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.

Intradermal vaccination has been demonstrated to be very safe. In fact, novel devices involve the use of needles with a smaller size than the usual (25 μm and 1 mm) and make it possible to bypass the corneous layer of epidermis by creating transient micropores in the cutaneous tissues. Even if some studies have shown that intradermal vaccination can be associated with a higher incidence of local reactogenicity, including primarily mild pain, swelling, and redness, systemic side effects have not been reported. In fact, the intradermal route limits the transfer of vaccine components to the blood circulation (and the risk of septic shock) and the possible toxicity due to hepatic first-pass effect [107] . Typically, when present, local effects resolve quickly, as reported in a study comparing the safety and immunogenicity of a large number of intradermal versus intramuscular influenza vaccines [108] .