A snort or a jab? Scientists debate potential benefits of intranasal Covid-19 vaccines

As the world amasses experience with Covid-19 vaccines, something we should have known from the start is coming into sharp focus.

Vaccines that are injected into arm muscles aren’t likely to be able to protect our nasal passages from marauding SARS-CoV-2 viruses for very long, even if they are doing a terrific job protecting lungs from the virus. If we want vaccines that protect our upper respiratory tracts, we may need products that are administered in the nose — intranasal vaccines.