Chlorhexidine mouthwash to prevent Covid-19 spread inside clinics & protect healthcare workers

Photo by Ashkan Forouzani on Unsplash

Covid-19 spreads mainly by droplets that come out of the mouth and nose via coughing, sneezing, talking etc. SARS-CoV-2 is a highly infectious virus about which a lot still remains to be studied. It’s critical that we prevent the spread of the virus — inside the buildings (residences, offices, clinics, hospitals etc.) and also in community settings. Global data has shown that healthcare workers are getting infected and losing lives, in spite of following standard disinfection and prevention protocols in their practice. Therefore, it’s very critical that we develop additional layers of prevention to protect them from the spread of infection inside the clinics. Reducing the viral loads in patients’ saliva could be one area that deserves high attention.

Mouth rinses to reduce viral loads in the mouth:

SARS-COV-2 is a weak virus. You destroy the envelope and it gets inactivated. There is no challenge in killing the virus. A lot of chemicals inactivate it. However, the antiviral mechanism is different outside the mouth, and the challenges are different inside the mouth.

1. The question is not about inactivating only the existing virus, and that too, just one time, but about for how long any new virus that enters the oral cavity will be neutralized again & again. It’s about how long the viral loads will be kept low.
2. Any agent may inactivate the virus outside the mouth. But the most critical question is how well it will act & how long the action will last “inside the mouth”.
3. How long a healthcare worker can feel safe due to persistently reduced viral loads in the mouth during which he can complete the appointment and a short procedure.

In short, combining all three points, we can define the problem as- “which mouthwash can reduce the viral loads inside the mouth & keep them low for sufficiently long so that the chances of virus spread inside the clinics are reduced and the healthcare workers are effectively protected from getting infected?”

Argument: Substantivity is the most critical property of a mouthwash.

We are not giving a mouthwash to kill only the existing viruses in the mouth. We want to neutralize the new viruses that may enter the saliva in the next 30 to 60 minutes. We want to ensure that in the next half an hour or one hour of appointment on dental chair whatever new virus that enters the saliva (patient’s mouth) from the respiratory tract or salivary glands should be neutralized. This is not to cure the patient but to save ourselves from the spread.

Mouthwashes like Povidone-Iodine and H2O2 will kill the virus once you rinse, but their action gets over as soon as you spit them out. And within the next few minutes again the saliva gets flooded with new viruses getting shed from salivary glands and respiratory system. But now, Povidone-Iodine or H2O2 would not be there in the mouth to counter the new virus.

Hence, we need mouthwashes that, through their persistent attachment and sustained release into saliva, not only reduce the viral loads in saliva but also maintain low viral loads for a sufficient amount of time. It’s during this safe period of low viral loads when the chances of droplet spread are reduced that the doctors can complete their appointment: check-up and a short clinical procedure.

This property of strong & persistent attachment to oral tissues and sustained release into saliva is known as Substantivity. Only Chlorhexidine has substantivity. Other mouthwashes like Povidone Iodine & Hydrogen Peroxide show no substantivity.

What is the evidence for Substantivity?

Classification of currently available mouthwashes based on their property of substantivity: (BDJ, 1999) This evidence is known for decades. Click here to read

1. Class A: Rich with substantivity: Chlorhexidine, which continues to act even after you spit it out after rinsing, thanks to strong attachment and sustained release.

Read the latest report on Chlorhexidine substantivity in my other article

1. Class B & C: No substantivity: Povidone-Iodine/ Hydrogen peroxide/ essential oils / hypochlorous acid etc. They act only as long as you are rinsing. you spit them out and their action is over.

Chlorhexidine against viruses including the novel coronavirus

1. It is known since 1990 that Chlorhexidine acts against the envelope of enveloped viruses like the novel coronavirus. Click here to read the article.
2. In the initial phase (Feb March 2020) of the current pandemic, there was a misconception that Chlorhexidine may not be effective against the novel coronavirus, most of which was due to misinterpretation of evidence. Lancet article from Hong Kong University in April 2020 put all doubts and misconceptions to rest. Lancet article showed that Chlorhexidine can inactivate the novel coronavirus in concentrations as low as 0.05%. Currently available Chlorhexidine formulations are much stronger than 0.05% so they will easily inactivate the virus. Here is the link to my article that has a detailed analysis of all the evidence and the reasons that gave rise to the misconception. Click here to read my article on Researchgate
3. Chlorhexidine is the only mouthwash to have the property of substantivity that needs to be utilized in the prevention of Covid-19 spread. This is the link to my article “Mouth rinses with substantivity can prevent COVID-19 spread and protect the healthcare workers”.

How to use Chlorhexidine mouthwash?

1. Follow the 10–20–30 rule. Take 10 ml of 0.20% w/v concentrated Chlorhexidine mouthwash and rinse for 30 seconds at least.
2. Use it undiluted preferably. But if you find it irritating, add a minimum amount of water and take the whole mix in one go.

Summary:

What works outside the mouth may not work inside the mouth, and what works inside the mouth may not have a persistent action. The key principle is persistent action inside the mouth. In short, SUBSTANTIVITY.

To work inside the mouth and to keep the viral loads persistently low, a chemical needs to have a persistent attachment to oral tissues and a persistent release into saliva. Povidone-Iodine and H2O2 have no persistent attachment or no persistent release. You spit them out and their action is over. In other words ZERO substantivity. This is a piece of evidence known for decades.

That’s why go for mouthwashes with substantivity eg. Chlorhexidine

Conclusion:

Long antiviral action inside the mouth is required for preventing #covid19 spread by droplets and this is possible only with those mouthwashes that have strong intraoral attachment mechanisms and sustained release into saliva. This property of mouthwashes is called Substantivity.

Among the currently available mouthwashes, only Chlorhexidine displays the property of substantivity. Other agents like Povidone-Iodine and Hydrogen Peroxide do not have substantivity and hence may not offer any protection from the spread of Covid-19.

Practical implications:

It’s time to add Chlorhexidine mouth rinse to the existing COVID-19 prevention protocols. Chlorhexidine will not remove or substitute any of the existing standard protocols but only add and reinforce them. Hence, before you step out of your home

1. Use Chlorhexidine mouthwash. 10 ml of 0.20% w/v CHX rinsed for 30 sec (10- 20- 30 rule)

2. Wear the right mask, the right way

3. Wear a well-fitting eye-wear

4. Maintain physical distancing

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The entire story of the antiviral action of chlorhexidine and its practical implications explained in one image