Efficacy of commercial mouth‑rinses on SARS‑CoV‑2 viral load in saliva: randomized control trial in Singapore

by Imaan Amien

Can mouthwash stop the spread of COVID?

Introduction

They say that a warm smile is the universal language of kindness.  Thankfully there are dentists, oral hygienists and prosthodontists that can help us to improve our smiles, however according to the World Economic Forum analysis, these professions are listed amongst occupations that carry the highest risk of contracting COVID-19 (1). 

As of June 2021, over 181 million people have contracted the SARS-CoV-2 virus, and nearly 4 million people have lost their lives as a result.  South Africa is still very much behind on vaccine rollout compared to developed nations; therefore we rely on public health measures such as hand hygiene, mask wearing and social distancing to mitigate the spread.  Studies have shown that the SARS-CoV-2 virus is present in the saliva of 91.7% of COVID-19 patients, therefore people can contract the virus directly through aerosol droplets or indirectly by coming into contact with contaminated surfaces.  Therefore reducing salivary viral titers could be a key approach in preventing transmission. 

It has been suggested that anti-septic mouth-rinsing could be performed as a pre-procedural infection control measure when people undergo dental procedures to inhibit aerosol spread via saliva, however as of yet no clinical trials have been performed to measure the efficacy of mouth rinses to reduce SARS-CoV-2 salivary viral titers.  Therefore the researchers aimed to investigate the efficacy of three commercially-available mouth rinses containing either Cetylpyridinium chloride (CPC), povidone–iodine (PI) or chlorohexidine (CHX) on salivary SARS-CoV-2 viral load in COVID-19 positive patients. 

Methods

To do so a randomized clinical study was performed whereby researchers randomly separated patients into four groups to receive the three different mouthwashes and one group with water as a control.  Their saliva was collected & PCR was done to assess salivary viral load. 

Results & discussion

The results showed that CPC & PI mouth-rinses have a sustained effect in reducing the viral load compared to the control group.  This is due to the fact that both CPC & PI disrupt the lipid membrane of SARS-CoV-2 and therefore interfere with the ability of the spike protein to bind to the ACE2 receptor of oral mucosal cells. CHX-based mouthwash did not show a significant reduction in viral load (Figure 1). 

Conclusion

The data therefore proves that commercially available mouth-rinses that contain CPC (Colgate Plax) or PI (Betadine) can be used to effectively reduce salivary viral load.  This is useful not only for dental procedures, but also as an effective public health strategy, as it may help to minimize SARS-CoV-2 transmission in asymptomatic individuals via the oral route.  

Reference

1.         Seneviratne CJ, Balan P, Ko KKK, Udawatte NS, Lai D, Ng DHL, et al. Efficacy of commercial mouth-rinses on SARS-CoV-2 viral load in saliva: randomized control trial in Singapore. Infection. 2021;49(2):305-11.

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