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During the Covid-19 epidemic, choosing to wash hands with soap or hand sanitizer is more effective?

Soap and hand sanitizer are both effective, but there are times when you must use soap.

The World Health Organization said keeping hands clean, washing hands often with water and soap or alcohol-based hand sanitizer is one of the best measures that people need to do right now to prevent the Covid-19 epidemic.

Currently in Vietnam, many public places such as apartment buildings, offices, and shops have equipped alcohol-based hand sanitizers for users. However, some experts note that hand sanitizer is no substitute for washing hands with soap and water.

So what is going on? When can you use hand sanitizer, when is it necessary to wash with soap?

1. Soap's germ-removal mechanism

Soap is essentially a long-chain fatty acid molecule, in which the hydroxide group at one end has been removed by a base in a saponification reaction and replaced by a hydrophilic sodium molecule. The other end of the molecule is a hydrophobic end with nonpolar carbon and hydrogen atoms.

In a scenario where bacteria and viruses are on your hands, applying soap to your hands causes the hydrophobic end of the molecule to stick to the cell wall or envelope of the virus, where fatty lipid or protein membranes are located. After this process, bacteria and viruses surrounded by soap will turn into a spherical mass called micelles with the hydrophobic end facing in, and the hydrophilic end facing out.

Draining water after applying soap will roll up the hydrophilic ends of the micelles, carrying pathogens down the drain. Washing your hands with soap doesn't necessarily kill pathogens like the new coronavirus, but it will help you remove them from your hands.

Cơ chế hoạt động của xà phòng.
Cơ chế hoạt động của xà phòng.

2. Alcohol's virus inactivation mechanism

The alcohol-based agents used in hand sanitizers are usually isopropanol, ethanol, n-propanol, or a combination of 2 of these products. The antimicrobial activity of alcohol comes from its ability to denature and coagulate proteins. The microbial cells are then lysed and their metabolism disrupted.

As for the new corona virus, it has a "fatal" weakness so that it can be inactivated when exposed to alcohol. It is the shell of the nucleus. Alcohol can break this envelope, exposing the virus' genetic material and rendering it inactivated when it is no longer protected and no longer has receptors to infect cells.

This effect makes alcohol an effective pathogen inactivator to deal with the family of coronaviruses, including the SARS-CoV virus that caused the SARS outbreak in 2003 and the MERS virus that caused the Middle East Respiratory Syndrome in 2015. .

A study published in the Journal of Infectious Diseases confirmed that alcohol-based hand sanitizers (ethanol and isopropanol) are effective against enveloped viruses such as Ebola virus, Zika virus, SARS and MERS.

Cồn phá vỡ vỏ bọc của virus và khiến nó bị bất hoạt khi không còn còn các thụ thể để lây nhiễm tế bào.
Cồn phá vỡ vỏ bọc của virus và khiến nó bị bất hoạt khi không còn còn các thụ thể để lây nhiễm tế bào.

3. Which product should you choose during the Covid-19 epidemic?

With the above mechanisms, the World Health Organization said that both soap and alcohol-based hand sanitizer are the right options for the Covid-19 epidemic caused by the new corona virus. However, there are still some cases where you should choose soap over alcohol-based hand sanitizer.

That's when your hands have large or obvious stains that are visible to the naked eye, especially mucus or slime. A study by scientists from Tokyo Medical University found that handwashing instructions with alcohol-based hand sanitizer failed to inactivate the flu virus from mucus-contaminated hands.

Conventional hand sanitizer regulations only instruct people to rub their hands for 30 seconds. But new research shows it doesn't work.

The mucus on the hands acted as a hydrogel protecting the virus from alcohol and it took at least 4 minutes for the flu virus to be inactivated. If you rub your hands with hand sanitizer for 2 minutes when your hands are contaminated with mucus, the virus is still contagious.

The Centers for Disease Control and Prevention (CDC) also recommends that you use soap instead of alcohol-based hand sanitizer if your hands are greasy, slimy or greasy, such as after Food processing, sports, gardening or fishing…

In the case of dry hands or only non-greasy water, dry hand sanitizer is still effective in inactivating pathogens and new corona virus when rubbed correctly and enough for 30 seconds.

However, there are also some other disadvantages of hand sanitizer. That is, it is not able to destroy or inactivate non-enveloped viruses, such as the Poliovirus that causes polio.

Viruses that do not have a nuclear envelope have only a single layer of genetic material (DNA or RNA) that is tightly packed with proteins to form a solid particle, which alcohol-based hand sanitizers are less effective against.

In addition, alcohol-based hand sanitizers do not remove the toxicity of harmful chemicals such as pesticides or heavy metals. Therefore, in these cases, it is imperative that you wash your hands with soap and water to be safe.

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