This article on mucosal immunity provides helpful context for intranasal vaccines:<p>> Many microbes, including the coronavirus, enter the body through the mucosa — wet, squishy tissues that line the nose, mouth, lungs and digestive tract — triggering a unique immune response from cells and molecules there. Intramuscular vaccines generally do a poor job of eliciting this mucosal response, and must instead rely on immune cells mobilized from elsewhere in the body flocking to the site of infection.<p>> Given the potency and rapid spread of the coronavirus, some say it makes sense to develop vaccines for the airway as well as the more standard jabs. “Knowing how potent mucosal responses can be against a viral pathogen, it would be ideal to be thinking about mucosal vaccines,” said Akiko Iwasaki, an immunologist at Yale University.<p><a href="https://www.nytimes.com/2020/07/14/health/coronavirus-nasal-vaccines.html" rel="nofollow">https://www.nytimes.com/2020/07/14/health/coronavirus-nasal-...</a><p>And here’s one of the first studies using a mouse model (AFAIK) for SARS-CoV-2 if you want to see how that works: <a href="https://rupress.org/jem/article/217/12/e20201241/151999/Mouse-model-of-SARS-CoV-2-reveals-inflammatory" rel="nofollow">https://rupress.org/jem/article/217/12/e20201241/151999/Mous...</a>