Post #1222: Looking beyond the peak of the U.S. fifth (Delta) wave.

Posted on August 25, 2021


In this post, we pry our eyes off the peak of the Delta wave — off the train wrecks occurring in Florida, Louisiana, and Mississippi — and purposefully look elsewhere.  There are two main questions:  Which states are the rising hotspots, and when/where should we expect the U.S. winter wave?


Part 1:  Rising hotspots.

It’s not obvious how to define this category.  I’m putting FL, LA, MS aside.  What I’m looking for is the next set of states that will stress out their hospital systems over a large geographic area.   That seems to occur pretty consistently when new cases per 100K per day exceeds a value of about 100.

Accordingly, a state might be on the watch list either because they have a high level of cases now, or because they have a more modest level of cases, but a high current growth rate.

For this exercise, I’ve tagged all the states that I would project to exceed that 100 / 100K / day mark within the next two weeks, if they maintain their current seven-day rate of increase.  In short, these are the states where you’d expect a hospital crisis in the next couple of weeks if they stick to their current trend.

Data source for these and other graphs of new case counts:  Calculated from The New York Times. (2021). Coronavirus (Covid-19) Data in the United States. Retrieved 8/25/2021, from”  The NY Times U.S. tracking page may be found at

Map (below) courtesy of


Not terribly interesting in and of itself.  It’s an arbitrary cutoff, and and arbitary projection.  Let me pull those apart a bit.

The cluster at the bottom right of the map is clearly just an extension of the current wave.  A few more Gulf states, a few more South/South-Central states. I would characterize that as “no surprises there”.

Geographically, the oddity here seems to be the adjacent states of Wyoming and South Dakota. (Throughout the pandemic, Alaska has largely taken its own independent course.)


The oddity is reinforced by the complete absence of a summer 2020 wave in those states.  If I stick with the story that “the Delta wave is just the 2020 summer wave, but worse”, those two states break the rules.

A second oddity is that both South Dakota and Wyoming were leaders in the U.S. 2020 winter wave.  Now, I know what you’re thinking.  It’s not winter yet.  Today it’s going to in the 90’s F here in Virginia.  It’s way to soon to be thinking about the winter wave.

But just look back to last year, see when those two states began their rise for the 2020 winter wave.  It was, in fact, end-of-August, early-September.  Those are the callouts on the chart above.

Not quite sure what to make of that, but it’s interesting enough to flag it.  Three states break my “Delta is last year’s summer wave” rule.  Two are geographically isolated from the rest, but are next door neighbors.  Those were two of the three states (along with ND) that led the winter wave.  And they started their upturn for the winter wave right about this time last year.

It’s a bit of a stretch to call that the start of the 2021 winter wave.  For the next couple of weeks, it’s a pretty good bet that we’ll be seeing the same crisis headlines repeated, just plugging in different state names.  Fill-in-the-blank has run out of ICU beds.  Feds step in to set up temporary hospitals in fill-in-the-blank.  And so on.

But as we have our attention glued to the current crises, it’s worth keeping an eye on Wyoming and South Dakota.  They are breaking the rules for the U.S.  summer wave.  But the are not breaking the rules the start of the U.S. winter wave.

Part 2:  Maps of history and of predisposing factors, painting a bullseye on Wyoming.

Here, I just figured I’d repeat what the last winter wave looked like, and geographically cross-reference that to two current risk factors:  Lack of vaccination, and lack of COVID-19 hygiene (in the form of mask use).

Lack of vaccination doesn’t tell the whole story, because people can and do acquire immunity via prior infection.  But it’s the only hard number you can get, and I’m frankly tired of trying to take a stab at the number of COVID-19 cases that occurred but were not reported.

Here goes.

All of these maps below are courtesy of  If you’re trying to create a map like this, there’s no easier place to do it.  Cut and paste the data from your state-level spreadsheet to their website, and out pops a nice map.

Last year’s winter wave (this repeats a chart I put up about a week ago).  As you can see from the above, the U.S. winter wave seemed to center mostly on the upper Midwest and Mountain states.

If we look at current levels of mask-wearing, the map is interesting for two reasons.   First, the epicenter of the 2020 winter wave corresponds to the epicenter of current lack of mask-wearing.  That's the top red circle.  But, interestingly, learning has take place in the South.  The South masked up a bit, in response to the Delta wave.  If you were to look at that mask-wearing map from a couple of months ago, it would have looked quite different.

Source:  Carnegie-Mellon COVID delphi project.

Source:  Carnegie-Mellon COVID delphi project.

Finally, I'm overlaying the vaccination rate.   People talk about the unvaccinated South, and that's true.  But Wyoming stands out nearly as starkly as Mississippi and Alabama.

When I put all that together, I see a bullseye on Wyoming, once this current Delta wave peaks.  They had one of the earliest and worst outbreaks last winter.  Rates are climbing there now, and it's just about the same time their wintertime wave started last year.  They have a low rate of mask use, and they are among the worst U.S. states for vaccination rate.

Doesn't seem like much of a stretch to say that they are are pretty high risk right now.  I wonder if they'll do anything proactively to address that?