scientists believe a vaccine that doctors spray into the patient's nose would work better than a vaccine injected into the patient's veins. after a nasal vaccine, the body's immune cells look for the virus in the nose and mouth. the nose and mouth are where most people are infected with sars-cov-2. scientists are not sure why this works. as of july 2020, teams in the netherlands, the united states, and canada are making nasal vaccines.