TOKYO – Attempts to develop vaccines and treatments for COVID-19 in the form of nasal spray are underway to help fight the spread of the novel coronavirus.
Currently available vaccines are highly effective in preventing the disease from becoming serious, but they don’t offer absolute protection.
As there is fear that much more contagious variants of the virus may spread in the near future, attention is increasingly being focused on finding new medicines that are more effective in preventing infections in addition to those for treating patients who have the disease.
When people receive intramuscular injections of vaccine, the amount of what are known as IgG antibodies usually increases in their blood.
However, only small quantities of IgG antibodies can be found in the membranes of the nose and the throat, to which incoming viruses initially attach. This limits their infection-preventing power.
If another type of antibody known as IgA, which is excreted by membranes, is produced in the nose and the throat, it is possible that infection itself can be prevented to a high degree.
Researchers led by Prof. Tetsuya Nosaka of Mie University, a virologist, and BioComo Inc., a Mie Prefecture-based startup, are jointly developing a nasal spray vaccine to increase IgA antibodies in membranes mainly inside the nose.
The vaccine is produced by inserting genetic material from the novel coronavirus that serves as a blueprint for spikes of the virus into a different virus that is not harmful to humans.
In animal experiments, the vaccine increased IgA antibodies in membranes. When the novel coronavirus was introduced after two doses of the vaccine, almost none of the virus was detected in nasal membranes three days later.
“A nasal spray is less of a physical burden than an injection,” Nosaka said. “We want to start clinical tests within a year.”
HanaVax Inc., a Tokyo-based startup originating from the University of Tokyo, is also working on a nasal spray vaccine, which Shionogi & Co. aims to commercialize.
Overseas, the University of Oxford in Britain and the University of Hong Kong in China have begun clinical tests of a nasal vaccine.
Also, researchers led by Prof. Motoki Takagi of Fukushima Medical University, an expert in drug development science, are developing an infection prevention medicine in a form that involves spraying IgA antibodies directly into the nose.
The researchers succeeded in mass-producing IgA antibodies based on genetic information after extracting the proper kind of antibodies from the blood of people who have been infected with the novel coronavirus.
As a stage prior to the development of infection prevention medicines, they test-produced masks with filters containing IgA antibodies in July. They aim to make the products commercially available in the future.