Post #1374: COVID-19 trend to 12/29/2021. I reject your reality and substitute my own.

Posted on December 30, 2021


This has been yet another morning of looking at the COVID-19 numbers and saying “never seen that before”.

In any case, I’m sure you won’t be able to avoid hearing all the bad news, so let me be brief about that.

The U.S. is now averaging more than 90 new COVID cases per 100,000 population per day.  Here’s how the case counts look, compared to last year:

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 12/30/2021, from”  The NY Times U.S. tracking page may be found at

So far, there’s no hint that this is even slowing down yet in the U.S.

DC remains at roughly 300 new cases / 100K / day.  New York state is now just over 200.  As you can see, the previous state records, set in the last winter wave, were somewhere in the neighborhood of 180 new cases / 100K / day.

That Washington DC number is where I get to the part about rejecting your reality and substituting my own.  In the past, my rule of thumb for estimating the fraction of the population that is contagious has been to multiply the day’s new COVID-19 tests by 12.  That factor of 12 comes from an average of about four days of walking around being contagious, per person.  And an average of three actual cases for every one diagnosed.

Now let me redo that.  Best evidence from CDC seroprevalence studies says that the ratio of actual to diagnosed cases is only about 2 to 1.  And this disease moves so fast, let me assume an average of just three days of being infectious, per infected person.  So in this revised calculation, I would estimate that there are six people walking around, capable of spreading COVID, for every person diagnosed each day.

Which means that, in DC, today, 1.8 percent of the population is walking around, capable of spreading COVID?  Might as well round that up, given the overall accuracy of the estimate.  Two percent of the DC population is walking around right now, capable of spreading COVID?  (Question mark, because I’m looking at that thinking I must have dropped a decimal point or something.  But nope.  6 x 300 / 100,000 = 18/1000 = 1.8%).

If that’s right, your 50/50 group size in DC today is 35 persons.  By that I mean that if you attend an event with 35 people, there’s a 50% chance that somebody in that crowd is capable of spreading COVID-19 today.

I just can’t quite get my head around that.  Anybody who was following along knew there were going to be a lot of cases of Omicron.  I don’t think anybody anticipated quite that many.

Some artifacts?

If I zoom in on just the most recent period, it sure looks like this last couple of days reflect some sort of reporting artifact.  There are a whole lot of states that went from mild increase to nearly vertical, all on the same day.

Here’s the U.S.  Note how nicely coordinated all the ends of the curves appear to be.

Here’s the U.S. South Central region.  Sure, I expect cases to increase.  I don’t expect them to explode simultaneously across all the states in that region.

So, something looks a bit off.  In the past, when I saw that level of coordination across far-flung states, it was due to some sort of reporting artifact.  I can’t, for the life of me, figure out what that would be in this case.  Every state in the U.S. South Central region shifted into extremely rapid new case growth, on the exact same day?  If that’s not some sort of reporting artifact, all I can say is, I’ve never seen that before.


Things are moving so fast that it’s hard to get a grip on hospitalization rates.  They are going up, owing to the huge volume of new cases.  But for the U.S. as a whole, they are still well below where they were at the peak of last year’s winter wave.

Let me just pop in one graph from the CDC COVID data tracker.  As of December 27, we had about the same rate of daily new cases as we had at the peak of the 2020 winter wave.  But only about half the rate of new hospitalizations.

As Omicron continues to displace Delta, the case hospitalization rate should fall.  My point is that in most parts of the country, we still have a ways to go before we overrun the hospital system.

One last interesting observation:  New York state’s COVID-19 case hospitalization rate is now half of what it was three months ago.  If we get enough Omicron cases, sure, we could still overrun the hospital system.  But it’s going to take a lot more cases than it would have taken under the prior variants.

(If you were to go back to (say) the first week of October, New York’s COVID case hospitalization rate was 5.8%.  Now, as of 12/28/2021,New York State was reporting about 5.5 new COVID-19 admissions per 100,000 population, seven-day moving average, versus 190 new cases per 100,000 population, seven day moving average.  Or roughly 2.9 percent.)