SINGAPORE: A team of scientists led by Duke-NUS Medical School have discovered a potential intranasal vaccine candidate demonstrating enhanced and longer-lasting immunity against SARS-CoV-2 viruses compared to traditional injection methods.

The findings, published in the journal eBioMedicine, highlight the potential of this intranasal route to reduce the need for booster shots and enhance overall protection against the virus.

The research delved into the effectiveness of intranasal administration versus subcutaneous injection of the vaccine. The results demonstrated that intranasal delivery triggered a robust mucosal antibody response and, more significantly, improved long-term mucosal and systemic immune protection by promoting the production of airway-resident T cells and central memory T cells.

Associate Professor Ashley St John, lead author of the study and a member of Duke-NUS’ Emerging Infectious Diseases Programme, explained, “Our data show that, compared to subcutaneous vaccination, the intranasal route improved the response of certain immune cells, known as T cells, which reduced disease severity. Not only that, but it also resulted in a greater number of T central memory cells compared to subcutaneous vaccination, which could lead to longer-lasting protection.”

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The crucial role played by T central memory cells in retaining long-term immunity implies a potential reduction in the frequency of booster shots required for continued protection. This groundbreaking research suggests that intranasal vaccination could be a game-changer in the ongoing battle against COVID-19.

The study also investigated the impact of adjuvants, substances added to vaccines to enhance immune responses. Researchers found that different adjuvants influenced the characteristics of T cells, their activation, and the production of cytokines, providing valuable insights into optimizing vaccine formulations.

Furthermore, the research team discovered that the intranasal vaccine induced a more effective response from a type of antibody called IgG, circulating in the bloodstream. This heightened immune response proved more effective in neutralizing variants of the virus, including newly emergent ones. These findings underscore the potential of intranasal vaccines in providing comprehensive protection against evolving strains of the virus.

Professor Patrick Tan, Senior Vice-Dean for Research at Duke-NUS, emphasized the significance of the study, stating, “While the acute phase of the pandemic may be behind us, the rise of new variants…demonstrates that we have room in our arsenal of vaccines and treatments for even better tools.” He highlighted the promise of mucosal vaccination in improving COVID-19 vaccine efficacy with potentially fewer boosters needed.

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To capitalize on this groundbreaking discovery, a patent has been filed covering the vaccine composition formulated for mucosal delivery. This move opens the door for potential industry partnerships aimed at developing mucosal vaccines not only for COVID-19 but also for other pathogens targeting mucosal surfaces.

As the scientific community continues to adapt to the evolving landscape of the pandemic, this intranasal vaccine candidate presents a hopeful avenue for achieving long-term immunity and reducing the global burden of COVID-19.