Alternative Methods of Vaccine Delivery: An Overview of Edible and Intradermal Vaccines

Criscuolo, E.; Caputo, V.; Diotti, R. A.; Sautto, G. A.; Kirchenbaum, G. A.; Clementi, N.

From a commercial point of view, intradermal vaccination has been primarily explored for its ability to elicit equivalent antibody responses at lower doses, a phenomenon typically described as "dose sparing" [113] . In this regard, the advantage of a low dose is most evident in high-surge situations, such as during pandemic and seasonal influenza waves, in which large populations are at an increased risk and large amounts of new antigen preparations are quickly required each year [114] [115] [116] . Above all, dose sparing is also important in a large-scale setting and in reducing the production-associated costs, especially in developing countries, where the price of the vaccine limits its use and coverage. In this regard, the U.S. Food and Drug Administration (FDA) approved the trivalent inactivated intradermal influenza vaccine for use in adults 18-64 years of age for use during the 2012-2013 season, and a quadrivalent formulation was subsequently approved in 2014. However, similar to intramuscular vaccines, the formulation of these approved intradermal vaccines is liquid and thus still dependent on the cold chain and administered through a syringe. For these reasons, novel dried solid microneedle devices, while eliciting comparable immunogenicity to intramuscular-administered vaccines, represent an innovative approach to facilitate self-administration and allow vaccine storage at room temperature [117] .