What do we know about COVID-19 nasal vaccines so far
Up until now, coronavirus vaccines have offered sufficient protection against the SARs-COV-2 virus. While breakthrough infections have been on the rise, existing vaccines have in fact lowered the number of severe illnesses and minimized the risk of hospitalization and death.
However, with the emergence of new variants, scientists have been in a scurry to evaluate the efficacy of available vaccines and the booster shots. Additionally, vaccine-manufacturing companies have been looking into new prospects to heighten vaccine efficacy.
Nasal vaccines, for one, are now considered to be the most recent shot of hope in our fight against the new COVID variant Omicron. Hyderabad-based Bharat Biotech, who are the makers of Covaxin, are currently working towards developing an intranasal vaccine shot, which could strengthen the body's immune response against the virus.
Difference between nasal and intramuscular COVID vaccines
Injected or intramuscular vaccines are injected into the skin with the help of injections (needles). Whereas unlike traditional vaccines, nasal vaccines target the virus present in the mucosal membranes and are given via the nose, rather than orally or through the arm.
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While injected vaccine shots produce circulating Immunoglobulin G (IgG) antibodies that fight off deadly pathogens even before they can cause severe tissue damage, but are not exactly effective in managing viral entry into the body.
That said, nasal vaccines are easier to administer and may provide easy immunity. An effective nasal jab could protect against COVID-19 and its variants by directly interacting with T-cells that exist in the nose and the throat and target the immune cells present in the mucosal membrane.
How do nasal vaccines work?
Since most viruses, including the ones associated with SARs-COV-2, enter the body through the mucosa and infect the cells and molecules present in the mucosal membranes, nasal vaccines are seen as an effective solution for the same.
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Given that intranasal vaccines produce secretory Immunoglobulin A (IgA), it manages to evoke a strong immune response at the site of virus entry i.e. the nose. IgA is said to be more efficacious in managing and destroying viruses at an early stage of infection than IgG. This may somehow not only fight off infections, but may also avoid transmission. While nasal vaccines generate a robust and effective mucosal immune response, it avoids further damage to the lungs.
Amid Omicron outbreak, can nasal sprays provide protection?
Studies have shown that nasal vaccines have proved effective against respiratory viruses. It is now believed that it can wade off the Omicron variant too.
A recent study published in the journal Science Immunology, found that nasal vaccines fought against respiratory viruses in mice, while systemic immunisation or injected vaccines, did not.
Additionally, researchers found that the nasal vaccines created antibodies that protected the animals against a variety of flu strains, not just the targeted strain.
Akiko Iwasaki, Professor of Immunobiology at Yale University believes that the best immune defence takes place at the gate, "guarding against viruses trying to enter". Since nasal vaccines are said to evoke a strong immune response at the site of virus entry i.e. the nose, it is believed to be effective against COVID-19 and possibly the new variants.
How can you ensure safety from the new variant?
Apart from getting COVID vaccines, following COVID-appropriate behaviour is the need of the hour.
Wear your masks regularly, especially when you're off to somewhere crowded. Maintain social distancing, avoid public places, practice proper hand hygiene and do not let your guard down yet. Although the number of COVID cases have not been as high as during the second wave, there is no telling when a third wave could take us all by surprise.