Tell the Black Plague its strategy of killing 30% of is suboptimal. Or to the species driven to extinction by a disease. “Inanimate object, that was suboptimal to your existence!”
A random mutation that causes the virus to be more mild would cause people to rationally take fewer precautions against it. Then it gets to spread more, which is evolutionarily advantageous to the virus, but it doesn't kill as many people, which is advantageous to humans.
Note that there are a ton of viruses people get infected by on a regular basis that don't even have symptoms. Those viruses "spread like the plague" but because they're not the plague, nobody cares.
this occurs when a host is coinfected with two or more viral strands of differing origin. most often virus of close familial lineage do this, but that isnt exclusive.
the mechanism is molecular promiscuity during replication, there is a jump from one strand to another in proximity, thus recombining.
cocirculation is required for this to occur, high frequency of co infection is required for recombinant mutants to occur with predictive certainty.
like the gatekeeper and the keymaster, we should avoid allowing delta, and omicron to contact each other, and surveil the sequences closely.