> the claim is that the virus can mutate, therefore, any particular outcome is equally likely?
No.
Did you actually read the study I linked?
Outcomes that enhance transmissibility are always being selected for. Things like higher viral load in the vaccinated.
That which spreads, spreads.
All things being equal, pathogenicity is neutral and gets down-selected when the pathogenicity conflicts with the ability to spread. But with two different populations, the feedback loop that of down-selective pressure against spread limitations due to pathogenicity may be broken.
If it spreads in one population which requires characteristics that make it lethal in the other population.
Yes. It makes the general argument (not specific to Covid) that is known to any evolutionary biologist: partial selective pressure causes an organism to evolve away from that pressure. It's why we tell people to take their entire course of antibiotics.
It in no way implies that the organism will evolve to do anything else. You wrote this:
> Additionally, we know that leaky vaccines and continued spread may cause greater pathogenicity.
This is NOT supported by evidence, except in the completely silly sense that the virus "may" do anything, if it is allowed to continue existing.
If we partially vaccinate, SARS-CoV2 "may" evolve legs and do a little dance...but it probably won't (...and for that matter, it probably will hit an upper limit on transmissibility as well. But now I am speculating, if only in an evidence-based manner.)
I provided source evidence documenting an example of the mechanism and result of what I'm saying. Get back to me when you can provide a source example case of a virus evolving legs and doing a little dance and then we can consider the probabilities equivalent.
You provided a source showing that a chicken virus escaped selective pressure, in chickens, grown in a lab. Let's not overstate the relevance of your "evidence" to SARS-CoV2 amongst the human population.
But as I said, there's nothing terribly surprising about the idea that pathogens mutate to escape selective pressure. It's right out of biology 101. It would be tremendously surprising if those pathogens became more virulent, which is what you're trying to claim.
No.
Did you actually read the study I linked?
Outcomes that enhance transmissibility are always being selected for. Things like higher viral load in the vaccinated.
That which spreads, spreads.
All things being equal, pathogenicity is neutral and gets down-selected when the pathogenicity conflicts with the ability to spread. But with two different populations, the feedback loop that of down-selective pressure against spread limitations due to pathogenicity may be broken. If it spreads in one population which requires characteristics that make it lethal in the other population.