Links? Mutations occur in infected hosts, which vaccines were limiting.

Even with Omicron, a report that hit HN a day or two ago indicated a 5x difference in infection rates created by vaccines.

I think parent post is implying that the situation with Omicron is much more complicated.

Alpha, Delta variants, sure, we can see them evolving pretty much site by site to become the things that they are. There are enough uploaded sequences you can basically watch it happening.

I suppose you can blame the unvaxxed for increasing the probability of such variants.

But Omicron turns up with a freakishly weird number of synonymous vs non-synonymous mutations in the spike, lots of adaptions for immune evasion and... it's rooted in the phylogenetic tree back in 2020? So it just evolved in secret for 18 months, becoming incredibly transmissible while managing not to infect a single person who got sequenced? Bear in mind that is conservatively 100 generations, usually. It's super weird. Whatever process produced Omicron, it was radically different than regular infection and transmission.

This is not something we could reasonably have expected from say, increased infections due to some people not being vaccinated.

In fact all the variants from "regular" transmission over the course of this pandemic - the result of hundreds of millions of infections - are being out-competed by this bolt from the blue.