Nasal vaccines are inhaled the same as a respiratory virus is inhaled. The theory is they'll trigger immunity in the same tissues the virus would first encount

Nasal vaccines are inhaled the same as a respiratory virus is inhaled. The theory is they'll trigger immunity in the same tissues the virus would first encounter, instead of letting the virus get a foothold in the respiratory system before reaching the rest of your body, where an injected vaccine would have built the most immunity.