The nasal lining serves an important role in the innate immune system, providing a primary defense against inhaled viruses, bacteria, and other particulates. This lining, consisting of a superficial mucus layer atop an aqueous base, traps inhaled particulates that are then propelled by underlying cilia into the nasopharynx. Topical rinses take advantage of this secretory lining in multiple ways.

1. Nasal rinses physically disrupt the viscous surface layer, removing the mucus and its associated particulate matter
2. The presence of nasal saline helps to increase hydration of the deeper aqueous layer, improving the underlying ciliary beat frequency and reducing local inflammatory mediators

While the benefit of topical nasal saline has been well established, optimal saline tonicity has been debated. While there is evidence to support topical therapies for viral transmission mitigation, the potential risks must also be considered. SARS-CoV-2 is likely transmitted via physical contact with the virus through direct or indirect transfer to the upper aerodigestive tract mucosa or exposure to infected respiratory droplets. There is concern that performing irrigations of the nasal cavities may increase viral shedding and transmission.

However, SARS-CoV-2 is a highly virulent respiratory virus with a significant presence in the nasal and nasopharyngeal mucosa. Hypertonic nasal saline, which facilitates mucociliary clearance, likely decreases viral burden through physical removal. If you are currently using nasal saline washes, don’t stop; it may actually slow the spread of COVID-19!

Stay the course, stay well, mask up, and stay tuned!