[PLUG-TALK] Virus robustness Re: Online produce

[Keith Lofstrom]

On Wed, Mar 18, 2020 at 11:04:18AM -0700, John Jason Jordan wrote:
> Clearly COVID-19 can survive and reproduce inside a human body, but
> once it's outside its host, what does it need to survive? Moisture?
> Temperature range? If my car is left outside overnight and the
> temperature drops to below freezing, can I assume that any COVID-19 on
> it is dead by the following morning? What about putting food in my
> refrigerator? And how long can it survive in these various
> environments?

Viruses do not metabolize, they are tiny armored packets
of genetic material with penetrators on the outside. 
They are not "alive" in the usual sense, any more than a 
fragmented cell (or a sword) is alive.  

Computer malware is called a virus because it behaves in a
similar way; it needs the machinery of a host (a computer
operated by a fallible human) to propagate.

Thermal energy will eventually mutate or damage a virus.
99.999% of the mutations fail, most are "neutral", but
some win the genetic lottery and get a whole new species
to inhabit, become more dangerous, or more easily spread.

COVID-19 is an RNA virus, and RNA is less stable than DNA.
It merely needs to get inside the cell (not the nucleus)
to start reproducing, using the cell's machinery protein
production machinery.  Most of the time a virus becomes
non-functional when it mutates, but occasionally a mutated
virus becomes better adapted to a new host.  For example,
bat coronavirus mutates, and a single one of the mutants
accidentally became human specific COVID-19.  It is still
mutating.

COVID-19's long incubation time makes its victims
infectious long before they become symptomatic.  That is
near-optimum for infecting sapients.  Evolution selects 
variants of COVID-19 for maximum spread; lethality in old
people is an unimportant side issue to that evolution,
though it exposes a lot of young medical staff to it.

We're still learning about COVID-19, and in the flurry of
new papers there is a lot of brilliant insight and a lot
of utter bilge.  We don't know which is which yet.

--------

Some chemical reaction rates double with every 10C increase
in temperature.  I'd expect most COVID-19 virus particles to
survive 10 days on an undisturbed hard surface;  if there are
a million of them, I'd expect a "lucky few" to last two months.
Those few might not be lucky enough to infect somone, but the
"lucky many" early on will have a much higher chance.

Freezing definitely WILL NOT kill a virus.  In fact a virus
will probably last centuries at liquid nitrogen temperatures.
Chemical damage from soaps and disinfectants will damage a
virus particle, but then you must do a very good rinse or
the chemicals will damage you.

--------

I wrote about produce, lettuce handled by multiple customers
in a grocery store in particular.  I found this 2012 paper
on Pubmed:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4980993/

"Stability of bovine coronavirus on lettuce surfaces under
household refrigeration conditions"

Summary:  Still there after a month.  A coronavirus lasts
longer than the lettuce does.

Conclusion: Don't eat lettuce that was handled without
gloves, especially by J. Random Customer.

Keith

-- 
Keith Lofstrom          keithl at keithl.com