Researchers at the University of Tokyo Pandemic Preparedness, Infection and Advanced Research Center (UTOPIA) have announced successful animal testing of a novel nasal COVID-19 vaccine that demonstrates superior respiratory tract immunity compared to existing mRNA vaccines. The research team, led by UTOPIA Director Yoshihiro Kawaoka, published their findings in Nature Communications, highlighting the vaccine's potential to prevent both serious illness and viral transmission.
Novel Vaccine Design Addresses Current Limitations
The new vaccine addresses a critical gap in current COVID-19 vaccination strategies. While mRNA vaccines have been widely deployed since the pandemic's onset, there has been growing demand for vaccines that boost immunity specifically in areas where infection occurs, such as the upper respiratory tract, and which can inhibit viral spread even when infection occurs.
The research team engineered viruses using genetic information from which the coronavirus genes needed to assemble viral particles were removed. These modified viruses create immunity-inducing proteins inside human and other cells but cannot build viral structures or core components themselves, eliminating any risk of multiplication and spread.
Superior Lung Immunity Demonstrated
When administered nasally to mice, the vaccine achieved immunity on the mucous membranes of both nasal cavities and lungs. Notably, the new vaccine reportedly achieves particularly wide immunity coverage in the lungs when compared to mRNA vaccines, representing a significant advancement in respiratory tract protection.
Hamster Studies Show Viral Suppression
The efficacy testing involved eight hamsters treated with the nasal vaccine, which were subsequently infected with both the delta variant of coronavirus and omicron's XBB subvariant. The results demonstrated complete prevention of viral propagation in the lungs for both variants.
In the nasal cavities, approximately half of the hamsters showed no viral growth by the third day after infection. Even in the remaining hamsters, viral growth was significantly suppressed and disappeared entirely by the sixth day post-infection.
Clinical Implications and Future Potential
Kawaoka emphasized the vaccine's unique advantages, stating, "The nasal vaccine is effective for respiratory tract infections and is thought to be effective in preventing the spread of infection. Unlike mRNA vaccines, it has the advantage of providing immunity similar to that acquired through actual viral infection."
This approach represents a potential paradigm shift in COVID-19 vaccination strategy, as the nasal administration route could provide enhanced protection at the primary site of viral entry and replication. The research team claims that beyond preventing serious illness, the nasal vaccine is expected to prevent infection spread by inhibiting viral growth in the nose, addressing a key limitation of current vaccination approaches.
