Rajeev Chitguppi MDS Profile picture
Apr 29, 2020 9 tweets 5 min read Read on X
Thread:
Effect of Chlorhexidine CHX on coronavirus:

CHX concentration tested in various studies till now has been too low.
1st study: CHX 0.02% w/v (1988)
2nd study: 0.01125- 0.015 % w/v (1998)
These conc. are too low & these studies didn't test CHX against coronavirus either
When Hong Kong University researchers increased the Chlorhexidine concentration by just three units i.e. from 0.02% to 0.05% CHX was found to be effective against the coronavirus. CHX was found to be as effective as 7.5% Povidone Iodine or 70% ethyl alcohol.
Hence dental & medical practitioners need not worry about Chlorhexidine gluconate being ineffective against the novel Coronavirus. The concentrations used in the earlier experiments are too low, and worse, they were not even tested against the novel coronavirus.
The CHX conc. tested in early experiments (< 0.02%) was so low that currently no CHX products are available in such low conc.

CHX mouthwashes available in the market (0.12% & 0.2%) now are 2- 4 times more conc. than the CHX conc. that inactivates the novel coronavirus (0.05%).
Chlorhexidine alcohol based hand rubs (0.5% w/v) are TEN times more concentrated than what is needed (0.05%) to inactivate the novel coronavirus.

Chlorhexidine hand scrubs (4% w/v) are EIGHTY times more concentrated than what is needed to inactivate the novel coronavirus.
It means Chlorhexidine is very much effective against novel coronavirus. Hong Kong University study published in The Lancet Microbe says "0.05% CHX works as good as 7.5% Povidone Iodine or 70% Ethyl Alcohol"

So where is the question of CHX being ineffective against coronavirus?
All concerned #Dentistry #Periodontics authorities @AmerDentalAssn @AmerAcadPerio @PerioEurope @fdiworlddental @WHO @CDCgov @CDC_NCEZID @USPharmacopeia @The_BDJ should come up with a statement on the efficacy & effectiveness of Chlorhexidine against novel coronavirus #SARS_COV_2
There has been some serious misinterpretation of study results. With the latest study by @hkumed showing that Chlorhexidine is as effective as Povidone Iodine & Ethyl alcohol [even in very low (0.05%) conc.] there is an urgent need to inform dentists & medical practitioners.
To read my analysis of all studies published till now on the topic "Effect of Chlorhexidine on Coronavirus" please download my article from Researchgate. Points to the exact reason why there is a misconception & what should be the correct interpretation
researchgate.net/publication/34…

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More from @chitguppi

Jan 8, 2022
1/ Who gets severe COVID-19?

COVID-19 is a double-defect disease:

1. A defective early control of the virus by type I / III Interferons (IFN)

2. An impaired ability to control proinflammatory activities.

Only when both these checkpoints fail will critical disease develop.
2/ Interferons (IFN)

SARS-CoV-2 is a poor inducer of IFN:

Triggers limited & delayed type I / III IFN responses.

On the other hand, the virus is highly sensitive to IFN treatment similar to other coronaviruses.
3/ Despite modest IFN induction, this innate antiviral response is critical for infection control. #COVID19

@SciImmunology 7 Jan 2022

science.org/doi/10.1126/sc…
Read 6 tweets
Jan 8, 2022
Neutralizing antibodies are a good indicator of protection,
- not only against severe disease
- but also (if amounts are very high) against viral replication in the mucosa (with or without symptoms), thereby reducing transmission. #COVID19

However... 1/n science.org/doi/10.1126/sc…
However, this does not mean that it is circulating antibody that is causing protection:

- Antibody in the serum does not normally diffuse (or get transported) into mucosal fluids.

- Also... (2/n)
science.org/doi/10.1126/sc…
Also, protection against superficial infection depends on

- mucosal antibodies [including immunoglobulin A (IgA)],

and possibly on

- antiviral T cells that reside within the linings of the respiratory tract. (3/n)
science.org/doi/10.1126/sc…
Read 5 tweets
Jan 4, 2022
1/ Which oral/ periodontal pathogen acts similar to viruses when it comes to suppressing host immunity?

Background:

Anatomical (mucosal/ epithelial) barriers confer antiviral immunity via interferon (IFN) production.

IFNs function like antiviral cytokines...
2/ IFNs function as antiviral cytokines and restrict viral infection, replication, and release.

Oral epithelial cells fight viral infections by inducing Type III IFNs (IFN-λ) preferentially.

Latest evidence:

Recent study PNAS, 21 Dec 2021
3/ A recent study showed that IFN production and antiviral immunity are severely compromised by one oral bacterial pathogen.

And that is Porphyromonas gingivalis (Pg).

Molecular pathways employed by Pg are strikingly parallel to those utilized by viruses for IFN suppression.
Read 4 tweets
Jan 4, 2022
1/ Delta variant was highly pathogenic due to its ability to cause cell-cell fusion & syncytia formation.

But this pathogenicity came with Terms & Conditions.

"S1/2 cleavage should be optimal for cells expressing TMPRSS2 (lower airway)"

Omicron #COVID19 story is different.
2/ Cell-cell fusion mediated by spike glycoprotein requires S1/S2 cleavage, but is also dependent on TMPRSS2 presence.

Omicron spike is relatively poorly cleaved.

Way suboptimal compared to Delta

Due to this suboptimal cleavage lower airway infection is less with Omicron.
3/ So, Omicron shows impaired entry & replication in lung cells that express TMPRSS2 (a serine protease enriched in lung alveolar type 1 & 2 cells).

This reduced cleavage is also associated with poorer cell-cell fusion and syncytia formation.

This tells us about upper airway
Read 5 tweets
Jan 3, 2022
1/ Omicron's 3 mutations (P681H, H655Y, N679K) in furin cleavage site region were initially predicted to favor its pathogenicity: cell-cell fusion & syncytia formation.

But reality is different.

Omicron's cleavage efficiency is substantially lower than Delta variant. #COVID19
2/ Omicron spike is relatively poorly cleaved.

It shows impaired entry & replication in lung cells that express TMPRSS2, a serine protease enriched in lung alveolar type 1 & 2 cells.

This reduced cleavage is also associated with poorer cell-cell fusion and syncytia formation.
3/ Cell-cell fusion mediated by spike glycoprotein requires S1/S2 cleavage, but is also dependent on TMPRSS2 presence.

Fusogenicity of Omicron spike was severely impaired despite TMPRSS2 expression, leading to marked reduction in syncytium formation compared to Delta spike.
Read 4 tweets
Jan 3, 2022
Omicron infects throat more & lungs less compared to earlier variants.

Simple strategy: As soon as you get sore throat start with Chlorhexidine (CHX) mouthwash for throat gargling

Study: 4 day CHX use eliminated #SARSCOV2 virus from oropharynx. #COVID19
All studies done on Chlorhexidine and its antiviral actions esp. against SARS-COV-2 summarized in my blog

"Chlorhexidine gluconate — the most effective antiviral mouthwash in COVID-19 pandemic"

chitguppi.medium.com/chlorhexidine-…
My earlier thread on Chlorhexidine mouthwash and its antiviral effects against SARS-COV-2

Read 5 tweets

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