It’s a crisp Saturday afternoon in late October. You walk outside to check the mail, and discover your package has arrived. Inside is a patch that looks like a Band-Aid. You stick the patch on your arm, hold it down for a few minutes, then peel it off and discard it in the trash.
Congratulations, you’ve just vaccinated yourself against the flu.
In five years or so, this scenario could be a reality. Scientists have developed a “microneedle patch” that makes vaccination so quick and easy it can be done at home. Plus, it’s painless.
Figuring out how to breach the skin's surface without needles was one of the major challenges of developing the patch. Though it's a common belief that much of what we put on our skin gets absorbed into our bloodstream, that's actually not the case. The surface of our skin prevents that from happening.
“The reason why skin doesn’t absorb drugs well is that there’s a very thin layer on the skin called the stratum corneum, only 10 or 20 microns thick,” says Mark Prausnitz, a chemical engineer at the Georgia Institute of Technology who helped lead the research. “If you can get across that barrier, you’re basically in the body.”
Since the stratum corneum is so thin, you don’t need a large needle to penetrate it. So Prausnitz and his team developed a dime-sized patch with 100 tiny microneedles. The microneedles, which are barely visible to the human eye, are made of a mixture of the vaccine and a water-soluble polymer. The patient feels nothing more than the sensation of an adhesive bandage being applied to the skin. But while the patch is on, the microneedles breach the stratum corneum and deliver the vaccine to the more absorbent layers beneath. Then they dissolve. The user can simply toss the patch in the trash, no need for biohazard containers.
The patch has several advantages over traditional needle vaccinations. Obviously, the painlessness is a selling point. But more importantly, the vaccines don't need to be refrigerated. In testing, they’ve remained effective after more than a year, even at temperatures of 100 degrees Fahrenheit. That means they can be sent through the mail. In developed countries like the United States, this would be a convenience for those who don’t have time to visit a pharmacy for their annual flu shot, or for elderly or disabled people who can’t easily travel. But it has even more significant benefits for the developing world.
Most vaccines contain proteins that degrade at room temperature, which is why refrigeration is so important. But the “cold chain” of refrigerated trucks, ships and coolers that keeps vaccines chilled during travel is liable to break down, and many destinations in the developing world don’t have reliable refrigeration to store vaccines once they arrive. As a result, some 40 percent of vaccines are ruined before they can be administered, at a cost of millions of dollars. The patch could change all that.
“Because it can be self-administered, and because it’s temperature stable, you have this great increase in accessibility to lifesaving vaccines,” says Roderic Pettigrew, the Director of the National Institute of Biomedical Imaging and Bioengineering at the National Institutes of Health (NIH), which funded the study. “And all that without pain.”
NIH’s Quantum Grants Program funds projects aiming to make a profound impact on “the prevention, diagnosis, or treatment of a major disease or national public health problem through the development and implementation of biomedical technologies within 10 to 12 years.” The vaccine patch has been tested in a human study, which showed it generated an immune response similar to traditional intramuscular injections. It also showed the patches to be safe, with side effects limited to mild skin reddening and itching. The next step will be a larger trial and application for FDA approval. A paper detailing the research was recently published in the journal The Lancet.
A part of the study looked at how the patch might affect people’s vaccination habits, and was promising as well. More than half of Americans don’t get vaccinated against seasonal flu, though the Centers for Disease Control and Prevention (CDC) recommends the vaccine for everyone over six months old. In the study, some 65 percent of participants said they would get vaccinated if they could do it with a patch.
Now, researchers are also working in conjunction with the World Health Organization and the CDC to develop a patch to vaccinate against polio, and one to vaccinate against measles and rubella, all scourges in the developing world. Human trials are expected to start next year. Researchers hope all the patches will be approved and ready for use in five years. And there’s no reason to believe that any vaccine currently on the market could not be delivered in patch form, Prausnitz says. The team has tested a dozen different vaccines in animal trials, and all have been effective.
Vaccine patches could be especially helpful in the case of global health emergencies like a flu pandemic, where there’s a sudden need for hundreds of thousands or even millions of vaccines in every corner of the world.
“In that kind of situation, the patch could be very helpful, as it could be disseminated very quickly and easily,” Prausnitz says.
One potential challenge in developing other vaccine patches may be dealing with adjuvants, which are substances sometimes added to vaccines (though generally not the flu vaccine) to boost the immune response, making it possible to use a lesser dose of the vaccine antigen. Most adjuvants are not compatible with the microneedle patch, Prausnitz says. It may turn out not to be an issue – skin-delivered vaccines may give a stronger immune response than intramuscular vaccines, making adjuvants unnecessary. If not, it may be necessary to use a higher dose of vaccine antigens in the patches than in the injections, or to develop different adjuvants that can be used in patch form. But researchers are optimistic that challenges can be overcome. And they say the patch will likely be cheaper than traditional vaccination, since there’s no need for refrigeration or for medical professionals.
“It would be huge, transformative,” Pettigrew says. “Indeed, this is a wonderful example of how technological innovation can improve our lives in general, and in this case how it can improve the health of all of us.”