Could mouthwash help protect against COVID-19?

If you want to reduce the possibility of spreading COVID-19, it could pay to spend extra attention on oral hygiene, according to a new study.

A German research team has shown that Sars-Cov-2 viruses can be inactivated using certain commercially available mouthwashes. 

This follows on from findings from researchers at Cardiff University, who led a study to assess the importance of the throat and saliva glands in the replication of Covid-19. They stated that their research showed that mouthwash has 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”.

The virus strain that causes COVID-19, is protected by a fatty (lipid) membrane.

This lipid may help a virus survive and infect other cells. 

At the time, lead author Valerie O’Donnell commented on the Cardiff findings: “We found that there is evidence from other people’s research that enveloped viruses like influenza, herpes simplex, and other coronaviruses are sensitive to common ingredients in mouthwash, but this evidence is from test-tube experiments — not from studies on viruses in the mouth, where their response may be different, and where little work has been done.”

High viral load in the mouth

We already know that there are high viral loads in the mouths and and throats of some COVID-19 patients – this is one of the reasons for the governments U-turn on the wearing of masks.

But the latest German research indicates that regular use of mouthwash may be another way to reduce the viral load.

Virologists from Ruhr-Universität Bochum along with colleagues from Jena, Ulm, Duisburg-Essen, Nuremberg and Bremen used cell culture experiments to see whether mouthwash could be effective in lowering the risk of transmission.

The researchers tested eight mouthwashes with different ingredients that are available in pharmacies or drugstores in Germany. They mixed each mouthwash with virus particles and a chemical to recreate the effect of saliva in the mouth. The mixture was then shaken for 30 seconds to simulate the effect of gargling. 

They then assessed the results. All of the tested preparations reduced the initial virus, supporting the finding from Cardiff University. 

Three mouthwashes reduced it to such an extent that no virus could be detected after an exposure time of 30 seconds. 

One of the authors Toni Meister comments: "Gargling with a mouthwash cannot inhibit the production of viruses in the cells, but could reduce the viral load in the short term where the greatest potential for infection comes from, namely in the oral cavity and throat -- and this could be useful in certain situations, such as at the dentist or during the medical care of COVID-19 patients."

The Bochum group is now looking at the possibilities of a clinical study on the efficacy of mouthwashes on Sars-Cov-2 viruses, during which the scientists want to test whether the effect can also be detected in patients and how long it lasts. 

It is important to state that this research is preliminary. For now, the best advice in how to avoid catching COVID-19 or spreading it to others, is social distancing.

Social distancing tips

  • Stay at least 2 metres (3 steps) away from anyone you do not live with
  • Wash your hands with soap and water often
  • Use hand sanitiser if this is not possible
  • Taking early self-isolation and quarantine
  • Use a tissue for coughs and sneezes
  • seek remote medical advice and
  • Avoid large gatherings or crowded places

This latest research, Virucidal efficacy of different oral rinses against SARS-CoV-2, is published in The Journal of Infectious Diseases.

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