Efficacy of sanitizers against SARS-CoV-2 based on alcohol content

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Discussion Overview

The discussion centers on the efficacy of hand sanitizers against SARS-CoV-2, specifically focusing on the alcohol content in these sanitizers, including ethanol and isopropanol (IPA). Participants explore the recommended alcohol concentrations by WHO and question the effectiveness of lower alcohol percentages in sanitizers available to the public.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that WHO recommends 80% (v/v) ethanol and 75% (v/v) IPA for effective sanitization, while others mention that commonly available sanitizers often contain lower concentrations, such as 70% ethanol.
  • One participant expresses concern about the use of denatured alcohol in sanitizers, questioning its safety and effectiveness, given that denatured alcohol is often mixed with toxic substances.
  • Another participant clarifies that "denatured alcohol" typically refers to ethanol that has been chemically altered to prevent consumption, but the specific additives can vary by region.
  • References to studies and guidelines are provided, suggesting that even lower concentrations, such as 60% alcohol, may still be effective against SARS-CoV-2, although the credibility of these claims is questioned.
  • One participant cites WHO guidelines indicating that the microbicidal activity of recommended formulations was tested and found effective, comparing it to isopropanol at 60% concentration.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of sanitizers with lower alcohol content, and there is no consensus on the safety of denatured alcohol in sanitizers. The discussion remains unresolved regarding the efficacy of various alcohol concentrations against SARS-CoV-2.

Contextual Notes

Limitations include a lack of consensus on the safety and effectiveness of different alcohol concentrations in sanitizers, as well as the variability in definitions and formulations of denatured alcohol across regions.

Wrichik Basu
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Ethanol and 2-propanol (hereafter abbreviated "IPA") are the two alcohols that are used in hand-sanitizers. As per the standards set by WHO, the recommended levels are 80% (v/v) of ethanol and 75% (v/v) for IPA, along with other components like glycerol and hydrogen peroxide. Refer to the https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf for details (a pdf file). A snapshot:

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None of the handrubs I have seen has the above composition. The ones that are preferred by hospitals have 70% (v/v) ethanol and 2.5% (v/v) chlorhexidine gluconate IP; these are not generally available in pharmacies for the common people.

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Sanitizers produced by another famed brand has 72.43% (v/v) alcohol IP (denatured). My knowledge in chemistry is quite limited, but I thought denatured alcohol is poisonous; no idea how they are putting it in a sanitizer.

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Question: Are these sanitizers with a lower percentage of alcohol effective against the SARS-CoV-2?

One website says that even 60% (v/v) of either of the two alcohols will work, but it did not site any sources and hence lacks credibility.
 
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Wrichik Basu said:
Sanitizers produced by another famed brand has 72.43% (v/v) alcohol IP (denatured). My knowledge in chemistry is quite limited, but I thought denatured alcohol is poisonous; no idea how they are putting it in a sanitizer.
"Denatured alcohol" does not -as far as I know- have a "chemical" definition. Typically, it just means ethanol (the stuff you can drink) which has had some other chemicals added to it to discourage people from drinking it. What is is added depends on where you are in the world, but typically it will be something like methanol (which is indeed somewhat toxic if you get it on your skin) plus perhaps some other chemicals to induce vomiting and a dye.
In this context I doubt they use methanol, denatured here probably just means that somewhere in the production line something has been added to make the hand sanitiser harder to drink (which btw is something people do)
 
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From the same WHO guidelines (a little further down):
The microbicidal activity of the two WHO-recommended formulations was tested by WHO reference laboratories according to EN standards (EN 1500). Their activity was found to be equivalent to the reference substance (isopropanol 60% v/v) for hygienic hand antisepsis.
70% ethanol is standard in most bio labs I’m familiar with.
 
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