Hand Washing and Sanitizing to Inactivate COVID-19 Coronavirus

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My recipes for DIY hand sanitizer and surface disinfectant for SARS-CoV-2.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Because it’s so difficult for people to keep themselves from unconsciously touching their face, it’s critical to be able to disinfect your hands by washing your hands with soap and water, sudsing up for at least twenty seconds. It’s not clear why the CDC chose that duration. There is evidence that if you have bacteria-contaminated meat debris on your hands, washing with soap for 20 seconds is preferable to without soap for 5 seconds. Duh, but most of the published soap-to-soap studies compared 15 seconds to 30 seconds, and have found there does not appear to be a meaningful difference between 15 and 30. The recommendation to wash your hands with soap and water for 20 seconds was likely made to encourage sufficient hand coverage.

Using invisible fluorescent or UV dyes, researchers have found the most frequently missed areas when washing your hands include the fingertips, thumbs, and backs of hands. So it’s good to get into a habit of going through all the steps to cover all the surfaces instead of just happy birthday-ing your way through the same motions. Makes the time go a little faster if you have a routine down. Oh, and artificial nails are discouraged, as they’ve been shown to interfere with handwashing efficacy.

Should you use hot water for hand-washing? When I gave a webinar on this topic and asked people to vote, about 1,000 of the 5,000 participants got it wrong. Contrary to popular belief, there is no need to use hot water. Studies going back more than eighty years show no benefit in germ removal when using hot water over cool water, and frequent hand-washing with hot water may increase the risk of skin irritation. (As an aside, the false belief that warm or hot water is preferable may also add an additional million metric tons of carbon, through energy usage, to the atmosphere from the United States alone every year.) The use of hand lotions or creams has been shown to help protect hands from the minor skin damage associated with frequent hand-washing, at any temperature.

Now, for healthcare professionals, the World Health Organization recommends the use of alcohol-based hand sanitizer—whether gel, foam, or spray—over hand-washing for routine hand disinfection, that is, when hands are not visibly soiled. And, so does the CDC. What type of hand hygiene is recommended? The CDC continues to recommend the use of alcohol-based hand rubs as the primary method for hand hygiene. Why? Part of the reason is greater compliance compared to hand-washing with soap and water.

Just as we can’t rely on people to not touch their face, we can’t rely on people to wash their hands properly. In a family medicine clinic, fewer than 1 in 10 hand-washings met even a 10-second version of the CDC standards. Less than 10%. In contrast, more than 8 out of 10 instances of disinfections with alcohol-based cleansers hit the mark, which simply entails rubbing your hands together until the alcohol covers all surfaces of the hands and waiting for product to dry completely.

Normally cheap and ubiquitous at dollar stores everywhere, hand sanitizer was one of the first items to disappear from store shelves and internet inventories as the COVID-19 crisis loomed. Anyone heeding my decade-old advice on pandemic preparedness to stock up should already be well supplied, but if not, you can make your own.

Although 40% alcohol (either ethanol, regular drinking alcohol, or isopropyl, found in rubbing alcohol) has been found to topically kill some enveloped viruses, like SARS or MERS, others, like hepatis C and ebolavirus, require 60% alcohol or more (as measured on a volume rather than weight basis). That’s why recommended alcohol concentrations in hand sanitizers range from a minimum of 60%, recommended by the CDC, to 75 or 80% recommended by the WHO, because they want to account for a wide variety of pathogens. But what do we need specifically for COVID-19?

On Snopes, the social media meme that a “homemade hand sanitizer made with Tito’s Vodka can be used to fight the new coronavirus” was ruled as false, since most vodkas (including Tito’s) only contain 40% alcohol, and Snopes cited the CDC’s 60% minimum rule. However, the CDC has since published evidence by a respected team of researchers, funded by the European Commission and German government, finding that the COVID-19 virus could be inactivated within 30 seconds by just 30% alcohol (either ethyl alcohol or isopropyl alcohol). So, like 30% alcohol, 70% water wiped out the COVID-19 coronavirus.

In that case, a variety of hard liquors or “spirits” could indeed be repurposed for use as hand sanitizers for COVID-19, either straight or even diluted to a certain extent. Most vodka, rum, brandy, tequila, gin, and whisky exceed 30% alcohol by volume. So, from a COVID-19 standpoint, there are still bottles of hand sanitizer available on the shelves, just on those of liquor stores rather than drug stores.

It’s funny, past guests in my home are surprised to see so many big plastic bottles of cheap, 120-proof vodka in my wine rack (especially for someone who doesn’t drink at all). I stocked up a decade ago, following my own pandemic prep guidelines to make extra DIY, budget-friendly hand sanitizer for the next outbreak. And, with the current virus, it looks like I may be able to even cut it 50:50. Note that 30 percent alcohol isn’t enough to kill many other pathogens; so, I’d still recommend 60–80 percent alcohol products if you can get them. So, you can have “one rub to rule them all.” But, in a pinch during this crisis, it can be comforting to know there may be some alternatives.

Both the WHO and interim FDA guidelines for those making their own hand sanitizer include the use of an emollient (1.45% by volume glycerol, also known as glycerine) to help keep the alcohol from drying the skin, as well as a preservative (0.125% by volume of the standard over-the-counter 3% hydrogen peroxide) to kill any contaminating bacteria spores. What’s important for inactivating the virus, though, is the alcohol content.

So, here’s the recipe for making a gallon. Assuming 30% alcohol is sufficient, and you had all of the ingredients, you could make a gallon of COVID-19 hand sanitizer by combining 12 cups of an 80-proof liquor with a quarter cup of glycerin (which is also spelled glycerine with an e, or glycerol), and a teaspoon of regular strength hydrogen peroxide, and then just fill the rest of a gallon container with water, and nothing else. The addition of a gelling agent, such as aloe vera, is not recommended, as it might compromise antiviral efficacy.

You could also quarter the recipe to make a quart (three cups spirits, a tablespoon glycerine, quarter teaspoon hydrogen peroxide, and water). But, no need to get so fancy. For this particular virus, the easiest method would probably be to just use the 80-proof liquor straight up as a hand-sanitizing rub. Just pour it into a squirt or spray bottle and apply enough to completely cover all surfaces of your hands, and then rub together for 30 seconds until they’re dry.

On inanimate surfaces, bleach is recommended for disinfection (1 part household bleach diluted in 49 parts water); so, about 1 teaspoon bleach per cup of water, and nothing else. NEVER mix bleach with any other cleanser. Bleach reacts with ammonia (found in many glass cleaners) to create hazardous gases called chloramines, and reacts with acids (like vinegar, or some toilet bowl and drain cleaners, and automatic dishwashing detergents) to create chlorine gas, which is also toxic.

Note the more typical 1:100 dilution of bleach, as sometimes recommended by the manufacturer on the back of the bottle, may not be sufficient, based on data from other coronaviruses. That’s why it seems more appropriate to recommend a dilution of 1:50 of standard bleach in the coronavirus setting. Note this 1:50 recommendation is for standard bleach, meaning 5% sodium hypochlorite. Read the label. If you have 2.5% hypochlorite bleach, you’d have to use two teaspoons per cup, and if you have 10% hypochlorite bleach, you’d only need a half teaspoon per cup.

The bleach solution can be used within a month of preparation, if stored in a closed, opaque container at room temperature. Though it’s recommended that you leave it on the surface you’re disinfecting for at least ten minutes, when put to the test, five minutes at that concentration was found to wipe out the COVID virus. Note that surfaces grossly contaminated by bodily secretions, meaning visibly contaminated with snot or blood or poop, may require a stronger bleach solution (one part standard bleach to nine parts water, left for 10 minutes). So, that would be five teaspoons of bleach, for inanimate surfaces that are visibly contaminated with bodily fluids, per cup of water.

Alcohol can be used on surfaces that aren’t suitable for bleach, such as metal, which bleach can stain or even corrode. Sufficiently concentrated povidone-iodine, chloroxylenol, and chlorhexidine have also been shown to clear the virus within five minutes.

Although the EPA suggests common quaternary ammonium compounds should be effective, I found an old paper…that reported they were “virtually useless” as a sole disinfecting agent against viruses dried on surfaces,––ncluding one of the common cold human coronaviruses. Though when put to the test, a 0.1% solution of benzalkonium chloride has been found to be effective against SARS-CoV-2 within five minutes. But just a straight soap solution (1 part hand soap, 49 parts water) appeared to take as long as 15 minutes to inactivate it. That would be one teaspoon liquid hand soap in a cup of water. Dishwashing detergent appears to work faster, at least against the SARS virus, with the same 1:50 dilution of dish soap to water working within five minutes. No word yet on dish soap and the SARS 2 coronavirus

Within 30 seconds, Lysol disinfectant spray and a 1:64 dilution of Pine-Sol destroy murine hepatitis virus, a mouse coronavirus that’s used as a potential surrogate for human coronaviruses (since it’s safer to handle in the lab than something like SARS), but Lysol and Pine-Sol have yet to be tested against the COVID-19 virus. In a pinch, wine vinegar (6% acid) was shown to destroy more than 99.9 percent of the SARS virus within 60 seconds, but, again, no word on the new virus.

The most macabre decontamination advice I found was published in the Journal of the Chinese Medical Association: “Corpses… should be burned or buried deep.”

Please consider volunteering to help out on the site.

Motion graphics by AvoMedia

Image credit: Bowonpat via Adobe Stock Photos. Image has been modified.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Because it’s so difficult for people to keep themselves from unconsciously touching their face, it’s critical to be able to disinfect your hands by washing your hands with soap and water, sudsing up for at least twenty seconds. It’s not clear why the CDC chose that duration. There is evidence that if you have bacteria-contaminated meat debris on your hands, washing with soap for 20 seconds is preferable to without soap for 5 seconds. Duh, but most of the published soap-to-soap studies compared 15 seconds to 30 seconds, and have found there does not appear to be a meaningful difference between 15 and 30. The recommendation to wash your hands with soap and water for 20 seconds was likely made to encourage sufficient hand coverage.

Using invisible fluorescent or UV dyes, researchers have found the most frequently missed areas when washing your hands include the fingertips, thumbs, and backs of hands. So it’s good to get into a habit of going through all the steps to cover all the surfaces instead of just happy birthday-ing your way through the same motions. Makes the time go a little faster if you have a routine down. Oh, and artificial nails are discouraged, as they’ve been shown to interfere with handwashing efficacy.

Should you use hot water for hand-washing? When I gave a webinar on this topic and asked people to vote, about 1,000 of the 5,000 participants got it wrong. Contrary to popular belief, there is no need to use hot water. Studies going back more than eighty years show no benefit in germ removal when using hot water over cool water, and frequent hand-washing with hot water may increase the risk of skin irritation. (As an aside, the false belief that warm or hot water is preferable may also add an additional million metric tons of carbon, through energy usage, to the atmosphere from the United States alone every year.) The use of hand lotions or creams has been shown to help protect hands from the minor skin damage associated with frequent hand-washing, at any temperature.

Now, for healthcare professionals, the World Health Organization recommends the use of alcohol-based hand sanitizer—whether gel, foam, or spray—over hand-washing for routine hand disinfection, that is, when hands are not visibly soiled. And, so does the CDC. What type of hand hygiene is recommended? The CDC continues to recommend the use of alcohol-based hand rubs as the primary method for hand hygiene. Why? Part of the reason is greater compliance compared to hand-washing with soap and water.

Just as we can’t rely on people to not touch their face, we can’t rely on people to wash their hands properly. In a family medicine clinic, fewer than 1 in 10 hand-washings met even a 10-second version of the CDC standards. Less than 10%. In contrast, more than 8 out of 10 instances of disinfections with alcohol-based cleansers hit the mark, which simply entails rubbing your hands together until the alcohol covers all surfaces of the hands and waiting for product to dry completely.

Normally cheap and ubiquitous at dollar stores everywhere, hand sanitizer was one of the first items to disappear from store shelves and internet inventories as the COVID-19 crisis loomed. Anyone heeding my decade-old advice on pandemic preparedness to stock up should already be well supplied, but if not, you can make your own.

Although 40% alcohol (either ethanol, regular drinking alcohol, or isopropyl, found in rubbing alcohol) has been found to topically kill some enveloped viruses, like SARS or MERS, others, like hepatis C and ebolavirus, require 60% alcohol or more (as measured on a volume rather than weight basis). That’s why recommended alcohol concentrations in hand sanitizers range from a minimum of 60%, recommended by the CDC, to 75 or 80% recommended by the WHO, because they want to account for a wide variety of pathogens. But what do we need specifically for COVID-19?

On Snopes, the social media meme that a “homemade hand sanitizer made with Tito’s Vodka can be used to fight the new coronavirus” was ruled as false, since most vodkas (including Tito’s) only contain 40% alcohol, and Snopes cited the CDC’s 60% minimum rule. However, the CDC has since published evidence by a respected team of researchers, funded by the European Commission and German government, finding that the COVID-19 virus could be inactivated within 30 seconds by just 30% alcohol (either ethyl alcohol or isopropyl alcohol). So, like 30% alcohol, 70% water wiped out the COVID-19 coronavirus.

In that case, a variety of hard liquors or “spirits” could indeed be repurposed for use as hand sanitizers for COVID-19, either straight or even diluted to a certain extent. Most vodka, rum, brandy, tequila, gin, and whisky exceed 30% alcohol by volume. So, from a COVID-19 standpoint, there are still bottles of hand sanitizer available on the shelves, just on those of liquor stores rather than drug stores.

It’s funny, past guests in my home are surprised to see so many big plastic bottles of cheap, 120-proof vodka in my wine rack (especially for someone who doesn’t drink at all). I stocked up a decade ago, following my own pandemic prep guidelines to make extra DIY, budget-friendly hand sanitizer for the next outbreak. And, with the current virus, it looks like I may be able to even cut it 50:50. Note that 30 percent alcohol isn’t enough to kill many other pathogens; so, I’d still recommend 60–80 percent alcohol products if you can get them. So, you can have “one rub to rule them all.” But, in a pinch during this crisis, it can be comforting to know there may be some alternatives.

Both the WHO and interim FDA guidelines for those making their own hand sanitizer include the use of an emollient (1.45% by volume glycerol, also known as glycerine) to help keep the alcohol from drying the skin, as well as a preservative (0.125% by volume of the standard over-the-counter 3% hydrogen peroxide) to kill any contaminating bacteria spores. What’s important for inactivating the virus, though, is the alcohol content.

So, here’s the recipe for making a gallon. Assuming 30% alcohol is sufficient, and you had all of the ingredients, you could make a gallon of COVID-19 hand sanitizer by combining 12 cups of an 80-proof liquor with a quarter cup of glycerin (which is also spelled glycerine with an e, or glycerol), and a teaspoon of regular strength hydrogen peroxide, and then just fill the rest of a gallon container with water, and nothing else. The addition of a gelling agent, such as aloe vera, is not recommended, as it might compromise antiviral efficacy.

You could also quarter the recipe to make a quart (three cups spirits, a tablespoon glycerine, quarter teaspoon hydrogen peroxide, and water). But, no need to get so fancy. For this particular virus, the easiest method would probably be to just use the 80-proof liquor straight up as a hand-sanitizing rub. Just pour it into a squirt or spray bottle and apply enough to completely cover all surfaces of your hands, and then rub together for 30 seconds until they’re dry.

On inanimate surfaces, bleach is recommended for disinfection (1 part household bleach diluted in 49 parts water); so, about 1 teaspoon bleach per cup of water, and nothing else. NEVER mix bleach with any other cleanser. Bleach reacts with ammonia (found in many glass cleaners) to create hazardous gases called chloramines, and reacts with acids (like vinegar, or some toilet bowl and drain cleaners, and automatic dishwashing detergents) to create chlorine gas, which is also toxic.

Note the more typical 1:100 dilution of bleach, as sometimes recommended by the manufacturer on the back of the bottle, may not be sufficient, based on data from other coronaviruses. That’s why it seems more appropriate to recommend a dilution of 1:50 of standard bleach in the coronavirus setting. Note this 1:50 recommendation is for standard bleach, meaning 5% sodium hypochlorite. Read the label. If you have 2.5% hypochlorite bleach, you’d have to use two teaspoons per cup, and if you have 10% hypochlorite bleach, you’d only need a half teaspoon per cup.

The bleach solution can be used within a month of preparation, if stored in a closed, opaque container at room temperature. Though it’s recommended that you leave it on the surface you’re disinfecting for at least ten minutes, when put to the test, five minutes at that concentration was found to wipe out the COVID virus. Note that surfaces grossly contaminated by bodily secretions, meaning visibly contaminated with snot or blood or poop, may require a stronger bleach solution (one part standard bleach to nine parts water, left for 10 minutes). So, that would be five teaspoons of bleach, for inanimate surfaces that are visibly contaminated with bodily fluids, per cup of water.

Alcohol can be used on surfaces that aren’t suitable for bleach, such as metal, which bleach can stain or even corrode. Sufficiently concentrated povidone-iodine, chloroxylenol, and chlorhexidine have also been shown to clear the virus within five minutes.

Although the EPA suggests common quaternary ammonium compounds should be effective, I found an old paper…that reported they were “virtually useless” as a sole disinfecting agent against viruses dried on surfaces,––ncluding one of the common cold human coronaviruses. Though when put to the test, a 0.1% solution of benzalkonium chloride has been found to be effective against SARS-CoV-2 within five minutes. But just a straight soap solution (1 part hand soap, 49 parts water) appeared to take as long as 15 minutes to inactivate it. That would be one teaspoon liquid hand soap in a cup of water. Dishwashing detergent appears to work faster, at least against the SARS virus, with the same 1:50 dilution of dish soap to water working within five minutes. No word yet on dish soap and the SARS 2 coronavirus

Within 30 seconds, Lysol disinfectant spray and a 1:64 dilution of Pine-Sol destroy murine hepatitis virus, a mouse coronavirus that’s used as a potential surrogate for human coronaviruses (since it’s safer to handle in the lab than something like SARS), but Lysol and Pine-Sol have yet to be tested against the COVID-19 virus. In a pinch, wine vinegar (6% acid) was shown to destroy more than 99.9 percent of the SARS virus within 60 seconds, but, again, no word on the new virus.

The most macabre decontamination advice I found was published in the Journal of the Chinese Medical Association: “Corpses… should be burned or buried deep.”

Please consider volunteering to help out on the site.

Motion graphics by AvoMedia

Image credit: Bowonpat via Adobe Stock Photos. Image has been modified.

Doctor's Note

This is the 12th in my 17-video series on pandemics and COVID-19. If you missed any, check out:

We’ll round out the series with:

You can also get them all right now in a free (for a limited time!) digital download here. 

Find the recipes for sanitizer on my COVID-19 resource page.

Update: As of July 6, the EPA has approved two Lysol products for use on COVID-19. See their statement here.

If you want a deeper dive, check out my new book How to Survive a Pandemic (note: all my proceeds from this book are donated to pandemic prevention charities).

If you haven't yet, you can subscribe to our free newsletter. With your subscription, you'll also get notifications for just-released blogs and videos. Check out our information page about our translated resources.

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