gjsman addressed the issue of severity very well, so I'll just comment on tradeoffs. The adaptations that affect severity and those that affect transmissibilit

gjsman addressed the issue of severity very well, so I'll just comment on tradeoffs. The adaptations that affect severity and those that affect transmissibility generally seem to be different. These are two axes on which a new variant can very in either way. The most successful new variants will tend to be highly transmissible (for obvious reasons) but also tend to be lower severity for the reasons gjsman gave in a sibling comment. That's only a tendency though, evolution will throw up variants on all sorts of different points on the transmissibility and severity scales and may the most successful virus win. Yes high severity variants will tend to kill off their victims sooner, but if also highly infectious that might overcome that effect. In any case killing off victims still leaves a trail of devastation. It can take a while for all of this to play out.