26-05-2025
New nasal COVID vaccine offers high immunity in animal tests: Tokyo researchers
TOKYO -- A new type of coronavirus vaccine administered nasally has proven effective when tested on animals, researchers at the University of Tokyo Pandemic Preparedness, Infection and Advanced Research Center (UTOPIA) have announced.
The research team including UTOPIA Director Yoshihiro Kawaoka claim that in addition to preventing serious illness, the nasal vaccine is expected to prevent the spread of infection by inhibiting growth of the virus in the nose.
Since the global outbreak of COVID-19, vaccines using messenger RNA (mRNA), which contains genetic information, have been developed and put into widespread use for inoculations. However, there has been demand for new types of vaccines that boost immunity in areas where infection occurs, such as the upper respiratory tract, and which inhibit the spread of the virus even if infection occurs.
The team created viruses using genetic information from which the parts of the coronavirus' genes needed to assemble viral particles were removed. Inside human and other cells, these engineered viruses create proteins needed for acquiring immunity. Because they cannot build the viral structure or core components themselves, there is no risk of them multiplying and spreading.
When a vaccine with the artificial virus was administered nasally to mice, immunity was achieved on the mucous membranes of their nasal cavity and lungs. The new type reportedly achieves particularly wide immunity coverage in the lungs when compared to mRNA vaccines.
Next, when a group of eight hamsters treated with the nasal vaccine was infected with the delta variant of the coronavirus and omicron's XBB subvariant, neither of these virus variants propagated in the lungs. The nasal cavities of around half of the hamsters were reportedly free of viral growth on the third day after infection, and even in the other half, the amount of growth was significantly suppressed, disappearing by the sixth day.
Kawaoka commented, "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."
The results were published in the U.K. science journal Nature Communications.
