A study conducted in animals and published in the Proceedings of the National Academy of Sciences suggests that the immune response from a vaccine patch is 10 times greater than delivery into the arm muscle via needle.
Vaccine patches could offer a new way to deliver vaccines with the benefits of being painless, less invasive than a shot, offering the opportunity for self-administration, and without needing cold storage.
Furthermore, heightened immune responses could lead to dose sparing, requiring smaller doses of vaccine, as well as boosting vaccination rates thanks to the ease of use.
3D printing: answer to the challenges of microneedle fabrication?
While vaccines are typically administered as injections into the muscle or subcutaneous space, there is increasing interest in the intradermal route, as human skin is rich in immune cells. Intradermal vaccination, however, still requires trained medical personnel; as well as being painful and difficult to administer.
Consequently, researchers have turned their attention to microneedles – micrometer-sized solid needle projections that can painlessly puncture the stratum corneum and deliver therapeutics into the epidermis/dermis.
A vaccine patch consists of a polymer patch with vaccine-coated microneedles: and in applying it directly to the skin, it can target immune cells.
While microneedle patches have been studied for decades, challenges have been difficult to overcome: it’s hard to adapt microneedles to different vaccine types; while there are sizeable challenges in the manufacturing process.
Most microneedles are made with master templates to make molds: however, the molding of microneedles is not very versatile, and drawbacks can include reduced needle sharpness during replication.
Such are the challenges that “arguably, the field of microneedles needs a breakthrough in fabrication approaches to fully unlock the potential of microneedles to address a number of drug and vaccine delivery needs,” note the researchers.
Pre-clinical study results show the immune response from the vaccine patch were 10 times greater than a needle vaccine.
Furthermore, the patch generated a T-cell and antigen-specific antibody response that was 50 times greater.
They hope their new tech can provide the answer. The microneedles were produced at the University of North Carolina at Chapel Hill using a CLIP prototype 3D printer invented by Joseph M. DeSimone, professor of translational medicine and chemical engineering at Stanford University and professor emeritus at UNC-Chapel Hill. They are produced by CARBON, a Silicon-Valley company he co-founded.
“Our approach allows us to directly 3D print the microneedles which gives us lots of design latitude for making the best microneedles from a performance and cost point-of-view,” lead study author Shaomin Tian, researcher in the Department of Microbiology and Immunology in the UNC School of Medicine, explained.
Such microneedles can also be easily customized to develop various vaccine patches for flu, measles, hepatitis or COVID-19 vaccines – addressing another previous challenge.
The patch was tested with subunit vaccines; but the scientists are continuing their research by formulating mRNA vaccines – such as Pfizer and Moderna’s COVID-19 vaccines – into patches for future testing.
Getting a vaccine typically requires a visit to a clinic, hospital or vaccination center: requiring a health care provider to take a vacine from a refrigerator; fill a syringe with the liquid vaccine formulation; and inject it into the arm.
“Although this process seems simple, there are issues that can hinder mass vaccination – from cold storage of vaccines to needing trained professionals who can give the shots," note the researchers.
“Meanwhile vaccine patches, which incorporate vaccine-coated microneedles that dissolve into the skin, could be shipped anywhere in the world without special handling and people can apply the patch themselves.”