The coronavirus is a self-assembled nanoparticle in which the weakest link is the lipid (fatty) bilayer (see the figure).
The viruses tend to be made up of three things:
- A nucleic acid genome (their genetic material: DNA or RNA).
- Protein, which encases the nucleic acid and aids viral replication inside a host body.
- A fatty outer layer of lipids.
The junctions between these three components provide the structure of the virus, but these junctions are weak - there are no covalent bonds in action that provide a more stable structure. Instead, viral self-assembly is based on weak "non-covalent" interactions between proteins, RNA, and lipids. Together they act like a Velcro, so it's very difficult to disperse the self-assembled viral particle.
But it is possible to break the particle with soap, which is particularly good at dissolving the lipid layer surrounding the virus. It also inhibits all these other weak links within the virus. Once this happens, the virus effectively collapses. Washing with water alone is much less likely to displace the virus from the surface of the skin. The soap contains fats called amphiphiles, which are similar to the lipids found on the membrane of the virus. When the soap comes into contact with these fats, it binds to them and causes them to detach from the virus. It also causes the virus to detach from the skin.
You do have to be vigorous with your hand-washing though. That’s why the advice is that hands should be washed thoroughly for at least 20 seconds. Other substances are also effective, such as alcohol-based gels. Those with high alcohol content (usually 60% to 80%) will also dissolve the virus, but the antibacterial properties of such products will have no effect on viruses.
