Making Vaccines Easier With Microneedles (Archive)
Originally posted March 11, 2018.
Rachel Creighton is a graduate student in bioengineering. She is developing a dissolving microneedle patch to deliver vaccines into the cheek, and am studying how changes in the geometry and materials of the microneedles can make the vaccine better at preventing infection.
It’s a sunny Tuesday morning when you walk into your doctor’s office for your yearly physical exam. While your doctor checks your blood pressure and listens to your heart rate, you’re preoccupied daydreaming about the burrito you plan on eating for lunch. You’re just trying to decide whether you should pay extra for guacamole when you hear the words:
Immediately your palms get sweaty, your heart starts racing, and you feel like you might pass out. You no longer care that it’s a beautiful day and you can’t even think about food anymore. You’re body has gone into total panic mode because of the thought of one tiny object: a needle.
If this scenario is all too familiar, you are not alone. Doctors estimate up to 10% of the population has a phobia of needles.  And while it may seem trivial, needle phobia is a real problem that causes people to avoid seeking medical care.  This can be a really serious problem for people who rely on drugs administered by needles, like diabetics who need insulin to manage blood sugar levels.
While there are many reasons that people fear needles, one primary reason is the pain associated with the needle. In one study, researchers found that 7% of adults did not receive the flu vaccine primarily because of fear of the needle.  In the same study, 30% of adults said they would be more willing to receive the flu vaccine if it was not painful. This study and others like it suggest uptake of vaccines (and acceptability of injected therapies) could be significantly improved if there were alternate modes of delivery that were less painful than traditional needles.
Some drugs and vaccines need to be injected because if they were delivered in a pill, the drug would be digested in the stomach or it would not be absorbed very efficiently in the intestine.  Researchers are working on ways to overcome these barriers to delivery in the digestive system, but there is another approach too. What if we could just re-design the needles so that they could deliver things beneath the skin but they weren’t painful anymore?
Many scientists have been working on this for many years and they have come up with a new type of needle called a microneedle. Many microneedles can be integrated into a patch that might look like a Band-Aid. You would just apply this patch to your skin, and the microneedles would deliver a wide range of drugs and vaccines. These needles are so tiny that they don’t reach the pain receptors in your skin, meaning they don’t cause any pain. They also don’t reach the blood vessels in your skin, so they don’t cause any bleeding.  Depending on their size, an array of microneedles might look and feel like really coarse sandpaper or Velcro.
Microneedle technology could be a reality in the near future. Just last summer, researchers from Emory University and the Georgia Institute of Technology published the results of a clinical trial to evaluate the safety of a flu vaccine delivered via microneedles.  The trial demonstrated that the microneedles caused less pain and soreness compared to traditional injections. Even better, the researchers found that the immune responses were similar between people who received the microneedle vaccine and those who received the traditional injection.
More clinical trials are needed to further evaluate the efficacy of this microneedle vaccine, but this trial represents a leap forward for microneedle technology. Hopefully in the near future, more trials will be conducted to evaluate microneedles for delivery of other vaccines and drugs. And maybe with the help of microneedles, doctor appointments can soon be a little less of a pain.
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 Wright, S., Yelland, M., Heathcote, K., Ng, S. K. & Wright, G. Fear of needles–nature and prevalence in general practice. Aust Fam Physician 38, 172-176 (2009).
 Taddio, A. et al. Survey of the prevalence of immunization non-compliance due to needle fears in children and adults. Vaccine 30, 4807-4812, doi:10.1016/j.vaccine.2012.05.011 (2012).
 Vela Ramirez, J. E., Sharpe, L. A. & Peppas, N. A. Current state and challenges in developing oral vaccines. Adv Drug Deliv Rev 114, 116-131, doi:10.1016/j.addr.2017.04.008 (2017).
 Kim, Y. C., Park, J. H. & Prausnitz, M. R. Microneedles for drug and vaccine delivery. Adv Drug Deliv Rev 64, 1547-1568, doi:10.1016/j.addr.2012.04.005 (2012).
 Rouphael, N. G. et al. The safety, immunogenicity, and acceptability of inactivated influenza vaccine delivered by microneedle patch (TIV-MNP 2015): a randomised, partly blinded, placebo-controlled, phase 1 trial. Lancet390, 649-658, doi:10.1016/S0140-6736(17)30575-5 (2017).