Post #1184: COVID-19 trend to 7/23/2021: A ray of light.

Posted on July 24, 2021


This was no material change in the trend in new cases today.

New COVID-19 cases increased just over 60% in the past seven days.

Louisiana and Florida are virtually tied for the #1 spot, with 51.6 and 51.7 new COVID-19 cases / 100,000 population / day, respectively.

The U.S. as a whole now stands at 15.5 new cases / 100K / day.

Accordingly, I’m sticking with my prior predictions for this wave of COVID-19.  This is shaping up to be the worst ever in the U.S.  If current growth in new cases persists, Louisiana will hit its all-time record for daily new COVID-19 cases next week.  Florida will do so the week afterward.  If nothing changes, this is going to get ugly, soon.

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 7/24/2021, from”  The NY Times U.S. tracking page may be found at

A ray of light from Missouri?

A ray of light does not necessarily mean a ray of hope.

I see one tiny little ray of light in the data.  This wave started in Missouri, and nine weeks after cases began to rise there, if you squint your eyes, it’s starting to look like Missouri’s curve may have passed an inflection point.  See how the end of the curve is starting to look concave downward, like the top of a hill?  Missouri might be getting close to a peak in new cases per day.

It’s too soon to tell, but it’s well worth keeping an eye on Missouri, and marking the peak when it occurs.

This is worth tracking because prior COVID-19 waves tended to have a fairly uniform duration across the states.  States that started a wave early, finished early.  Those that started late, finished late.

Let me illustrate with the U.S. third (winter) wave.  In the graphs below, the blue line is the curve for the U.S. as a whole.  The first graph shows that the Midwest led on the way up, and on the way down.  The second graph shows that the South Atlantic region lagged on the way up, and lagged on the way down.  In all cases, the duration (width) of the wave was about the same.

To be clear, there’s no fundamental reason that this should be true.  And, for sure, there’s a lot of raggedness to the lines above.  This is merely my crude empirical observation.

If Missouri peaks seven to eight weeks after cases began rising there, that gives us a preliminary estimate for when we would expect the U.S. as a whole to peak.

Lacking any other information, that preliminary estimate is better than anything else we’ve got.  So let’s run with that.

For the Delta wave, U.S. cases really began rising around June 29.  If the overall U.S. wave has the same duration as the Missouri wave, that puts the U.S. peak sometime in the third or fourth week of August.  Perhaps four or five weeks from now.

(Now, in some mythical world where the U.S. COVID-19 response was rational,  other states would have learned from Missouri.  Forewarned, they’d have taken steps, and that would reduce the duration of the wave in other states.  But back in the real world, such foresight appears rare.  I don’t think we can count on the wave being any shorter in the states that were given fair warning than in the states for which we can pretend that they were taken by surprise.)

That’s the good news from Missouri.  Maybe they are seeing the light at the end of the tunnel.  And, based on the observed behavior of prior waves, maybe the Missouri wave, if it is peaking, suggests it might be as little as four weeks before the entire U.S. wave peaks.

The bad news is that if the current rate of growth keeps up for just four more weeks, the daily new case count at the peak of this Delta wave will be 50% higher than it was at the peak of the U.S. third (winter) wave.   

As always, given the lag between infection and the final data reporting, the first two weeks of that are already locked in.  Those infections — — whatever they are — have already occurred.   We’re just waiting for them to be discovered, reported, and worked into the data.

I’m not trying to be a fear-monger.  I’m just using whatever data I can find to do the simple math to put some parameters on this wave.  From where I sit, absent some unprecedented change, this wave is likely to be at least as bad as the U.S. third (Winter) wave.  And there’s non-negligible risk that it may end up being materially worse.

I am well and truly freaked out by this.  The clock is ticking, time is short, and I don’t understand why those in power don’t appear to be as alarmed about this as I am.  When I look at the data, I truly do not understand why our response has been tepid-to-nonexistent so far.

After a year and a half of this, is our game plan still to pretend that this will go away?  Pretend, until the hospitals fill up and we can’t pretend any more?  I’m finally starting to see some hints of the appropriate level of panic in the popular press.  But I’m sure not seeing much of anything in the way of actions to match that by state or federal government.