Australian Researchers Develop Pan-Coronavirus Vaccine Candidate with 99.9% Protection Against Multiple Variants
Key Insights
Researchers at the Centenary Institute (search) and University of Sydney have developed CoVEXS5 (search), a novel COVID-19 (search) vaccine candidate that reduced viral levels in infected mice by 99.9% compared to unvaccinated controls.
The vaccine uses a fusion-based spike protein (search) design incorporating elements from multiple coronaviruses to provide broad protection against current variants including Omicron XBB.1.5 (search) and SARS-CoV-1 (search).
CoVEXS5 (search) incorporates Sepivac SWE (search), an open-access adjuvant that eliminates licensing restrictions and reduces production costs, potentially improving global vaccine equity.
Researchers at the Centenary Institute (search) and the University of Sydney have developed a promising COVID-19 (search) vaccine candidate that demonstrates exceptional protection against multiple coronavirus variants, including the highly immune-evasive Omicron XBB.1.5 (search) strain. The vaccine, named CoVEXS5 (search), reduced viral levels in the lungs of infected mice by approximately 99.9% compared to unvaccinated animals, according to findings published in the journal npj Vaccines.
The development comes as Australia continues to face COVID-19 (search) transmission during the winter season, with new Omicron subvariants contributing to rising infection and hospitalization rates. As of 2025, more than 115,000 COVID-19 cases have been reported to the Australian Government's National Notifiable Diseases Surveillance System.
Novel Fusion-Based Design Targets Multiple Coronaviruses
CoVEXS5 (search) employs a unique approach by incorporating a novel spike protein (search) engineered through fusing elements from several different coronaviruses into a single structure. This fusion-based design aims to train the immune system to recognize and respond to a wider spectrum of coronaviruses, rather than targeting just one specific strain.
"By combining parts of multiple coronaviruses, we've created a vaccine that can better prepare the body to fight off both current and future threats," said Dr. Claudio Counoupas, co-lead study author and researcher at the Centenary Institute (search)'s Centre for Infection & Immunity.
In laboratory testing, the vaccine candidate protected mice from multiple coronaviruses, including both the Omicron XBB.1.5 (search) variant and SARS-CoV-1 (search), the virus responsible for the 2002-2004 SARS outbreak and a close relative of SARS-CoV-2 (search). The vaccine also generated strong immune responses, including high levels of virus-neutralizing antibodies and the activation of specialized lung T-cells that play a critical role in protecting against respiratory infections.
Broad Immune Response and Cross-Variant Protection
Elizabeth Chan, a Ph.D. student at the Centenary Institute (search) and the University of Sydney and co-lead author, noted that the findings point to the possibility of a next-generation COVID-19 (search) vaccine capable of offering cross-variant protection. "The immune response we saw in the laboratory was both strong and broad. It's exciting to think that this approach could help future-proof vaccines against ongoing changes in the virus," she said.
The vaccine candidate's ability to provide protection against both current variants and future emerging threats represents a significant advancement in pandemic preparedness strategies. By broadening the immune response beyond a single strain, CoVEXS5 (search) may offer more durable protection as the virus continues to evolve.
Open-Access Adjuvant Enhances Global Accessibility
CoVEXS5 (search) incorporates Sepivac SWE (search), an open-access adjuvant that boosts the immune response while offering practical advantages for vaccine manufacturing and global distribution. According to senior study author Professor Jamie Triccas, Deputy Director of the Sydney Infectious Diseases Institute, Sepivac SWE provides additional benefits by eliminating licensing restrictions and reducing production costs.
"Sepivac SWE (search) is not only effective, but because it's open-access, it can be used by manufacturers around the world without licensing barriers or high costs," Triccas explained. "That's a huge advantage for global vaccine equity, especially in low and middle-income countries where access and cost are critical concerns."
The work was funded by the Coalition for Epidemic Preparedness Innovations (search), a global partnership focused on accelerating the development of vaccines against epidemic and pandemic threats while ensuring accessibility. The research team is now focused on advancing the vaccine candidate through further development and testing for future use.