Vaccine delivery: Overcoming the challenges of vaccinating livestock and wildlife

The hypodermic syringe and needle are the leading technology in vaccine administration as they provide immediate and direct dosing at a low cost. This is convenient for administration of initial and booster doses for humans, however, for livestock and wildlife, multiple doses can be problematic due to accessibility and housing issues. Devices for delayed/multi-dose delivery of vaccines are becoming increasingly popular as they have the potential to stimulate full immunity from a single injection and can be altered depending on the pathogen and target species. The current challenge with delayed/multi-dose delivery devices is that they are not progressing to commercial development for numerous reasons. This review aims to investigate currently research devices and examine how these devices can be implemented in livestock and wildlife populations.