[AllUsers-ISR] Gestão de Emergência Covid-19 no ISR + Estrategias para minimizar riscos - Soap is the best, but do please use alcohol-based sanitiser when soap is not handy or practical

[Aníbal T. de Almeida]

Caros Investigadores,

qui vai informaçao adicional  com a mensagem explicada em baixo -

*Soap is the best, but do please use alcohol-based sanitiser when soap 
is not handy or practical*

Saudaçoes cordiais,

Anibal Traça de Almeida

Director
ISR - University of Coimbra
Dep. Electrical Engineering , Polo II
3030 Coimbra, Portugal
www.isr.uc.pt

**********************************************************************************************************************************************************************

*The science of soap – here’s how it kills the coronavirus *

Palli Thordarson <https://www.theguardian.com/profile/pall-thordarson> 
Thu 12 Mar 2020 09.40 GMT

Alcohol-based disinfectants are also effective, but soap is a highly 
efficient way of killing the virus when it’s on your skin

<https://www.theguardian.com/commentisfree/2020/mar/12/science-soap-kills-coronavirus-alcohol-based-disinfectants#img-1>

Man and young child washing hands with 
soap<https://www.theguardian.com/commentisfree/2020/mar/12/science-soap-kills-coronavirus-alcohol-based-disinfectants#img-1>

‘Soap dissolves the fat membrane of the virus – and the virus falls 
apart like a house of cards and dies.’ Photograph: Flashpop/Getty Images

Viruses can be active outside the body for hours, even days. 
Disinfectants, liquids, wipes, gels and creams containing alcohol are 
all useful at getting rid of them – but they are not quite as good as 
normal soap.

When I shared the information above 
<https://twitter.com/PalliThordarson/status/1236549305189597189?s=20> 
using Twitter, it went viral. I think I have worked out why. Health 
authorities have been giving us two messages: once you have the virus 
there are no drugs that can kill it or help you get rid of it. But also, 
wash your hands 
<https://www.theguardian.com/society/shortcuts/2020/mar/09/how-to-keep-your-hands-clean-without-getting-dry-skin> 
to stop the virus spreading. This seems odd. You can’t, even for a 
million dollars, get a drug for the coronavirus – but your grandmother’s 
bar of soap kills the virus.

So why does soap work so well on the Sars-CoV-2, the coronavirus and 
indeed most viruses? The short story: because the virus is a 
self-assembled nanoparticle in which the weakest link is the lipid 
(fatty) bilayer. Soap dissolves the fat membrane and the virus falls 
apart like a house of cards and dies – or rather, we should say it 
becomes inactive as viruses aren’t really alive.

The slightly longer story is that most viruses consist of three key 
building blocks: ribonucleic acid (RNA), proteins and lipids. A 
virus-infected cell makes lots of these building blocks, which then 
spontaneously self-assemble to form the virus. Critically, there are no 
strong covalent bonds <https://en.wikipedia.org/wiki/Covalent_bond> 
holding these units together, which means you do not necessarily need 
harsh chemicals to split those units apart. When an infected cell dies, 
all these new viruses escape and go on to infect other cells. Some end 
up also in the airways of lungs.

You can’t, for any price, get a drug for the coronavirus – but your 
grandmother’s bar of soap kills it

When you cough, or especially when you sneeze, tiny droplets from the 
airways can fly up to 10 metres. The larger ones are thought to be the 
main coronavirus carriers and they can go at least two metres.

These tiny droplets end on surfaces and often dry out quickly. But the 
viruses remain active. Human skin is an ideal surface for a virus. It is 
“organic” and the proteins and fatty acids in the dead cells on the 
surface interact with the virus.

When you touch, say, a steel surface with a virus particle on it, it 
will stick to your skin and hence get transferred on to your hands. If 
you then touch your face, especially your eyes, nostrils or mouth, you 
can get infected. And it turns out that most people touch their face 
<https://www.today.com/health/how-coronavirus-spread-how-stop-touching-your-face-prevent-infection-t175189> 
once every two to five minutes.

Washing the virus off with water alone might work. But water is not good 
at competing with the strong, glue-like interactions between the skin 
and the virus. Water isn’t enough.

Soapy water is totally different. Soap contains fat-like substances 
known as amphiphiles, some of which are structurally very similar to the 
lipids in the virus membrane. The soap molecules “compete” with the 
lipids in the virus membrane. This is more or less how soap also removes 
normal dirt from the skin.

The soap not only loosens the “glue” between the virus and the skin but 
also the Velcro-like interactions that hold the proteins, lipids and RNA 
in the virus together.

Alcohol-based products 
<https://www.theguardian.com/world/2020/feb/28/hand-sanitiser-or-hand-washing-which-more-effective-against-coronavirus-covid-19>, 
which pretty much includes all “disinfectant” products, contain a 
high-percentage alcohol solution (typically 60-80% ethanol) and kill 
viruses in a similar fashion. But soap is better because you only need a 
fairly small amount of soapy water, which, with rubbing, covers your 
entire hand easily. Whereas you need to literally soak the virus in 
ethanol for a brief moment, and wipes or rubbing a gel on the hands does 
not guarantee that you soak every corner of the skin on your hands 
effectively enough.

*So, soap is the best, but do please use alcohol-based sanitiser when 
soap is not handy or practical.*

• Palli Thordarson is a professor of chemistry at the University of New 
South Wales, Sydney

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