> The way I understand it is that once a virus has jumped from animals to humans its virulence and danger will decrease continuously.
This is no truer than the quote about "each deadliner than the other". In fact many virii mutate continuously, c.f. the flu shot you need to get every year because there are always new strains.
It seems currently that SARS-CoV-2 is not doing this. But the science is still new and we just don't know.
We are observing mutations, and there’s a number of preprints out there describing mutations along the spike protein. I’m not sure which of the 100 vaccine candidates would continue to work if that were the case, but perhaps it will become like the flu where we need a different vaccine per strain and that sometimes the vaccine only provides partial protection
This is no truer than the quote about "each deadliner than the other". In fact many virii mutate continuously, c.f. the flu shot you need to get every year because there are always new strains.
It seems currently that SARS-CoV-2 is not doing this. But the science is still new and we just don't know.