Post #1213: COVID-19: Oh ****.

Posted on August 15, 2021


Those of you who follow this blog know that I tend to be a little bit ahead of the curve on the topic of COVID-19.  In a good way.  Please bear that in mind as you read this.

In my past few posts I have been casually mentioning this year’s winter wave of COVID-19.  But I hadn’t really thought about it.  I mean, seriously, it’s August, we just got through a week of temperatures in the 90’s F.  Who in their right mind is thinking about winter?

But in yesterday’s post, I cemented my own thinking about the current (Delta) wave.  Based on what appears to be the duration in the states where it hit earliest, all lines of evidence point to seeing the Delta wave peak some time in early September.

So, for me, it’s time to start thinking past this wave.

Pop quiz:  When did last year’s winter wave start?

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 8/11/2021, from”  The NY Times U.S. tracking page may be found at

If you said “early September”, you get full marks.  But if you said “oh @@@@”, you get full marks plus a bonus point.

And so, all this happy talk about a peak of the Delta wave might just turn out to be just that — talk.  It might not go away at all.  It might just move north and become this year’s winter wave.

What’s different this year?  Look above.  Last year’s summer wave peaked in July.  Just about two months before the current Delta wave is likely to peak.  And so, last year, there were distinct summer and winter waves.  This year, if I had to guess, I’d guess they’re going to merge.

Why I think we’ll have a winter wave this year.

I mean, aside from the fact that we had one last year.  As did most of the rest of the temperate-climate Northern Hemisphere.  And the fact that many airborne viral diseases, e.g., flu, are known to spread during the winter in temperate climates.  And that most other coronaviruses have their peak spread in the wintertime.  (Documented in Post #894).

But aside from that, why do I think there’s going to be a winter wave?  And why  do I think it’ll hit the north (particularly the dry-winter Midwest) hardest?

Mostly, I think that for the same reason that I think the summer waves hit the South:  Indoor humidity.  Or, more properly, the lack thereof.

I wrote a little treatise on this, last year, in Post #894, Why is flu seasonal?  Humidity and COVID-19 spread, final version, posted 11/18/2020.  A rougher version of the same ideas is in Post #879.

In Post #895, I put my money where my mouth is and described my humidifier of choice.  I own two of them.  I ran them continuously last winter.  I plan to do the same this winter. And I bought a humidifier for my daughter’s dorm suite, to boot.

It’s not a secret that relative humidity matters for transmission of viral diseases.  Here’s some sound medical advice on keeping your indoor humidity between 40% and 60%:

Source:  That well-known font of medical knowledge, the American Society of Heating, Refrigerating and Air-Conditioning Engineers.  This is from the 2016 ASHRAE Handbook—HVAC Systems and Equipment (SI), Chapter 22:  Humidifiers.

Last year, I put it this way:  Poor COVID-19 hygiene and dry indoor air is a recipe for spread of disease.  This year, I’ll have to add low population immunity to that, in the form of vaccination or prior infection.  And so, this year, it’s more like:

Dry air + poor COVID-19 hygiene + low vaccination (or prior infection) rate = high peak for this winter’s wave.

Is there a lesson here?  Yes.  Don’t get vaccinated for the Delta wave.  It’s too late for that.  Get vaccinated in preparation for the 2021-2022 winter wave.

Two maps and I’m done for the day.

I imagine I’ve done my bit to darken your day.  I surely have darkened my own.

They say that history doesn’t repeat itself, but it rhymes.  Let me finish this by showing the individual state peaks of last year’s summer wave, and winter wave.  Again, brought to you by the good people at, who make it a snap to generate choropleth maps.  Note that the scales are different, but the point is the same:  Darker is worse.

First map is the peak rates of the 2020 summer wave.

Map courtesy of   Data source cited above.

Second map is the peak rates of the 2020-2021 winter wave.

Map courtesy of   Data source cited above.