So, I tweeted this the other day, saying it was critical for understanding the origins and possible vaccine(s) for SARSCoV2. It encompasses two things: phylogeny and range. 
The Asian species form a tight clade, very diverged from the African clade. How diverged? 40M years in pangolin generations is equivalent to ~150M years in human generations, which would put us back roughly at the Monotreme-Placental mammalian split (I know that’s...
...a simplification, since human generation length drops one you go back 3-4M years, but you get my point). Viruses like to specialize in hosts that are similar biologically, so I think this one adapted to Asian species in the past 40M years.
So then I was left wondering, why - if the Indian pangolin is phylogenetically closer to the Sunda pangolin than the species in southern China - is the pandemic taking off in India? Then I remembered the recent genetic data showing SARSCoV2 as a chimera of recombination events...
...between pangolin and horseshoe bat viruses. Makes sense, since they have similar lifestyles - live in caves, nocturnal, eat insects - so they have lived close to each other for millions of years. And where are horseshoe bats found?
Well, there are a lot of species - en.wikipedia.org/wiki/Horseshoe… - but taking two of the major species’ distributions (the others have distributions that are ~similar to these) reveals why there’s probably no herd immunity in India:
So, what does that leave us with? The conclusion that rural southeast Asians, uniquely in the world, seem to have some herd immunity to SARSCoV2. The big question: is there a ‘cowpox’ virus here that can be used for developing a live vaccine, or is the herd immunity due to...
...early childhood exposure to the highly transmissible SARSCoV2 virus itself, at an age when the only symptoms would likely be cold-like, if any. This is what I want to figure out, once the lockdown is lifted and we can set the sample collections and lab work in motion. 🦠🙏🏻
