There is a long history of ID delivery via the jet injector route through the use of modified syringe orifice nozzles that can either have direct contact to the skin or can involve a setback feature or 'spacer' intended to introduce a gap between the nozzle orifice and the injection site, thereby weakening the injection stream and limiting deposition to the dermal space (Weniger and Papania 2008) (Figs. 2a, b) . MUNJI devices provided millions of ID smallpox doses during the implementation of the smallpox eradication program (Millar and Foege 1969; Weniger and Papania 2008) . Jet injectors have also been utilized historically for ID vaccination of rabies (Bernard et al. 1982; Bernard et al. 1987) , hepatitis A (Williams et al. 2000) , BCG (Paul et al. 1978; Parker 1984) , DTP combination vaccine (Stanfield et al. 1972) , measles (Burland 1969; Kok et al. 1983) , and influenza vaccine (Weniger and Papania 2008) .