis (ChimeriVax TM -JE) in non-human primates. In this study, ID microneedle injection was compared to SC injection and transcutaneous microabrasion (see Sect. 6.1). The microneedle ID injection provided the best and most consistent immune responses (i.e., neutralizing antibodies) of the three types of immunizations .