A critical review recently published in the Journal of Dental Research examined evidence for various mouth rinses with regard to their potential anti-SARS-CoV-2 activity.¹ The review concluded that mouthwashes with antiviral ingredients could help decrease COVID-19 transmission by reducing viral loads in the mouths of infected patients when they cough, sneeze or speak.²

Only one study was found to investigate the use of mouth rinses containing chlorhexidine against SARS-CoV-2. While chlorhexidine reduced the viral load postgargling for 2 hours, this decrease was transient and the viral load increased again.³

A prospective clinical pilot study found no significant decrease in SARS-CoV-2 intraoral viral load with 1% hydrogen peroxide mouthrinse in COVID-19 patients.⁴

Investigation into SARS-CoV-2 resistance of compounds in garlic essential oil showed that 17 organosulfur compounds had strong interactions with the amino acids of the ACE2 protein and the main protease (PDB6LU7) of SARS-CoV-2, thus predicting its antiviral effects. But this was an in silico study using molecular docking technique.⁵

Evidence for mouthrinses containing povidone-iodine (PVP-I) was also reviewed. In vitro studies have demonstrated that PVP-I also has virucidal activity against SARS-CoV-2.

• Gargle and mouth wash containing PVP-I 1% achieved ≥99.99% virucidal activity against SARS-CoV-2, corresponding to ≥ 4 log₁₀reduction of viral load within 30 seconds of cont⁶
• These results are in accordance with those of a study from Malaysia, which demonstrated 4 log₁₀ reduction in viral load in just 15 seconds with PVP-I gargle and mouthwash against SARS-CoV-2. Application for 30 or 60 seconds reduced the load by >5 log₁₀.⁷
• In an in vitro study, SARS-CoV-2 virus was completely inactivated by PVP-I oral antiseptic rinse at the lowest concentration of 0.5 % and at the lowest contact time of 15 seconds. Hydrogen peroxide at the recommended oral rinse concentrations of 1.5% and 3.0% was minimally effective as a viricidal agent after contact times as long as 30 seconds.⁸
• In a comparative study, thrice-daily gargling with PVP-I for 30 seconds resulted in 100% viral clearance as early as 4 days after the intervention in patients with confirmed Stage 1 Covid-19, which includes asymptomatic persons and first two days of the illness. Viral clearance with essential oils was 80% and with tap water, it was 20%.⁹

According to Dr Florence Carrouel of University Claude Bernard Lyon in France, co-author of the review, everyone should be using these mouthwashes because people can be infected and may not realize it. Three doses of antiviral mouthwash should be used the day before a meeting, and one dose the morning of the event. COVID-19 patients should be using mouthwash regularly for 7-10 days.²

PVP-I has been a widely used antiseptic for many decades. It has the broadest spectrum of antimicrobial action compared with other common antiseptics such as chlorhexidine with activity against Gram‐positive and Gram‐negative bacteria, bacteria spores, fungi, protozoa and several viruses.¹⁰ The multimodal mechanisms of action, rapid onset of action, persistent effect, lack of reported resistance, and an excellent safety profile are other advantages of PVP-I over other commonly available antiseptics.

PVP-I has been demonstrated to have greater antiviral activity against both enveloped and nonenveloped viruses as compared with other antiseptic agents, such as chlorhexidine.¹¹ PVP-I has also demonstrated in vitro activity against SARS-CoV and MERS-CoV.⁶

References

1. F Carrouel, et al. Antiviral activity of reagents in mouth rinses against SARS-CoV-2. J Dent Res. 2020 Oct 22;22034520967933.
2. Antiviral mouthwash could help curb coronavirus transmission - Medscape - Nov 04, 2020.
3. Yoon JG, et al. 2020. Clinical significance of a high SARS-CoV-2 viral load in the saliva. J Korean Med Sci. 35(20):e19.
4. Gottsauner MJ, et al. A prospective clinical pilot study on the effects of a hydrogen peroxide mouthrinse on the intraoral viral load of SARS-CoV-2. Clin Oral Investig. 2020. 24(10):3707–13.
5. Thuy BTP, et al. 2020. Investigation into SARS-CoV-2 resistance of compounds in garlic essential oil. ACS Omega. 5(14):8312–8320
6. Kanagalingam J, et al. Practical use of povidone‐iodine antiseptic in the maintenance of oral health and in the prevention and treatment of common oropharyngeal infections. Int J Clin Pract. 2015;69:1247–56.
7. Kawana R, et al. Inactivation of human viruses by povidone-iodine in comparison with other antiseptics. Dermatology. 1997;195 Suppl 2:29–3.
8. Anderson DE, et al. Povidone-iodine demonstrates rapid in vitro virucidal activity against SARS-CoV-2, the virus causing COVID-19 disease. Infect Dis Ther. 2020:1–7.
9. Hassandarvish P, V Tiong, AB Sazaly, et al. Povidone iodine gargle and mouthwash. Br Dent J. 2020 Jun;228(12):900.
10. Bidra AS, et al. 2020. Comparison of in vitro inactivation of SARS CoV-2 with hydrogen peroxide and povidone-iodine oral antiseptic rinses. J Prosthodont [epub ahead of print 30 Jun 2020]. doi:10.1111/jopr.13220
11. Mohamed NA, et al. Early viral clearance among covid-19 patients when gargling with povidone-iodine and essential oils – a clinical trial. MedRxiv. September 9, 2020.

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA