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by elhudy 973 days ago
I was always under the impression that the purpose of soap isn’t to kill bacteria/viruses as the article implies, but to wash those thing off of your hands.

Was my impression wrong?

3 comments

Yes. If a pharmaceutical company's article (with better expertise in this area than the average HNer) isn't enough to convince someone here's an article from UNESCO:

https://www.unesco.org/en/articles/how-soap-kills-covid-19-h...

Confusingly, the one graphic in that article shows the soap binding to dirt and viruses and washing them off and away. It does not show the tearing/destruction of the lipid shells, though the article also talks about it.
The article itself has spelling and grammar mistakes in it. The lack of attention to detail does not build confidence in the content.

I was taught about the hydrophilic/hydrophobic nature of soaps and detergents in university decades ago; this is not new information, and is uncontroversial. As others have pointed out, it’s even easy to observe in simple home experiments.

I have never heard of soap disrupting the phospholipid shell of viruses; this is new and “interesting if true”.

The astoundingly bad handling of government communications during the pandemic makes me automatically skeptical of arguments from authority.

However, the takeaway of “wash your hands thoroughly to inhibit disease vector transmission” has amply been proven in the last century.

I'm not an expert on this either, but I think it's true that IN GENERAL a lot of the value in soap is just "debulking". It does do that very well.

But in the specific case of COVID-19 soap happens to also destroy the virus particles and that turns out to be pretty valuable too. :)

It's also important to know the current scientific consensus on how Covid spreads.

We now know that people who are infected with Covid emit viral particles into the air while breathing normally. Those viral particles can float in the air for hours and the people who inhale them become infected.

> The most common way COVID-19 is transmitted from one person to another is through tiny airborne particles of the virus hanging in indoor air for minutes or hours after an infected person has been there.

https://www.whitehouse.gov/ostp/news-updates/2022/03/23/lets...

Previously we thought the only transmission route was that infected people who sneeze or cough spray large droplets that fall out of the air quickly, and the people who touch surfaces contaminated by those droplets and later touch a mucous membrane become infected.

So Covid has fully airborne transmission like the measles, not a droplet based spread like the flu. Hand washing is an effective mitigation for a virus with a droplet based spread, but not a virus with an airborne spread.

The Whitehouse post linked above discusses the sorts of mitigations that can be effective against an airborne virus.

Non-expert, but soap disables not just COVID-19 but also most other viruses and bacteria.

Also, water alone does a lot to wash them away. Found this study of no-washing vs. water-washing vs. soap+water-washing with a quick search:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037063/

No washing: 44% of hands intentionally touching doorknobs and railings had bacteria

Water alone: 23%

Water + soap: 8%

(edit: line breaks)

A bit of both ? it messes with lipids, either your own lipid layer on the skin where dirt/microbes will lie, or actual cell membranes (also lipids).

Covid news claimed loud that soap will disrupt virus membranes, killing it.