Handwashing has always been our primary way of warding off a wide range of disease-causing viruses and bacteria.  With our hands being always at risk of making contact with surfaces covered with these germs, it goes without saying that the simple act of washing our hands with soap and water will stop these viruses and bacteria from being carried into our body’s gateways like the mouth, nose and eyes.

However, some viruses can bypass this layer of protection by being carried directly into the nose by droplets in the air released by coughing, sneezing or even talking which causes respiratory tract infections like the common colds, flu, or even the currently dreaded coronavirus of COVID-19 also known as SARS-CoV-2.

In an effort to protect healthcare workers from COVID-19, the China Dermatologist Association, Chinese Society of Dermatology and National Clinical Research Center for Skin and Immune Diseases jointly published in March 2020 a consensus for protecting the skin, eyes, as well as the linings of the nose and mouth.  Among the recommendations is to regularly clean the inside of the nose with normal salt solution especially after visiting isolation wards with COVID-19 patients.¹

The nose is recognized to be particularly vulnerable to SARS-CoV-2.  It was found that angiotensin converting enzyme‐2 (ACE2), the exact bodily enzyme which coronaviruses use to enter and infect cells are found on the tissues of the nasal lining.²

This finding is further strengthened in a more recent study published in Nature in May 2020, wherein a group of international researchers led by Dr. Waradon Sungnak of Wellcome Sanger Institute, UK, found that the level of this ACE2 which allows infection of SARS-CoV-2 are actually highest among nasal cells compared with the rest of the body.³

Rinsing the nasal cavities to dislodge these germs before they get the chance of attaching to the cells and causing an infection then becomes a logical consideration. 

Use of salt-based wash or saline, particularly with sodium chloride or potassium chloride, appears appropriate for the purpose of nasal rinsing to protect against viral infection.  In 2018, Virologist Dr. Sandeep Ramalingam and other researchers from the University of Edinburgh, UK, showed in their study that cells are able to absorb chloride and turn it into a form of bleach to neutralize viruses.⁴ 

Numerous studies support the use of nasal washing in managing various nasal conditions, including those caused by viral infections.  In one particular study in 2008 by Dr. Ivo Slapak, pediatric otorhinolaryngologist, and a group of researchers in the Czech Republic, the effectivity of using saline wash for the nose to prevent reappearance of cold and flu was explored. In their study, 401 children aged 6-10 affected with cold or flu were divided into groups with one group receiving a nasal wash while the other had standard treatment.  Aside from showing faster resolution of symptoms among those who did nasal washing, it was found that these children on nasal washing had fewer sick days (31% under nasal washing vs. 75% under standard treatment) and school absences (17% under nasal washing vs. 35% under standard treatment).⁵

Vaccines and anti-viral agents remain to be the definitive measures against viral respiratory infections.  However, for some conditions like COVID-19, these are still unavailable.  Together with regular handwashing, physical distancing, a healthy diet and exercise, regular nasal washing with the appropriate salt solution may be considered as a safe, economical and accessible means to confer additional protection from respiratory infections.  Nasal washing devices prepared under stringent standards like nasal sprays and large-volume irrigating kits are already readily available.  Nasal sprays which deliver a fine mist of saline solution into the nose are designed to be handy and on-the-go.  Meanwhile, large-volume irrigating kits are intended for a more thorough cleansing of the nose and sinuses.  Indeed, more studies are under way to fully establish their role in preventing these viral infections.  To find out more on how to be effectively and safely protected from viral respiratory conditions, it still is best to have a talk with your personal doctor.

References:

Yan Y, Chen H, Chen L, et al. Consensus of Chinese experts on protection of skin and mucous membrane barrier for health-care workers fighting against coronavirus disease 2019.

Sungnak W, Huang N, Bécavin C, et al. SARS-CoV-2 entry factors are highly expressed in nasal epithelial cells together with innate immune genes. Nat Med.

Ramalingam S, Cai B, Wong J, et al. Antiviral innate immune response in non-myeloid cells is augmented by chloride ions via an increase in intracellular hypochlorous acid levels. Sci Rep.

Slapak I, Skoupá J, Strnad P, Horník P. Efficacy of isotonic nasal wash (seawater) in the treatment and prevention of rhinitis in children. Arch Otolaryngol Head Neck Surg.