Nose Spray Vaccines Could Quash COVID Virus Variants

The relentless evolution of the COVID-causing coronavirus has taken a bit of the shine off the vaccines developed during the first year of the pandemic. Versions of the virus that now dominate circulationOmicron and its subvariants—are more transmissible and adept at evading the body’s immune defenses than its original form. The current shots to the arm can still prevent serious illness, but their ability to ward off infection completely has been diminished. And part of the reason may be the location of the jabs, which some scientists now want to change.

To block infections entirely, scientists want to deliver inoculations to the site where the virus first makes contact: the nose. People could simply spray the vaccines up their nostrils at home, making the preparation much easier to administer. There are eight of these nasal vaccines in clinical development now and three in phase 3 clinical trials, where they are being tested in large groups of people. But making these vaccines has proven to be slow going because of the challenges of creating formulations for this unfamiliar route that are both safe and effective.

What could be most important about nasal vaccines is their ability to awaken a powerful bodily defender known as mucosal immunity, something largely untapped by the standard shots. The mucosal system relies on specialized cells and antibodies within the mucus-rich lining of the nose and other parts of our airways, as well as the gut. These elements move fast and arrive first, stopping the virus, SARS-CoV-2, before it can create a deep infection. “We are dealing with a different threat than we were in 2020,” says Akiko Iwasaki, an immunologist at Yale University. “If we want to contain the spread of the virus, the only way to do that is through mucosal immunity.

Iwasaki is leading one of several research groups in the U.S. and elsewhere that are working on nasal vaccines. Some of the sprays encapsulate the coronavirusspike proteins—the prominent molecule that the virus uses to bind to human cells—into tiny droplets that can be puffed into the sinuses. Others add the gene for the spike to harmless versions of common viruses, such as adenoviruses, and use the defanged virus to deliver the gene into nasal tissue. Still others rely on synthetically bioengineered SARS-CoV-2 converted into a weakened form known as a live attenuated vaccine.

Sourc: https://www.scientificamerican.com/