Can oral rinse mouthwash be another solution to protect you against COVID-19?

‘Never before, scientists say, have so many of the world’s researchers focused so urgently on a single topic. Nearly all other research has ground to a halt.’ The New York Times

Coronavirus disease (COVID-19) is an infectious and air-borne disease caused by a newly discovered coronavirus. The COVID-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or sneezes.

Coronaviruses are surrounded by a fatty layer, called a ‘lipid envelope’ which includes glycoproteins that are required for infection. These glycoproteins are involved in several aspects of the virus’ life cycle, such as assembly, budding, envelope formation, and parthenogenesis. There are agents that are effective at damaging or blocking this lipid envelope – use soap or 60-70% alcohol-based gels to inactivate SARS-CoV-2, as advised by the recent WHO and EPA recommendations. The consensus is that enveloped viruses, such as herpesviruses, orthomyxoviruses, paramyxoviruses and coronaviruses are highly sensitive to 60-70% (v/v) ethanol with almost immediate inactivation.

We are told ‘All you need is a little soap and water’ – but could a complementary approach enhance our protection from Covid-19?

The researchers from Cardiff University’s School of Medicine, along with academics at the universities of Nottingham, Colorado, Ottawa, Barcelona and Cambridge’s Babraham Institute conducted a review to assess if mouthwash had the potential to destroy the outermost layer or ‘envelope’ of the virus, preventing it from replicating in the mouth and throat in the early stages of an infection.

What did this study do?

The researchers reviewed known mechanisms of viral lipid membrane disruption by widely available dental mouthwashes that contain components such as ethanol, chlorhexidine, and hydrogen peroxide. They also assessed existing formulations for potential ability of dental mouthwashes to disrupt the COVID-19 lipid envelope, based on their concentrations of these agents.

The review concluded that research already published on other enveloped viruses, including coronaviruses, directly support the idea that oral rinsing should be considered as a potential way to reduce transmission of COVID-19. In alignment with this, The Independent reports that Professor Valerie O’Donnell, lead author of the study, says that “in test tube experiments and limited clinical studies, some mouthwashes are shown to contain enough of known of ingredients that have capacity to destroy or inactivate viruses through effectively targeting lipids in similar enveloped viruses”. In conclusion, O’Donnell’s team highlight the urgent need for research in this field. They suggest several research methodologies to test this possible complementary protection method: 1. Evaluating existing or specifically-tailored new formulations in well-designed viral lay-friendliness than in clinical trials, 2. Undertaking population-based interventions already available mouthwashes, actively monitoring the outcome to determine efficacy. The evidence from such research is vital to understand whether there is a benefit in double shielded protection from the virus. This is important because we do not know for certain what is the lifecycle, contamination process, and mutation capability of COVID-19. Double shielded protection, if effective, would be of vital importance for high-risk members of the population and health workers who are at high risk of infection.

How well did the media describe the study?

The Independent seemed less sensationalist with their headline by posing a question to the reader. But The Daily Mail’s headline, “Mouthwash could protect against COVID-19…. scientists suggest”, is perhaps slightly misleading, as the conclusion of the study in fact calls for further research before such conclusions could be made.

We need to keep in mind:

• We should continue to follow government health guidance: mouthwash alone is unlikely to protect us from coronavirus – it may be a complementary approach but further research is still needed.
• Oral infection, especially periodontitis/gum disease, are interrelated with a number of systemic diseases such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. This happens through several mechanisms, such as spreading the infection and increasing the host’s susceptibility to disease. Tooth-brushing twice a day is the best protection method against those mechanisms, so we need to keep brushing our teeth at least twice every day.