A practical guide for the home
First off, there are plenty of other useful sources out there that explain the importance of washing your hands and how to wash your hands correctly, so this paper will not cover this; but please wash your hands correctly, for 20 seconds and often! Instead, this paper will cover other aspects of managing the spread of SARs-CoV-2, that I personally believe [next to hand washing, our first line of defence] are the most effective ways to combat the spread of CoVid-19*. At the end of this article, there is also a recipe for homemade hand sanitiser with a final concentration of 83.12% alcohol.
(*Please note, I am not a doctor, nor am I a medical professional but I am a scientist (published in peer review) I have a B.Env.Sci (Hons) and I am currently seeking supervisor for a PhD that focuses on zoonotic risk factors of human malaria. I have extensive knowledge of infection dynamics and pathogen control, especially parasites both botanical and blood. I am also highly skilled at both conducting a search of, as well as interpreting peer-review scientific literature, particularly literature in the biosciences and biomedical sciences, including virology. The following information you are being provided with is correct for its time and is the best information available to scientists at this time).
Disinfecting surfaces to prevent the spread of CoVid-19
What you should use
I am writing this guide in response to an in-depth review paper recently published by Kampf and Steinmann (2020), which demonstrates what surface disinfections are likely to inactivate SARs-CoV-2 using model pathogens that are most like SARs-CoV-2 and therefore more than likely can be used to prevent the spread of CoVid-19 (see table 1 below or table 2 of the article). To inactivate the virus on surfaces [number of active versus inactive virion/single virus particles] in the shortest and therefore most effective time frame possible, you need pure rubbing alcohol, 95% ethanol (which is simply methylated spirits) or failing that at least 71% or higher isopropyl alcohol (which Aussies can buy at Bunnings or hardware stores).
The review by Kampf and Steinmann (2020) indicate, both isopropyl alcohol and ethanol (methylated spirits) with a concentration that is >70% (greater than) will inactivate the virus in 30 seconds. Unfortunately, the commercially bought product Isocol is only 64%, so it’s also ineffective for this time frame, but see the tables below to see other time frames to use on less frequented surfaces of the home. Thus this is where good old ‘metho’, for us Aussies saves the day. Therefore the study indicates that you should use these products to wipe down surfaces, making sure to saturate the surface, so it doesn’t evaporate too quickly. It is really important to make sure the alcohol doesn’t evaporate before the time it takes to inactivate the virus, this means you really need to wet/saturate the surface, so don’t forget!
What you shouldn’t use
I’m only going to say this once, do not use the following. Do not use benzalkonium chloride or chlorhexidine, (the main ingredients in disinfectant or disinfectant wipes) unless they have concentrations of at least 0.1% and they will be hard to come by at this stage now anyway! It’s funny (in a morbid way) everyone who panic bought disinfectant wipes have no idea that these products do not kill the virus- they are in fact wasting their time! This is because most disinfectant wipes are only 0.04% benzalkonium chloride, or 0.02% chlorhexidine, so in fact, it can take up to 10 minutes to kill it when used on surfaces. So unless the surface is literally wet and saturated for 10 minutes, it is still contaminated!
Put simply, I wouldn’t even use them if I were you, the risk is too high! It’s a gamble we can’t afford to make. Even more shocking, is that if these concentrations are even less than 0.04% such as 0.01% then forget it, these concentrations do not work at all! In fact, it will take 3 days to kill the virus (the same time it takes for the virus to die anyway!) so don’t use them, it is giving you a dangerous, false sense of security and it is the literal equivalent to doing nothing! Additionally, if you want to know how long the virus survives on surfaces, the paper also outlines how long the virus survives on different surfaces i.e. clothes, paper, steel etc… (see table 2 below or table 1 of the paper).
It is important to understand your hands (whilst organic) are also considered a ‘surface’ so in the event of an emergency (such as if you know you have directly come into contact with someone who is infected) you can ‘disinfect’ your hands or other parts of your body. So you can essentially submerge your hands in methylated spirits (95% ethanol) or 100% isopropyl alcohol for at least 30 seconds, and it will reduce the viral load to what is known as undetectable/safe levels. Basically, you’ll reduce it to nothing. However, the catch with that is, that it will dry out your hands! So best to only do this in an emergency, and make sure you use a moisturiser afterwards! Which brings us to my next point…
Now, I spent a bit of time working this out and came up with my own recipe to make it based on the recommendations from WHO [but if there is anyone out there who feels the ratios are wrong then please correct me]. Here is a break-down of why I strongly believe commercial hand sanitisers are probably no-where near as effective as they are believed to be! A lot of doctors and medical professionals are saying you need a hand sanitiser that is at least 60% this is completely incorrect, it’s actually 70% when it comes to SARs-CoV-2, (see Kampf and Steinmann 2020). Why are doctors saying 60%? Because these professionals are misinformed and they have NOT read the latest studies in peer review! Peer review, for anyone who doesn’t know, is basically the latest up to date knowledge in the sciences that other scientists (usually experts) have agreed and approved to.
The science of peer review is moving really fast at the moment. Unfortunately, it is becoming increasingly apparent to me, that more often than not, doctors and health workers DO NOT read peer review and so they are NOT up to date up with the latest scientific studies, which is critical in times like a global pandemic! How do I know this? Well because every up to date peer-review study I read, does not reflect knowledge or advice given to the public. In fact, according to Kampf and Steinmann (2020) concentrations of alcohol at 70% is not even really that effective against SARs-Cov-2 at all! Yes, it will reduce the viral load but the study demonstrates that with concentrations of 70% the virus only becomes inactive after 10 minutes, and that’s nothing to sneeze at, literally. This means the time it takes for a commercial hand sanitiser to evaporate is probably less than the time it takes to inactivate the virus to safe levels.
This might shock you but…interestingly, as I said earlier, if the concentration of alcohol is >70% it is the most effective. But something really interesting is that if we increase it from 71-75%, then the viral load is reduced to almost nothing, in… wait for it… 30 seconds! So that’s 30 seconds versus 10 minutes, which is obviously a no-brainer! So basically at 70%, you’d need to stick your hand in the hand sanitiser for 10 minutes to really get the full effect! In essence, it’s pretty useless. Whereas we know that with concentrations >70% (table 1) we see a massive reduction in the time it takes to reduce the viral load; and at 75% the viral load is reduced to undetectable levels in just 30 seconds! And here’s the really really interesting thing, most commercially produced sanitisers are a mere 70%, so isn’t it interesting that as soon as the threshold of 70% has been reached, you see a huge jump in the time it takes to reduce the viral load!?
This sort of result I would argue, suggests viruses like SARs-Cov-2 and new strains emerging from it, can develop some sort of resistance to commonly used concentrations of commercially available hand sanitiser and or household disinfectants! However, this may just be an artefact of the fact that products and their concentrations, were designed around studies such as these. Thus, is what lead us to design these effective products in the first place, however, it is a compelling argument to suggest resistance, none the less!
Now if you scroll your finger up to the top of table 2, you’ll notice the higher the concentration of alcohol the better, so theoretically you’d want a hand sanitiser with the highest possible concentration of alcohol, something that reduces the viral load in the shortest possible time frame but also doesn’t evaporate before this time. Kampf and Steinmann (2020) demonstrated saturation of the virus using differing concentrations of alcohol starting at 75-78% right up to 95-100% reduce the viral load to almost nothing in 30 seconds.
So in terms of hand sanitiser you really need something that is >71%, and it just so happens that WHO recommends a final product which is 80%. However, as mentioned earlier, we can’t keep dousing our hands in high concentrations of alcohol, not only will they will dry out but you’ll have to use a lot! Plus to get a high concentration of alcohol in that final product you need a high concentration to begin with. So we need something to both counteract that dryness and keep the concentration of alcohol at an effective level-to reduce the viral load. We don’t want to dilute it past the point of its effectiveness. To do this, we need to dilute it by adding an emollient which will counteract that dryness but also keep it lingering longer. Basically, when you are dealing with alcohol in high concentrations, you need to make sure the dilution factor will be no less than the final concentration that is required to reduce the viral load i.e. must be >71%. Therefore ideally at least 75% for isopropyl alcohol or 78% for ethanol to reach the 30-second mark (see table 1). Obviously, we don’t want to be only slightly better than commercial products, we want to be better! So to ensure the most effective outcome, we need to ensure we start with an initial concentration of 95% so that our final product is at least 80%, as recommended by WHO.
Table 1 Kampf and Steinmann (2020) demonstrate, it is likely that SARs-Cov-2 inactivation is most effective at concentrations of alcohol >70% (yellow) whereas surface disinfectants chlorhexidine and benzalkonium chloride (green) are ineffective at concentrations <0.2%.
Table 2 As demonstrated by Kampf and Steinmann (2020) it is likely that SARs-CoV-2 will follow a similar time frame to other pathogens.
Kampf, G., Todt, D., Pfaender, S., & Steinmann, E. (2020). Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents. Journal of Hospital Infection. [Link to full article] https://www.sciencedirect.com/science/article/pii/S0195670120300463?fbclid=IwAR0WKiJmkj2jvsrbJTe_FeCjFZRfFPAy9T5EHTOw571F-FDP-EdLdTmv8ZA
World Health Organisation https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf
N.F.Clark’s home-made hand sanitiser
*Generally speaking to slightly reduce the concentration you must have more alcohol than your solvent/emollient, generally 3 parts alcohol, 1 part the solvent/emollient. Alcohol without solvents are really tough on our hands so adding the glycerin will ensure your hands are quite moisturised and don’t dry out. Please also note that this recipe does not include hydrogen peroxide, since it is not essential to the process*
You will need:
- Ethanol alcohol/methylated spirits 950 ml/L (must be 95% concentration)
- Pure glycerine or glycerol
Methylated spirits (210 ml)
Glycerin (30ml) equiv. 1/8 cup
Pour in 210ml of methylated spirits in a clean, dry glass bowl or jug, then add 30ml of glycerin and stir well. For the equation and for the concentration to work, your final mixture must add up to 240ml. Pour it into a spray or pump bottle and you’re done! You can also double this recipe to make more.
And that’s it, now you have a home-made hand sanitiser that is at least 10% more effective than store bought*, as peer review studies indicate concentrations such as this are far more effective at reducing the viral load than their commercially produced counterparts.
Of course that aside, nothing is more effective than washing your hands; and no hand sanitiser should be used unless in the absence of soap and water!
Chemical equation this recipe is based on: C1V1=C2V2
950×3.5/4 (which is a little bit over 3/4cup) which is the equiv. to 95%x210/240= 83.12% which is also equiv. to… 210ml= 3 quarter cups+ 1/8 of a cup… but since the final product must add up to 240ml; this means to reduce the concentration of ethanol to 83.12% then we need 30 ml of our emollient which is 1/8 of a cup of glycerin.
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