Enhanced Memory Responses to Seasonal H1N1 Influenza Vaccination of the Skin with the Use of Vaccine-Coated Microneedles

Background. Morbidity and mortality due to influenza could be reduced by improved vaccination. Methods. To develop a novel skin delivery method that is simple and allows for easy self-administration, we prepared microneedle patches with stabilized influenza vaccine and investigated their protective immune responses. Results. Mice vaccinated with a single microneedle dose of trehalose-stabilized influenza vaccine developed strong antibody responses that were long-lived. Compared with traditional intramuscular vaccination, stabilized microneedle vaccination was superior in inducing protective immunity, as was evidenced by efficient clearance of virus from the lung and enhanced humoral and antibody-secreting cell immune responses after 100% survival from lethal challenge. Vaccine stabilization was found to be important, because mice vaccinated with an unstabilized microneedle vaccine elicited a weaker immunoglobulin G 2a antibody response, compared with the stabilized microneedle vaccine, and were only partially protected against viral challenge. Improved trafficking of dendritic cells to regional lymph nodes as a result of microneedle delivery to the skin might play a role in contributing to improved protective immunity. Conclusions. These findings suggest that vaccination of the skin using a microneedle patch can improve protective efficacy and induce long-term sustained immunogenicity and may also provide a simple method of administration to improve influenza vaccination coverage.