[fallingfrog]

Do you know this for a fact or is that just a plausible idea you came up with? It sounds plausible enough but it also sounds plausible that if symptoms were delayed even more or failed to show up at all it might be transmissible for longer, meaning that that there would still be selective pressure towards less virulent strains.

[rolph]

this is fact, this is evolution. when reproduction occurs this is success, this is fitness to reproduce. if a host is killed, or inconveinienced enough to lay ill and not contact others, that is a selective factor that favours reduction of morbidity. in the case of coronavirus reproduction and transmission occurs before morbidity occurs in the index host. there is no selective pressure to become less virulent. there is selective pressure to change host, to evade recognition by the immune system.