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Given that the majority of biologists do not currently consider viruses to be alive, a virus can never die. It can, however, get destroyed by long exposures to soapy water, alcohol, and apparently certain frequencies of UV light.

Why is an individual SARS-CoV2 virion not infectious forever? Or is it?

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    $\begingroup$ Would it help to think a little differently? Rubber bands (for example) aren’t alive either, but there are several ways they can be destroyed, including physically pulling them apart or just by having them exposed to air enough. Viruses are the same, conceptually. $\endgroup$ – Laurel Apr 22 '20 at 13:49
  • $\begingroup$ @Laurel Yes, that does help! So is it simply that being exposed to air very slowly destroys SARS-CoV2 (so slow, in fact, that it takes many days)? $\endgroup$ – RockPaperLz- Mask it or Casket Apr 22 '20 at 14:11
  • $\begingroup$ @RockPaperLizard Probably best to think of it more like something like radioactive decay... Individual viruses may be destroyed immediately, or only after a long time. You're waiting for some sort of chemical reaction to occur that is sufficient to make each individual virion no longer capable of infecting. When people talk about the virus staying on some surface for 72 hours, they have given some % reduction in the concentration that they are waiting for. Almost all of the virions are inactivated well before the 72 hour marker, just not enough to consider them effectively gone. $\endgroup$ – Bryan Krause♦ Apr 22 '20 at 17:00
  • $\begingroup$ @BryanKrause Thanks Bryan. Your comment helps as well. When you write "may be destroyed immediately", are you referring to environmental reactions, similar to the ones that take longer to destroy an individual virion? $\endgroup$ – RockPaperLz- Mask it or Casket Apr 24 '20 at 6:36
  • $\begingroup$ Think of it like "x% of viruses inactivated each minute", starting from a very large number. Depending on what "x" is, it may take a long time to reach something like 0.0000001% of the initial virus concentration where you might say "it's basically all inactive". $\endgroup$ – Bryan Krause♦ Apr 24 '20 at 14:19
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Would it help to think a little differently? Rubber bands (for example) aren’t alive either, but there are several ways they can be destroyed, including physically pulling them apart or just by having them exposed to air enough. Viruses are the same, conceptually.

Soap works in part by dissolving the layer of fat that keeps the virus together. It also ends up surrounding dirt so that it doesn’t stick to your skin and can be washed away with water. (These mechanisms take some time to work so that’s why people are recommended to wash their hands for 20+ seconds.)

As for when a virus is just on a surface, logically we know that how long a virus remains viable depends on both the air and the surface because the science reports different numbers depending on what the humidity is and what the surface is like. One helpful source notes:

Similar molecules appear to interact more strongly with each other than dissimilar ones. Wood, fabric and skin interact fairly strongly with viruses.

Contrast this with steel, porcelain and at least some plastics, such as Teflon. The surface structure also matters. The flatter the surface, the less the virus will “stick” to the surface. Rougher surfaces can actually pull the virus apart.

The surface of fibers or wood, for instance, can form a lot of hydrogen bonds with the virus.

In contrast, steel, porcelain or Teflon do not form much of a hydrogen bond with the virus. So the virus is not strongly bound to those surfaces and is quite stable.

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  • $\begingroup$ Thanks Laurel. So if wood, for example, forms a hydrogen bond with the virion, it has the potential to destroy it in the process? And conversely steel has no such potential since it does not bond with the virion? $\endgroup$ – RockPaperLz- Mask it or Casket Apr 24 '20 at 6:40
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Viruses are made of nucleic acid (DNA or RNA), a few proteins and often lipids (like Corona viruses). they are not alive as they cannot reproduce without host cells but they are delicate and when they lose the ability to reproduce with exposure to the host, the virus is just completely dead...

Its possible to maintain viruses possibly forever by preserving them and freezing them. Just like reproducing - they can't live for prolonged time without help... in this case a human lab tech.

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