Nearly 72% of the world’s population have received the injectable vaccines to fight COVID-19, but they must take a booster injection every year or more frequently. A team of researchers led by Krishnendu Roy, Bruce and Bridgitt Evans Dean of the School of Engineering and University Distinguished Professor at Vanderbilt University, is aiming to change that.
The group has developed a promising intranasal nanovaccine that boosts the immune system in mice against the strain of coronavirus that causes COVID-19 and may one day do the same in humans. The research was published this month in Advanced Science. Roy is the Principal Investigator of the study, and the research was conducted in Roy’s lab during his time at Georgia Institute of Technology.
According to researchers, monthly death rates from COVID-19 in the United States remain well over 1,000 four years after the start of the pandemic in 2020.
Even after vaccination with booster doses, there are asymptomatic, symptomatic, and some severe cases of infection observed as soon as a few months. These results indicate declining antiviral immunity within a short period and raise questions about durable efficacy and protection through the current vaccines, according to researchers. The limited efficacy of approved vaccines to prevent sunsequent infection is due to several factors, one being poor immunity in the mucosal surfaces that line the body’s respiratory system – the sites of virus entry. The researchers said there is a critical need for new mucosal vaccine strategies that achieve high levels of durable protection against infection, while also mitigating post-COVID complications such as long COVID.
The goal of the Roy group was to study if an intranasal version of the vaccine can work as the booster after receiving the intramuscular vaccines. The answer, researchers said, is yes—in mice. The team developed a version of the SARS-CoV-2 vaccine that uses a newly designed synthetic polymer-lipid nanoparticle and the recombinant spike protein of the virus. The combination facilitated a strong and balanced immune response, both in the blood and particularly in the lung, generating both mucosal antibodies and T cell responses, according to the researchers.
“Our preclinical study demonstrates that the mucosal route is essential for new vaccination strategies and should be included in the next generation of immunization protocols against SARS-Cov-2 and other emerging respiratory infectious diseases,” Roy said. “Several groups are working on a nasal spray-based vaccine strategy. But we wanted to study whether a nanovaccine with specific adjuvants and the viral spike protein can be delivered both as an intramuscular injection and then as a intranasal innoculation to generate strong immunity in the lung.”
In addition to his role as Dean of the School of Engineering, Roy is also University Distinguished Professor of biomedical engineering, chemical and biomolecular engineering, and pathology, microbiology and immunology.