The emergence of COVID-19 variants such as delta and omicron have sent scientists scrambling to determine whether existing vaccinations and boosters are still effective against new strains of SARS-Cov-2.
In a new study from Yale, researchers found a new response to the rapidly mutating virus might be found right at the door to our lungs.
They found that intranasal vaccination provides broad-based protection against heterologous respiratory viruses, while so-called systemic immunization, which uses an injection to elicit body-wide protection, did not.
Mucous membranes contain their own immune defense system that combat air- or foodborne pathogens. When challenged, these barrier tissues produce B cells which in turn secrete immunoglobin A (IgA) antibodies.
Unlike vaccines which elicit a system-wide immune response, IgA antibodies work locally on mucosal surfaces found in the nose, stomach, and lungs.
In the study, the team wondered if triggering IgA response might also produce a localized immune response against respiratory viruses.
They tested a protein-based vaccine designed to jump-start an IgA immune response, administering it to mice through injections, as is commonly done with systemic immunizations, and also intranasally.
They then exposed mice to multiple strains of influenza viruses.
They found that mice that had received vaccine intranasally were much better protected against respiratory influenza than those that received injections.
Nasal vaccines, but not the shot, also induced antibodies that protected the animals against a variety of flu strains, not just against the strain the vaccine was meant to protect against.
The team is currently testing nasal vaccine strains against COVID strains in animal models.
While both vaccine injections and nasal vaccines increased levels of antibodies in the blood of mice, only the nasal vaccine enabled IgA secretion into the lungs, where respiratory viruses need to lodge to infect the host.
If the nasal vaccines prove to be safe and efficient in humans, the team envisions them being used in conjunction with current vaccines and boosters that work system-wide in order to add immune system reinforcements at the source of infection.
If you care about COVID vaccines, please read studies about vaccines beat natural immunity in fight against COVID-19 and findings of COVID-19 vaccine booster dose can reduce infection in those 60 and older.
For more information about COVID and your health, please see recent studies about the cause of blood clots in severe COVID-19, and results showing that this COVID vaccine is more effective against Delta.
The study is published in Science Immunology. One author of the study is Akiko Iwasaki.
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