TOKYO – Attempts are being made to develop vaccines and treatments for COVID-19 in the form of nasal sprays to combat the spread of the novel coronavirus.
Currently available vaccines are very effective in preventing the disease from getting serious, but they do not offer absolute protection.
Since it is to be feared that much more contagious variants of the virus could spread in the near future, the focus is increasingly on finding new drugs that, in addition to those used to treat sick people, also prevent infections more effectively.
When people receive intramuscular vaccinations, the amount of antibodies called IgG in their blood usually increases.
However, only small amounts of IgG antibodies are found in the mucous membranes of the nose and throat, to which incoming viruses initially attach. This limits their anti-infection power.
If another type of antibody called IgA is formed in the nose and throat and is excreted through membranes, an infection itself can be largely prevented.
Researchers led by Prof. Tetsuya Nosaka of Mie University, a virologist, and BioComo Inc., a startup based in Mie Prefecture, are jointly developing a nasal spray vaccine to increase IgA antibodies in membranes, primarily in the nose.
The vaccine is made by inserting genetic material from the novel coronavirus, which acts as a blueprint for virus spikes, into another virus that is not harmful to humans.
In animal studies, the vaccine increased IgA antibodies in membranes. When the novel coronavirus was introduced after two doses of the vaccine, almost no virus was detected in the nasal mucous membranes three days later.
“A nasal spray is less stressful than an injection,” says Nosaka. “We want to start clinical tests within a year.”
HanaVax Inc., a Tokyo-based startup from the University of Tokyo, is also working on a nasal spray vaccine that Shionogi & Co. plans to commercialize.
Overseas, the University of Oxford in the UK and the University of Hong Kong in China have started clinical trials of a nasal vaccine.
In addition, researchers under the direction of Prof. Motoki Takagi of Fukushima Medical University, an expert in drug development, are developing an infection prevention drug in a form in which IgA antibodies are sprayed directly into the nose.
Researchers successfully mass-produced IgA antibodies based on genetic information after extracting the correct antibodies from the blood of people infected with the novel coronavirus.
As a preliminary stage in the development of drugs to prevent infection, they tested masks produced in July with filters that contain IgA antibodies. The aim is to make the products commercially available in the future.