Inactivating Coronavirus on Skin and Surfaces

Coronavirus: Why does soap inactivate the virus on skin, but not on surfaces?

Soap is a highly effective agent in inactivating the coronavirus on skin due to its unique chemical properties and the way it interacts with the virus particles. However, the situation is slightly different when it comes to surfaces.

To understand this, we need to delve into the structure of the coronavirus. The virus consists of a lipid envelope that surrounds its genetic material. This envelope is made up of a layer of fatty molecules called lipids. These lipids are soluble or can dissolve in fats and oils but are not soluble in water

When soap is applied to the skin, it acts as a surfactant. Surfactants have a dual nature since they have both hydrophilic (water-loving) and hydrophobic (water-repelling) properties. The hydrophilic head of the soap molecule is attracted to water, while the hydrophobic tail is repelled by it

When you rub soap on your hands, the hydrophilic heads of the soap molecules surround the droplets of water, while the hydrophobic tails stick out into the air. This forms structures called micelles, where the tails form a protective layer around tiny water droplets. When you lather and scrub, these micelles trap dirt, bacteria, and viruses, including the coronavirus, within the non-polar (hydrophobic) part of their structure

Now, here comes the crucial part. The hydrophobic part of the soap molecules can easily break down the lipid envelope of the coronavirus. This is because the lipid envelope of the virus is also non-polar, and when the hydrophobic tails of the soap molecules encounter the viral envelope, they disrupt its structure, essentially destroying the virus

On the other hand, when soap is applied to surfaces, it doesn’t have the same agitation or rubbing action as when you wash your hands. Also, surfaces are often more varied and can have different textures, which can make it harder for the soap to spread evenly and interact effectively with the virus particles. Additionally, surfaces may have microscopic crevices, pores, or irregularities where the virus can hide and protect itself from the soap

Therefore, while soap is still potentially effective at inactivating the virus on surfaces, thorough and consistent cleaning, coupled with appropriate disinfectants, is necessary to ensure complete removal and inactivation of the virus

It’s important to note that soap is exceptional for handwashing because it not only breaks down the virus envelope but also physically removes the virus from your skin when you rinse your hands. This, combined with the recommended 20-second handwashing duration, helps to greatly reduce the risk of transmitting the virus

In conclusion, soap inactivates the coronavirus on skin due to its ability to break down the lipid envelope of the virus by forming micelles. However, on surfaces, soap may have limited effectiveness, and additional cleaning and disinfection measures are recommended for thorough virus removal

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