A Flu Vaccine without the Needle

A new technology delivers a vaccine in a painless, biodegradable skin patch.

Getting vaccinated for the flu or other infections could become as easy as pressing a patch onto the skin–no shot in the arm required

No needle: Microneedles made of a polymer that dissolves in body tissues can be used to deliver vaccines directly and painlessly into the skin. The microneedles shown here, inserted into pig skin, dissolve in a matter of minutes.

A new paper published in Nature Medicine describes a patch that holds an array of microneedles that administer a vaccine and dissolve painlessly. That could make it possible for people to get inoculated more easily and even administer their own vaccines.

Most vaccines are delivered by an injection into muscle. But Mark Prausnitz, lead author of the paper and a chemical and biological engineer at Georgia Institute of Technology, says that the surface of the skin could be a better entry point. Because the body expects to encounter harmful invaders on its surfaces, the skin is loaded with cells that can launch an immune response–a key step for a vaccine to work.

Researchers have investigated other microneedle patches as a way to deliver drugs. This version, a collaboration between the labs of Prausnitz and Richard Compans, a microbiologist at Emory, adds an innovation: The needles are constructed out of a polymer that dissolves in bodily fluids. Just several hundred micrometers in length, the needles can penetrate the outer layers of the skin before melting away in a few minutes. As they do so, a vaccine encapsulated in the needles travels into the skin. Only a thin biodegradable backing is left behind, and it washes away in water.

Researchers tested the patches on mice and found that the animals that received the flu vaccine by skin patch could fight off an infection 30 days later just as well as mice that had received an injection. Furthermore, mice vaccinated through the skin had a much lower level of virus in their lungs, suggesting that the patch could provoke a more effective immune response.

Prausnitz and his collaborators are seeking funding for a clinical trial of the influenza vaccine patch in humans. They are also investigating the possibility of using a similar system for other types of infectious diseases.

Samir Mitragotri, a chemical engineer at the University of California, Santa Barbara, says that the work is “highly innovative,” and that the dissolving microneedles solve two important problems in immunization: They are painless, and they avoid the need to dispose of medical waste.

Bruce Weniger, a flu vaccine researcher at the Centers for Disease Control and Prevention, adds that the patches would be less invasive for patients and easier to deliver to remote populations. As such, they could help make vaccination campaigns easier in developing countries. But Weniger adds that economics may get in the way of replacing existing vaccine shots with patches.

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