Last estimate I heard was that 10% of US cases were of this variant. But that percentage is highly location-dependent and will grow over time.

The existing vaccines are very effective against this mutation. So for vaccinated people it's not anything to worry about. The problem is, vaccinated people CAN get mild infections, and can likely transmit it to others, who might be unvaccinated.

Our high vaccination rate is likely slowing the growth of the delta variant, but it's only a matter of time until it takes over here as well. This is evolution by natural selection (the thing that republicans were busy banning in schools before they got to work on critical race theory).

And when it becomes widespread, dangerous cases might explode again in unvaccinated populations. The thing that worries me is that vaccination rates correlate with politics (thankyou president whatsisname), and politics correlates with geography. So rural areas, where vaccination rates are very low and safety protocols are rarely observed, might have nasty outbreaks on the way.

Then again, rural areas are less densely populated, so infections can't spread as far. That's one reason we haven't seen as much covid as a lot of people expected in those rural areas so far. Whether they're still below critical density for the delta variant is something we'll only know in time.

Similarly, in cities, where vaccination rates are thankfully much higher, we still have double-digit percentages of the population who are unvaccinated. Whether those people are at major risk will depend on those vaccination rates and also on how effectively this variant spreads via vaccinated carriers. Again, we probably won't know what to expect until it happens. Anyone who interacts closely with unvaccinated people should probably go back to wearing a mask around them.