Earlier quoted context omitted.
There likely is no herd immunity to be had. Omicron infects those with previous delta infections, and there are cases being studied further from South Africa of omicron cases getting reinfections of omicron. I think our best chance is faster vaccine cycles and better targeting of the sequences to impede transmission.
A week or two ago they were saying Omicron might confer Delta immunity. Don't overlook that part.
The mRNA vaccines also seem to confer a significant level of durable cellular immunity against all variants, although they also don't reliably prevent infections.