There are 14 under study and 2 already approved. How do they differ from the injectable immunization that has been applied around the world since late 2020 and why experts insist on its need in the face of the pandemic.
The doses of vaccines developed against covid are still effective in reducing the risk of complications and deaths if people are exposed to SARS-CoV-2 and become infected. They are given as an injection in the arm. But progress is also slowly being made in the development of nasal vaccines, which are aimed more at preventing infection. In other words, try to reduce the risk of people getting infected.
Nasal doses have been thought of as a vaccination strategy that provides long-term immunity.. During 2022, 14 covid nasal vaccines were evaluated in clinical trials, according to the World Health Organization.
There are also other candidate vaccines in preclinical trials, such as in the case of Argentina and the United States. In some, such as India and China, they have already been licensed for emergency use.
Vaccines that can be administered mucosally through the mouth or nose are developed from this approach. Mucous secretions are wanted to produce IgA antibodies. There was already this type of flu vaccine, which is administered through the nose.. So nasal covid vaccines could be a more accessible alternative to injections for needle-averse patients.
According to Michael Russell, professor emeritus of microbiology and immunology at the University of Buffalo, vaccines applied to the mucous membranes have advantages. “The best way to protect a person from covid is to block the virus at its point of entry, or at least confine it to the upper respiratory tract, where it can do relatively little harm,” he wrote.
It is believed that if nasal vaccines generate IgA antibodies, the coronavirus could be neutralized and thus reduce its transmissibility. In contrast, current vaccinations do not induce IgA antibody responses.
Scientist Akiko Iwasaki’s team tested a nasal vaccine on hamsters and mice in the United States.
One of the developments under study is underway at Yale University in the United States. According to scientist Akiko Iwasaki during a webinar organized by the International Union of Immunology Societies, the nasal vaccine that she is studying with her team could be used as a booster dose. It would allow “robust immune induction in the nasal cavity, as well as the lower respiratory tract, by establishing resonant memory cells in the tissues.”
In the study, researchers administered the nasal vaccine to mice and hamsters. They have had promising results and the next step will be to test the efficacy and possible toxicity of the vaccine in non-human primates, which may take approximately 6-12 months.
Research into another nasal vaccine is also underway in Australia, which has received a grant of almost a million dollars. It will be held at the Centenary Institute and the University of Sydney. Lead researcher Professor Warwick Britton said new vaccination strategies were urgently needed.
“Although the approved vaccines substantially reduce the severity of the disease and hospitalization, there is little evidence that they block virus transmission, especially in the case of newly emerging variants,” he said.
“That’s because current intramuscular vaccines don’t stimulate the production of virus-neutralizing antibodies or T cells in the nasal cavity and respiratory tract, places where infection starts in the body,” he explained. A key part of the research will be the development of a stable dry powder form of the vaccine to facilitate nasal administration.
