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Microneedle influenza vaccine delivery effective in mice
A novel, pain-free method of vaccine delivery has the potential to improve seasonal influenza vaccine coverage.
Researchers from Emory University and the Georgia Institute of Technology have found that influenza vaccine delivery via microneedle skin patches induced an immune response in mice that protected them from challenge with the virus, raising the possibility of an alternative route of immunization. Results from studies using two different vaccine strains (inactivated influenza virus A/PR/8/34 [IIV] and inactivated A/Aichi/2/68 [H3N2]) have been published in Proceedings of the National Academy of Science and PLoS ONE .
The team coated solid metal microneedles with inactivated virus and applied an array of these needles onto the skin of mice. The immune response induced in these mice was compared with a second group that received the same dose of vaccine via hypodermic intramuscular injection. The two groups demonstrated comparable antibody responses and levels of hemagglutination inhibition activity. In addition, both groups were later exposed to a lethal dose of a mouse-adapted influenza virus and survived.
Cutaneous immunization is known to be effective, particularly in those aged over 60 years; however, to date, the technique has not been widely used owing to its inconvenience and the level of training required by personnel for administration. The microneedle patch provides a method whereby cutaneous vaccination is made simple. Mark Prausnitz (Georgia Tech School of Chemical and Biomolecular Engineering) points out: "Unlike conventional hypodermic injections, microneedles are prepared in a patch for simple administration, possibly by patients themselves, and inserted painlessly onto the skin without specialized training."
Seasonal influenza affects thousands of people worldwide each year, and annual vaccination is recommended for high-risk populations. A simple, less painful method of vaccination would, the authors believe, increase vaccine coverage presently achieved with conventional vaccine injection. However, the team hopes that the effects of their research will extend further, as the delivery method could be applied to vaccines beyond influenza. The technique has many advantages over conventional methods, such as more convenient delivery and storage, increased vaccine safety (reduced re-use of hypodermic needles) and lower dosage requirements. As Prausnitz commented, "The possibility of replacing a hypodermic needle with a microneedle patch should significantly impact the way that other vaccines are delivered."
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