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To reduce the risk of infection by viruses (including 2019-nCoV) the CDC suggests:

  • Wash your hands often with soap and water for at least 20 seconds. Use an alcohol-based hand sanitizer that contains at least 60% alcohol if soap and water are not available.
  • Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Avoid close contact with people who are sick.
  • Stay home when you are sick.
  • Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
  • Clean and disinfect frequently touched objects and surfaces.

To my knowledge most alcohol-based hand sanitizers use ethanol. In clinical settings sometimes isopropanol is also used.

Question: How exactly do alcohols, especially ethanol and isopropanol provide some disinfecting action against viruses? Are the virus particles simply dissolved? What happens?

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    $\begingroup$ Coronaviruses are enveloped viruses, so I would assume that the alcohol disrupts the membrane and thus strips away the molecules used for host cell recognition ... $\endgroup$
    – tyersome
    Commented Feb 2, 2020 at 0:47
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    $\begingroup$ @David No, it's specifically about the mechanism behind the effect of a particular chemical on a specific type of organism, and not about public hygiene. I've written the question carefully to make sure of that, I'm not certain you've read it through, or perhaps you are distracted by the background information. $\endgroup$
    – uhoh
    Commented Feb 2, 2020 at 9:15
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    $\begingroup$ @David If stripping away the molecules used for host cell recognition is the answer, then that is the answer and closing simply blocks people from posting it. $\endgroup$
    – uhoh
    Commented Feb 2, 2020 at 9:20
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    $\begingroup$ I think this is an absolutely valid question in my opinion. I disagree with David in that the mechanism is irrelevant; of course the way in which life is vulnerable to organic solvents is a biological question. However, to be fair I think the answer is rather simple and easy to google; ethanol lyses cells by rupturing the plasma membrane (which is made of ethanol-soluble lipids) and additionally denatures proteins. Alcohols can also dehydrate cells (substitute the water contents of a tissue) and have been as such used as fixatives. $\endgroup$
    – S Pr
    Commented Feb 3, 2020 at 13:39
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    $\begingroup$ This type of question is certainly on topic here since it's asking about how a chemical impacts a biological particle. There is no doubt about it, and the question should not be closed. @David this site is not just for questions related to a professional biologist's lab setting, but it's meant for (and certainly is used for) asking a wide range of biological questions. This includes questions about everyday people /situations such as hand sanitation, as long as they are asking about the biological characteristics, mechanisms, or impacts of that situation. Which is the case here. $\endgroup$
    – theforestecologist ♦
    Commented Mar 31, 2020 at 15:49

2 Answers 2

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Alcohols dissolve lipid bilayers

Many viruses have an outer lipid bilayer. Ethanol lyses cells, and in the same fashion damages membrane-bound viruses by rupturing the bilayer (which is made of ethanol-soluble lipids).

Alcohols misfold the protein coats of viruses

Additionally, alcohols denature proteins, which misfold in non-aqueous conditions. Some viral surface proteins are important for adhesion and attachment, and misfolding these renders the virus inactive. The total breakdown of viruses is essentially due to the misfolding of their protein coat (the capsid).

The same goes for bacteria

With the additional effect of dehydrating cells

Alcohols substitute the water contents of a tissue and have been as such used as fixatives. Common laboratory examples include methanol and ethanol.

Typically, 70% (140 proof) ethanol is used for bench wiping to kill or inactivate microbes. This includes viruses.

This is all standard, common, easily and readily accessible knowledge. Here's a bonus source.

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  • $\begingroup$ (1) Read closer, I've addressed viruses. Admittedly it is a short answer, but I don't think it can be made substantially better. I could format the viral part to bold font if you really think it will help... (2) All that applies for ethanol and methanol apply for isopropanol too. Isopropanol is used in cleaning work surfaces; methanol is too toxic to humans for that purpose. $\endgroup$
    – S Pr
    Commented Feb 3, 2020 at 15:41
  • $\begingroup$ We expect you to show a minimum attempt at your own research, and explain where you remain unclear about something. This is the most standard textbook, easy-to-search query. You have clearly not thought to use a search engine, and you have also not consulted the search bar on this stack yet. You'll find an answer anywhere if you look. I also urge you to read this. I'm sorry you are so hurt about my inclusion of membrane-bound microbes; viruses too sometimes harbor membrane envelopes. Alas! $\endgroup$
    – S Pr
    Commented Feb 4, 2020 at 8:52
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    $\begingroup$ From wikipedia: A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. Viruses don't have a lipid layer. In addition, I am removing your last comment S Pr - be nice svp. $\endgroup$
    – AliceD ♦
    Commented Feb 4, 2020 at 12:33
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    $\begingroup$ Thanks for the edit, it looks great! $\endgroup$
    – uhoh
    Commented Feb 4, 2020 at 14:48
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A comment on the question suggests that several infectious viruses (including 2019-nCoV) are envelope viruses and that alcohol can "strip away the molecules used for host cell recognition". Viral envelopes (are), typically derived from portions of the host cell membranes.

A key component of these envelopes are of course lipids.

From Antiviral activity of alcohol for surface disinfection:

Antiviral activity and the viral envelope

Because of the structure and composition of the different virus families, viruses react differently to the action of disinfectants. From a disinfectant point of view, the presence or absence of an envelope is the most important trait of a virus. Lipid-enveloped virus families are, generally, susceptible to many disinfectants, alcohols included. The higher the lipid content and the larger the virion itself, the more susceptible the virus is.

Many (but not all) of the so called small `naked' virus families (e.g. adeno, parvo, picorna viruses causing a.o. poliomyelitis,hepatitis A, hand foot and mouth disease, common cold) that do not possess an envelope are quite resistant to common disin-fectants, alcohols included (6, 7).

Fortunately, the herpes viruses (herpes simplex I and II, 5-8,varicella, Epstein Barr); paramyxo viruses (measles, mumps);retro viruses (HIV, AIDS); hepadna viruses (hepatitis B); coronaviruses (SARS) are lipid-enveloped virus families that are, generally, susceptible to the disinfectant activity of alcohols(5, 8).

5 JuÈlich W-D, v. Rheinbaben F, Steinmann J, Kramer A. On the virucidal efficacy of chemical and physical disinfectants or disinfection procedures. Hyg Med 1993; 18: 303-26.

6 Tyler R, Ayliffe GA, Bradley C. Virucidal activity of dis-infectants: studies with the poliovirus.J Hosp Infect 1990; 15:339-45.

7 Mbithi JN, Springthorpe VS, Sattar SA. Chemical disinfection of hepatitis A virus on environmental surfaces. Appl Environ Microbiol 1990; 56:3601-4.

8 Croughan WS, Behbehani AM. Comparative study of inactivation of herpes simplex virus types 1 and 2 by commonly used antiseptic agents.J Clin Microbiol 1998; 26: 213-5.

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