Post #1193: COVID-19 trend to 7/28/2021

Posted on July 29, 2021


No change in trend.  Currently at 20.7 new cases / 100,000 / day.  New cases are still rising at about 60% per week.

Data source for this and other graphs of new case counts:  Calculated from The New York Times. (2021). Coronavirus (Covid-19) Data in the United States. Retrieved 7/29/2021, from”  The NY Times U.S. tracking page may be found at

There’s still no indication of anything but free-running unconstrained spread in most states.  Below you see all the states on one graph.  I hope that you’ve seen enough of these graphs that you notice the eerie uniformity of the slopes (the growth rates) at the right. 

It’s as if God ran a comb though that tangle of state lines.  And so gave us all the same rate of growth.  In all the time I’ve been looking at these graphs, I’ve never seen something that orderly.  Hence “eerie”, above.

Those lock-step growth rates suggest to me that nobody has done anything effective to slow this down.  (Or, more properly, given the more-than-two-week lag between infection and full reporting, that nobody was doing anything two weeks ago to slow this down.  And so, here we are today.)

The other striking uniformity is the geographic clustering of the states with the highest number of new cases / 100K /day.  Note the labels on the lines above.  There’s a strong presence of U.S. Gulf Coast states (FL, Al, MS, LA).

The geographic clustering extends well beyond the Gulf states.  In the map below, I’ve colored in continental U.S. in tiers, in terms of current COVID-19 new cases per 100K per day.  The Top 10 are red, the next 10  are pink, skipped the middle ten, Next-to-Bottom 10 are light green, and Bottom 10 are deep green.

The Northeast (low) versus Southwest (high) clustering is stark.  I’m not exactly sure what to make of that, but my reaction is that, at least in part, this is a re-run of last year’s summertime wave in hot-climate states.  It’s just amped up by the greater infectiousness of the Delta variant.

We know that it COVID-19 spreads almost exclusively in indoor settings.  There’s good evidence that lower humidity aids in spread of viruses of this sort.  Air conditioning dries out indoor air, and the hotter it is outside, the dryer the relative humidity is inside.  So that would at least make some sense (Post #894, Post #895)).

Source:  American Society of Heating, Refrigerating and Air-Conditioning Engineers, 2016 ASHRAE Handbook—HVAC Systems and Equipment (SI), Chapter 22:  Humidifiers.

But it could be as simple as vaccination rates.  Certainly, if you overlay that map with a map of vaccination rates (from CDC), there’s a lot of correlation.  The contrast of the Northeast (deep green, deep blue) versus the deep South (deep red, pale blue) matches up nicely.  As does New Mexico as the sole exception to high new-case rates at the U.S. southern border.  But elsewhere, the correlation between vaccination and current new-case rates isn’t so great.  Washington is as heavily vaccinated as any state in the U.S., but has a high case load.  I have to wonder if the recent hot weather there — and the need to stay in group air-conditioned shelters — plays a role in that.

Source:  CDC COVID data tracker.

Of course, many factors can affect this, so it’s a fools errand to expect a simple story based on any one contributor.  Surely some of the current pattern of case rates is the luck of the draw, for the states that started this with relatively few Delta variant cases.

An Olympic observation.

My wife and I have been watching quite a bit of the Olympics.  As part of that, we see the at-home celebrations by friends and family of the medalists, as broadcast by the networks.

While that’s fine, those private celebrations illustrate, I think, why we’re seeing what we’re seeing, in the growth rate chart above.

Right now, about 60% of U.S. adults are vaccinated.  I doubt that the friends and relatives of the Olympians who are organizing these Olympics-watching parties check the vaccination status of the invitees.  And so, it’s a fair bet that about 40% of the people at those parties are unvaccinated.

What I have noticed, without exception, is that the Olympics watch parties are un-masked, and that absolutely everyone there is un-masked.  In fact, the only masked watch party I’ve seen was in a school, where presumably that’s a rule instituted by the school.

Just stop for a second and think about that.

The Olympics themselves are a year late.  Why?  Because we’re in the middle of a pandemic, and it was too dangerous to do that last year.   Those parties are being held at remote locations, not in Tokyo.  Why?  Because we’re still in a pandemic, and the organizers didn’t want all those additional people in the stands, risking rapid spread of COVID-19.  The Olympic athletes themselves are scrupulously masked when not actually competing.  E.g., the gymnasts are literally handed a mask as they step off the platform.  Why? Ditto.  Mask use apparently is deemed important given that the virus is still circulating.  Not to mention that only about 83% of our Olympic athletes are vaccinated.

Get it?  The Olympics are a year late.  In-person fan attendance is barred.  The Olympians themselves appear to take every precaution when not actually competing.

Yet the people cheering them on are, to a person, not masked.  As if there was nothing unusual going on.

And nobody says boo about it.  As if that made perfect sense.

I look at that, I look at the growth rates above, I hark back to all the analysis that says that singing and cheering are the best possible way to spread COVID-19. And with all that, even now, nobody thinks that a room packed with loudly cheering adults is any reason to wear a mask.

I know it’s a grumpy-old-man kind of thing, but I can’t help saying, well there’s your problem.