Needle-free COVID-19 vaccine proves to be a promising alternative to jabs

High-density microarray patch (HD-MAP). Credit: University of Queensland.

Researchers in Australia have developed a needle-free COVID-19 vaccine in the form of a patch that slowly releases the serum through the skin. This type of vaccine delivery is not only painless, but studies in mice also showed that the generated immune response against coronavirus was actually stronger than the dot.

The high-density microarray patch (HD-MAP) is the result of a collaboration between Brisbane-based biotechnology firm Vaxxas and the University of Queensland. The patch does not deliver an mRNA serum, like the popular Pfizer / BioNTech and Moderna. Instead, it was tested on a more affordable vaccine candidate developed by the University of Texas, called Hexapro.

The hexapro vaccine uses a stabilized version of the surface protein of the coronavirus to train the human immune system to recognize and fight infection when the right virus is encountered. The manufacturing process is largely the same as for the flu vaccine. The serum is made in eggs and can be stored at a standard refrigerator temperature of 2 to 8 degrees Celsius, making the shot affordable and accessible to virtually any part of the globe. Hexapro is currently undergoing clinical trials in Vietnam, Thailand and Brazil.

Dr. David Muller of the University of Queensland’s Department of Chemistry and Molecular Life Sciences wanted to take this vaccine to the next level. He and colleagues have developed HD-MAP, which they believe could be a “game-changer for vaccine delivery in a pandemic environment.”

Tests on mice showed that the patch the size of a fingertip produced strong immune responses that were effective in protecting the mice from infection with the virus causing COVID-19. This includes the highly contagious and more dangerous varieties in the UK and South Africa.

Using patches instead of needle delivery has several significant benefits. Once the patch is applied to the patient’s shoulder or other body part, more than 5,000 microscopic protrusions deliver the serum into the skin. The application of the patch does not cause pain or any discomfort, unlike vaccine needles, which many people abhor. It is easy to use, which means that there is no need for highly trained medical staff, and patients can carry out the vaccination themselves.

Once the patches are dry coated, they remain stable for at least a month at 25 degrees Celsius and a week at 40 degrees Celsius. It is very useful in environments where the cold storage infrastructure is lacking. Healthcare professionals can take millions of these patches and then have enough time to distribute them across rural and remote areas that may lack electricity or mobile cold rooms.

In addition, the results of the study suggest that the patch delivery produces a stronger immune response than the needle-based one.

Dr. David Muller keeps the vaccine patch in the packaging. Credit: University of Queensland.

“Traditional intramuscular injection goes deep into the muscle where there are not many immune cells. Using the patch, we are able to accurately target the layers of the skin that have a high density of immune cells. This results in a much more efficient vaccine uptake and corresponding immune response. This vaccine works by targeting the body’s immune response (antibodies) to the tip protein on the surface of the virus. In short, we dry coat the tip protein on thousands of small protrusions of 250 µm in length. This coated vaccine patch is applied to the skin, which deposits the vaccine in the dermal layers of the skin, which are rich in immune cells. This precise delivery of the vaccine to the immune cells results in a very strong immune response to SARS-CoV-2, ”said Dr. Muller. ZME Science.

What is left now is to validate these findings in humans. The researchers are planning a phase I clinical trial with the patch in the second quarter of 2022.

“This will initially be designed around ‘booster’ dosing,” said Dr. Muller.

The results were shown in the journal The progress of science.

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