If a virus is not alive, how does it die?

You can’t strictly kill a virus since it is not alive.

Outside living cells, some viruses remain potentially active for thousands of years. A virus recovered from permafrost was able to infect an amoeba. Influenza and corona viruses are thought to stay active for a few hours or days. But the smallpox virus can remain active for years

These days there are many reports about how long the coronavirus remains “alive” or “viable” or “active” on surfaces.  For example this is an abstract of a new paper (yet to be published):


HCoV-19 (SARS-2) has caused >88,000 reported illnesses with a current case-fatality ratio of ~2%. Here, we investigate the stability of viable HCoV-19 on surfaces and in aerosols in comparison with SARS35 CoV-1. Overall, stability is very similar between HCoV-19 and SARS-CoV-1. We found that viable virus could be detected in aerosols up to 3 hours post aerosolization, up to 4 hours on copper, up to 24 hours on cardboard and up to 2-3 days on plastic and stainless steel. HCoV-19 and SARS-CoV-1 exhibited similar half-lives in aerosols, with median estimates around 2.7 hours. Both viruses show relatively long viability on stainless steel and polypropylene compared to copper or cardboard: the median half-life estimate for HCoV-19 is around 13 hours on steel and around 16 hours on polypropylene. Our results indicate that aerosol and fomite transmission of HCoV-19 is plausible, as the virus can remain viable in aerosols for multiple hours and on surfaces up to days.

But then I also read that viruses are not “alive”. They are just a bunch of chemicals, non-bacterial pathogens,  which, by unknown mechanisms, just happen to have

  1. long molecules of DNA or RNA that encode the structure of the proteins by which the virus acts;
  2. a protein coat, the capsid, which surrounds and protects the genetic material; and
  3. in some cases an outside envelope of lipids

Scientific American:





But how then do they die? Clearly there has to be a chemical change. Is it just a case of going from active to inactive as chemistry changes?

And that begs the question as to what that chemical change might be.


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