Saturday, September 25, 2021

[igsptmew] COVID-19 "what if?"

previously, summary of Randall Munroe's "what if?" book chapter on this question: "If everyone on the planet stayed away from each other for a couple of weeks, wouldn't the common cold be wiped out?"  (tl;dr: no.)

we apply some ideas from that chapter to COVID-19.

open question: how large is the group of people who can harbor the COVID-19 virus for very long periods of time?  i worry that it might not just be people who are generally immunocompromised -- those people are (probably) easily identified and can be isolated (and are probably glad to be isolated, if they aren't already) -- but might also include many "normal" people whose immune systems are weak only to respiratory infections, or who despite a COVID-19 infection persisting for a long time, might not be very inconvenienced by it.  isolating a large group of people, perhaps including many normal-ish people against their will, so that they do not seed new outbreaks will require significant abrogation of their civil rights.

but given that some countries seem to have contained COVID-19 without vaccines, perhaps isolating certain people is not so bad.

in contrast to human rhinovirus, SARS-CoV-2 (the virus that causes COVID-19 in humans) can infect other animals (e.g., mink), so wild animals can be a permanent reservoir of the virus (and new mutations), impossible to wipe out.  (perhaps not impossible, cynically: we humans are good at extincting other species.)  although domesticated animals can also be a reservoir, wiping them out is feasible, though maybe politically difficult.  mink have already been "culled".  in the past, livestock were killed (with political difficulty) to stop Nipah virus outbreaks, though wild bats remain a permanent reservoir.

open questions: how much does SARS-CoV-2 infect other animals, how much do the animals then infect each other, and then how much do animals infect humans back (perhaps in mutated form)?

cnatan-na-gall illustrates the controversial "herd immunity" (not referred to as such in the book) approach to dealing with an infectious disease epidemic actually working.

"herd immunity" can refer to two different things, so we qualify them as follows:

controversial herd immunity:
exemplified by cnatan-na-gall.  disease dies out after natural spread to most of the population.  Munroe calls this viral extinction and viral clearing, though the latter term seems mainly to mean the clearing of virus inside one person, not a population.
vaccine herd immunity:
disease stops spreading due to most people being vaccinated.

open question: under what conditions (beyond cnatan-na-gall) does the controversial herd immunity approach work?  can it work for COVID-19?

the controversial herd immunity approach for COVID-19 (notably advocated by Trump) has been deeply politically controversial, with opponents decrying it as "not science", and "it has never worked for any disease ever".  cnatan-na-gall is an example of it being science, and it having worked.  unfortunately, the error of labeling the approach "not science" has a major consequence: it breaks trust.  every single claim of anything else having been dismissed as "not science" now has to be reexamined: was it really "not science", or was "science" just being used as a deceptive political ploy to sway gullible minds?  accusations of the latter are frequently made by critics of the policies supported by "science" and proponents of policies criticized as "not science".  cnatan-na-gall shows that their accusations have merit: the can of worms has been opened.

with the can of worms opened, opponents of policies combatting climate change unfortunately gain political power, because they can point to the above as an instance of "science" being used deceptively, as a political ploy.

we should not have criticized the controversial herd immunity approach to COVID-19 as "not science".  we should have criticized it as "the costs outweigh the benefits" or "it won't work because (this is a wild guess) the virus mutates too quickly in large populations".  (the latter, if true, implies that vaccines will also not be effective.)

open questions: if some vaccine does work to wipe out SARS-CoV-2 (this is a big if), does that mean controversial herd immunity also would have worked?  forget about weighing their costs for the moment.  do vaccines generically have some additional power that controversial herd immunity does not?  ultimately both train the immune system to detect and reject the virus.

if we had really wanted to get most of the world's population infected with COVID-19 as quickly as possible (perhaps so quickly as to head off mutation), we probably could have done it quicker than vaccine development and rollout.  (of course, the costs of lives lost and maimed would have been extremely high, though to quantify that cost for comparison with the cost of vaccine development and rollout requires putting a value on human life.)  the disease automatically spreads itself.  it's interesting how the virus and cryogenic transport of the vaccine do exactly the same thing, transport RNA, one by natural means and one by artificial means, the latter requiring much more technological infrastructure.

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