Percy writes:
The last thing a respiratory virus wants to do is kill the host. A host that's no longer breathing is no longer seeding the air with virus spawn. So lethality is selected against. A host that is too sick to get out and about among other people is not very useful to the virus. Shut-aways or hospitalized people keep the virus from spreading. So making the host too sick is also selected against.
What a respiratory virus wants most is high transmissibility combined with minimal impact on the host. A highly infected but completely functioning host is the ideal. The best host is probably one who enjoys running in crowded subways. High transmissibility and minimal severity of illness are the selection pressures on covid variants. The most transmissible variant will have a strong tendency to displace all others. If it also causes the least severe illness then that would be the ideal outcome, both for the virus and for us.
We don't yet know the severity of illness caused by the new variants, but if selection pressures can dominate over random outcomes (not guaranteed) then there is reason for hope.
I also have high hopes that Covid will become domesticated if it circulates in the human population. What still concerns me is Covid hiding out in a non-human host for a while and then hopping back to humans. This could have been how we got the Omicron variant to begin with, although I think that hypothesis has fallen out of favor as of late. Whatever happened with Omicron, it was hiding out somewhere for a while and the jump in S gene mutations was a bit worrying.
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