AN AFFORDABLE way to prevent coronavirus infection may be available in something that is familiar to all who have visited a dental clinic.
It’s the ordinary mouthwash which may be an effective way to slow down the transmission of COVID-19.
We emphasize the word “may” here and do not encourage the use of a mouthwash to prevent COVID-19. As in all medications, a dentist’s or a doctor’s advice is always wise. Otherwise, do not – repeat, do not – self-medicate.
Having said that, we are featuring here a study that is worth mentioning as a piece of information and not – again, not – as a medical advice.
The study was led by Professor Valerie B. O’Donnell of the Systems Immunity Research Institute, School of Medicine, University Hospital of Wales in Cardiff; and Professor David Thomas in the School of Dentistry of the same university hospital.
It was published June 5 in Function, a journal of the American Physiological Society.
The researchers observe that studies increasingly demonstrate the importance of the throat and salivary glands as sites of virus replication and transmission in early COVID-19 disease.
SARS-CoV-2, the virus that causes COVID-19, is an enveloped virus, characterized by an outer lipid membrane derived from the host cell from which it buds. While it is highly sensitive to agents that disrupt lipid biomembranes, there has been no discussion about the potential role of oral rinsing in preventing transmission.
The researchers say there has been no discussion of oral antiviral strategies, apart from a recent response to an article in the British Medical Journal calling for protection for healthcare workers against infection.
The interim guidance of the World Health Organization on the clinical management of SARS-CoV-2 in the home is focused on the use of personal protection, including face masks, along with hand, clothing and surface sanitation, to reduce the risk of airborne and direct spread of the virus. The guidance does not mention oral hygiene, the researchers observe.
Their study is the first to look at known mechanisms of viral lipid membrane disruption by widely available dental mouthwash components that include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide and povidone-iodine.
It also assesses existing formulations for their potential ability to disrupt the SARS-CoV-2 lipid envelope, based on the concentrations of the mouthwash components. It concludes that several deserve clinical evaluation.
The study highlights that already published research on other enveloped viruses, including coronaviruses, “directly supports the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2,” the virus that causes COVID-19.
“This is an under-researched area of major clinical need,” the researchers point out.
They explain: common with many viruses, such as influenza and herpes simplex, coronaviruses are surrounded by a fatty layer, called a “lipid envelope”, into which the spike glycoproteins required for infection are inserted.
“It is widely known that interfering with the lipid envelope represents a virucidal strategy to target many coronaviruses, with a large body of work evidencing the impact of many agents,” Professors O’Donnell and Thomas say.
“We are now widely encouraged to use soap or 60 percent-70 percent alcohol-based gels to inactivate SARS-CoV-2, based on the view that these agents damage the lipid envelope,” they say.
Mouthwashes vary widely in composition. Some commercially available formulations contain ethanol at 14 percent-27 percent in the United Kingdom, Europe and the United States.
The study reviewed the scientific literature to establish whether oral treatment using ethanol-based or other types of mouthwashes could present a strategy to either dampen or reduce viral load, to potentially restrict virus transmission in the current pandemic situation, particularly for vulnerable individuals or healthcare workers.
It found that there is a paucity of data systematically testing the impact of lower (less toxic) ethanol concentrations on enveloped virus inactivation, with most simply reiterating the use of the higher concentrations.
It is becoming increasingly recognized that the throat is a major site of replication and shedding of virus in COVID-19 illness, and that viral load is important, Professors O’Donnell and Thomas say.
Data suggest that the potential for transmission is high early in the disease, they say. While further studies are needed to better understand the relationship between viral load and symptom severity, it is expected that higher levels of viral shedding in the throat or lungs might be associated with an increased ability to infect others.
The route of SARS-CoV-2 infection is currently considered to be via respiratory droplets, similar to SARS-CoV,35 and the virus particle is viable in aerosols for up to three hours.
Assuming that the throat is a major site of replication in the early stages (even before symptoms are apparent), Professors O’Donnell and Thomas observe, “the oral washing using agents that could damage or destroy the lipid envelope has the potential to reduce viral load in the oropharynx.”
Oral agents will impact only on virus that is extracellular or actively budding, they say, adding the persistence of treatment will be important.
How long mouthwash components retain an ability to interact with biomembranes in the mouth is unclear, and more research is required, the study states.
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Dr. Joseph D. Lim is the former Associate Dean of the UE College of Dentistry, former Dean of the College of Dentistry, National University, past president and honorary fellow of the Asian Oral Implant Academy, and honorary fellow of the Japan College of Oral Implantologists. Honorary Life Member of Thai Association of Dental Implantology. For questions on dental health, e-mail or text 0917-8591515./PN
