NIAID CEIRS | Research Publication Commentary
Young children are one of the most susceptible populations to influenza and on average represent approximately 20,000 hospitalizations and over 100 deaths due to influenza in the US annually. While current intramuscular influenza vaccines are highly effective in adults, these benefits are reduced in children because they have weaker immune responses. The skin has recently gained attention as a vaccine delivery route because the subcutaneous layers of the skin contain large networks of antigen-presenting cells that facilitate the adaptive immune response. Several studies have shown that delivering an influenza vaccine through the skin with microneedle patches leads to an enhanced immune response in adult mice, and an intradermal flu vaccine is currently available for use in adults 18-64 years old. In this study, Dr. Dimitrios Koutsonanos and the research team investigate whether influenza vaccines delivered via microneedles in the skin could increase protection against influenza in young mice.
Koutsonanos et al. compared immune responses in two-week old mice after immunization with either microneedle patches or intramuscular injections. Mice that received the vaccine through microneedle patches not only had significantly higher antibody levels than intramuscularly immunized mice, but also had levels similar to those measured in intramuscular- or microneedle-immunized adult mice. The young mice that received the microneedle-based immunization also exhibited significantly greater numbers of antibody-secreting cells in the bone marrow than intramuscularly immunized mice. These results suggest that vaccine delivery through the skin produces higher levels of functional antibodies than intramuscular immunization in young mice. One month after immunization, mice were exposed to a lethal dose of H1N1 influenza virus and monitored for morbidity and mortality. Both groups exhibited disease symptoms; however, all of the mice immunized with microneedle patches survived, while intramuscularly vaccinated mice had a mortality rate of 40%.
This study demonstrates that microneedle immunization against H1N1 offers a higher antibody response and greater immune protection for young mice than intramuscular immunization. Though more research is needed, these results suggest that microneedles could be a more effective delivery route for influenza vaccines in young children than traditional intramuscular injections.