It seems like an interesting hypothesis but I don’t think it’s particularly likely. I’ve never heard of other viruses becoming well adapted to humans within a single host. Though, I do think that’s the explanation for how several variants evolved (since some of them emerged with a bunch of functional mutations rather than just one or two). I’d be interest to see more research into the evolution of viruses within human hosts, and what degree of change is possible & how this relates to spillover events.
It seems like an interesting hypothesis but I don’t think it’s particularly likely. I’ve never heard of other viruses becoming well adapted to humans within a single host. Though, I do think that’s the explanation for how several variants evolved (since some of them emerged with a bunch of functional mutations rather than just one or two). I’d be interest to see more research into the evolution of viruses within human hosts, and what degree of change is possible & how this relates to spillover events.