Patch takes the ‘ouch’ out of flu vaccines

EMORY (US)—Flu vaccine delivered through microneedle skin patches is just as effective at preventing influenza in mice as immunization by hypodermic needle, researchers at Emory University and the Georgia Institute of Technology find.

The new patch method of delivering flu vaccine could improve overall seasonal vaccination coverage in people because of decreased pain, increased convenience, lower cost, and simpler logistics over conventional hypodermic immunization.

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 into 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 comparable to responses induced by injection immunizations. One month after vaccination, the researchers infected both groups of mice with a high dose of influenza virus. While all the mice in the control group of unvaccinated mice died of influenza, all the 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, Emory professor of microbiology and immunology. “In addition, vaccine delivery into the skin is desirable because of the skin’s rich immune network.”

The microneedle patches could also be more easily stored and transported and could require lower doses—particularly important because seasonal flu vaccine production capacity is at times limited,  and a future influenza pandemic would require greater vaccine production.

Replacing a hypodermic needle with a microneedle patch also could significantly affect the way other vaccines are delivered, and could be particularly beneficial in developing countries. A microneedle patch fits inside an envelope for postal delivery and occupies less storage space. Patches also reduce the dangers of accidental or intentional hypodermic needle re-use.

The Emory and Georgia Tech research team began developing the patch technology in 2007 with grants from the National Institutes of Health. The team plans future immunization studies in other animals, including guinea pigs or ferrets, before initiating human studies.

The research was recently published in the Proceedings of the National Academy of Sciences.

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