A team of researchers from Georgia Tech has demonstrated that using microneedle patches to deliver influenza vaccination is just as effective as intramuscular hypodermic injections, at least in mice. The method is essentially pain free and doesn’t involve scary needles, which should make compliance much easier to achieve with fewer tears shed.
The patches used in the experiments contained an array of stainless steel microneedles coated with inactivated influenza virus. The patches were pressed manually into the skin and after a few minutes, the vaccine coating dissolved off within the skin. The coated microneedle immunizations were compared to conventional intramuscular hypodermic injections at the same dose in another group of mice.
The researchers found that the microneedle vaccinations induced strong immune responses against influenza virus that were comparable to immune responses induced by the intramuscular, hypodermic immunizations. One month after vaccination, the researchers infected both groups of mice with a high dose of influenza virus. While all mice in a control group of unvaccinated mice died of influenza, all mice in both the hypodermic and the microneedle groups survived.
“Our findings show that microneedle patches are just as effective at protecting against influenza as conventional hypodermic immunizations,” says Richard Compans, PhD, Emory professor of microbiology and immunology and one of the paper’s senior authors. “In addition, vaccine delivery into the skin is desirable because of the skin’s rich immune network.”
Even though cutaneous immunization has been shown to induce a broad range of immune responses, and to be especially effective in individuals over age 60, this method has not been widely used because it has not been convenient and has required highly trained personnel.
"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,” says Mark Prausnitz, PhD, professor in the Georgia Tech School of Chemical and Biomolecular Engineering and co-senior author. “These micron-scale needles can be mass produced using low-cost methods for distribution to doctors’ offices, pharmacies and, possibly, people’s homes.”
Other advantages of the microneedle patches could include more convenient storage, easier transportation and lower dosage requirements. Lower doses could be particularly important because flu vaccine production capacity sometimes is limited for seasonal vaccine, and a future influenza pandemic would require much greater production of vaccine.
Replacing a hypodermic needle with a microneedle patch also could significantly impact the way other vaccines are delivered, and could be particularly beneficial in developing countries. A microneedle patch could fit inside an envelope for delivery by the postal service and would occupy much less storage space. Patches also would increase vaccine safety by reducing the dangers of accidental or intentional hypodermic needle re-use.