New preclinical research at Yale University suggests intranasal vaccines (delivered through the nose) may generate stronger immunity against air-borne viruses compared to more conventional injection-delivered vaccines. Not only is an inhalable nasal spray a much easier vaccine delivery system to administer but may even promote immunity against more than just the single viral strain in a vaccine.

In comparing the delivery of an influenza vaccine nasally and through injection in a series of mouse experiments, researchers led by Yale professor of Immunobiology, Akiko Iwasaki, report a surprising find: mice receiving the nasal vaccine were much better protected from a broad variety of influenza strains compared to the mice receiving injections.

The researchers later discovered that the nasal vaccine directly induced significant immunoglobulin A (IgA) secretion in nasal mucous membranes and in the lings.

[IgA antibodies are one of the immune system’s frontline soldiers. These antibodies are primarily secreted by mucosal surfaces in the body, mostly seen in the nose, gut and lungs.]

“When you look inside the lungs of nasal vs. parenteral primed mice 5 weeks later, nasal primed mice contain tons of plasma cells secreting IgA beneath the epithelium, and IgA is bathing the lumen of the lung,” Iwasaki explained on Twitter. “These IgA secreting cells at 5 weeks post prime are mostly tissue-resident cells (cells that sit within the lung and do not move around).”

“These results indicate that nasal vaccines induce IgA and promote better cross-protective immunity against viral variants, and suggest its utility in combating [emerging] COVID-19 variants of concern,” Iwasaki pointed out.

A number of inhalable nasal COVID-19 vaccines are in development, with several already in early human trial stages – the Yale researchers conducting similar tests in animals with COVID-19 vaccines as well.

Read: Moderna plans to develop a single vaccine against multiple respiratory viruses