Vaccine is administered into a nose. A pharmaceutically-acceptable aqueous saline solution carrier comprising from 0.5% to 1.9% salt is provided in a nasal device. The saline solution is administered into a first nasal cavity to rinse the first nasal cavity. The saline solution is added to the first nasal cavity until the saline solution flows via a posterior nasal aperture into a second nasal cavity. A vaccine is then administered into the first nasal cavity.