The last few weeks have seen hand sanitisers go off the shelves, to the extent that there is now a government order to ensure availability and to prevent profiteering. How do these protect you against the novel coronavirus? Alcohol’s function in killing the virus is much the same as that of the common soap, which has emerged the greatest weapon against COVID-19 with the limited availability of sanitisers. Handwashing for 20 seconds at least kills the virus. When using a sanitiser, it should ideally have an alcohol content of 60% or more.
Dr Shobha Broor, former professor of microbiology at AIIMS, explained: “The novel coronavirus has a lipid envelope. Soap being a detergent destroys the envelope. The same is true for alcohol. You see even when the virus comes out through droplets when an infected person coughs, it is still within a cell. Even if it isn’t, it can stay alive in surfaces for some time. It replicates only when within the cell. That is how soap or alcohol attacks the virus.”
The US National Institutes of Health explains the structure of the virus: “Like other coronaviruses, SARS-CoV-2 particles are spherical and have proteins called spikes protruding from their surface. These spikes latch onto human cells, then undergo a structural change that allows the viral membrane to fuse with the cell membrane. The viral genes can then enter the host cell to be copied, producing more viruses. Recent work shows that, like the virus that caused the 2002 SARS outbreak, SARS-CoV-2 spikes bind to receptors on the human cell surface called angiotensin-converting enzyme 2 (ACE2).”
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All of this is held together by a fatty layer, called an envelope. That is the layer that is disrupted when it comes into contact with soap or a hand sanitiser with more than 60% alcohol, as Dr Broor explained. Disruption of the envelope causes the virus to come undone, and kills it.
That is why experts and public health institutes across the world agree that handwashing for at least 20 second is the most failsafe prevention of COVID-19.
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