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Low Cost Vaccine, Patch Device Produce Immune Responses

Vaccine patch

High density microarray patch (Vaxxas, Univ. of Queensland)

3 June 2021. Tests with lab mice show one dose of a lower cost Covid-19 vaccine given with a needle-free patch generates strong antibody and cellular immune responses. Researchers from University of Queensland in St. Lucia, Australia report their findings of the HexaPro vaccine with a high-density microarray patch that appear this week on the BioRxiv preprint server and are not yet peer-reviewed.

Vaccines have become a key weapon against the Covid-19 pandemic, and where widely administered, they reduce infections, hospitalizations, and deaths. Today’s Covid-19 vaccines are made with advanced biotechnology processes, such as synthetic messenger RNA, given by injection, which in most cases require two doses. Current vaccines also require deep refrigeration or freezing from their manufacturing sites to injection, which limits their shelf life and raises distribution costs. Maintaining this so-called cold chain is difficult to achieve in some lower resource regions of the world.

A team at University of Texas in Austin and Mount Sinai medical center in New York is developing a lower-cost Covid-19 vaccine designed to be more easily manufactured, transported, and administered. The HexaPro vaccine uses a synthetic protein resembling the protein on the surface of the SARS-CoV-2 coronavirus spike, to generate a protective response from the immune system, including antibodies and T-cells, against six variations of the protein. But HexaPro is also designed to be produced in eggs, an inexpensive manufacturing process similar to flu vaccines used for seven decades, to reduce the final cost of the vaccine to health authorities.

Easy painless vaccine administration

In addition, the vaccine is less heat-sensitive and more stable than many other Covid-19 vaccines, requiring normal refrigeration, 2 to 8 degrees C (35 to 46 F). Vaxxas, in Brisbane, Australia and spun-off from Queensland university labs, develops high-density microneedle patches or HD-MAPs for administering vaccines, a technology that allows vaccines to be stored at ambient temperatures. Each nine-millimeter square patch contains micro-scale needles coated with a dry form of the vaccine that remains stable for 30 days in temperatures reaching 25 degrees C (77 F). In addition, Vaxxas uses an applicator device for easy painless administration of the vaccine, or even self-administration, without syringes that can frighten recipients.

Researchers led by Queensland’s David Muller, a research fellow in chemistry and molecular biology, tested the HexaPro vaccine administered with an HD-MAP in lab mice engineered to express Covid-19 infections and human immune responses. The mice were given the vaccine with HD-MAPs in one or two doses, as well as with or without an adjuvant to boost the immune response. Likewise, comparable doses were given to mice through intradermal syringe injections, with both vaccination methods compared to unvaccinated mice. The mice were then given SARS-CoV-2 viruses through the nose. After six days, blood and tissue samples from their lungs and brains were collected.

The results show a two doses of HexaPro or a single dose of HexaPro with an adjuvant, given either with HD-MAPs or injections, stops Covid-19 infections in mice, which show no sign of virus in their lungs or brains. Blood samples show, however, that a single dose of HexaPro and adjuvant given with an HD-MAP produce strong and broad immunoglobulin G and T-cell responses that protect against the B.1.1.7 and B.1.35.1 variants, first discovered in the U.K. and South Africa respectively, exceeding the immune responses of mice given the vaccine with intradermal injections.

“We designed this research to address the serious on-going need to improve the global vaccination efforts against COVID-19 and future pandemics,” says Muller in a Vaxxas statement released through BusinessWire. “Based on our results, we believe that Vaxxas’ HD-MAP could offer a compelling solution that importantly could use less vaccine and potentially could be readily distributed without refrigeration for self-administration.”

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