Post #1407: COVID-19 trend to 1-19-2022

Posted on January 20, 2022


Daily new COVID-19 cases continue to fall throughout the Northeast region, and are falling particularly rapidly in the NY/NJ area.  By contrast, case counts continue to rise through much of the Midwest, South Central, and Mountain regions.

The result is that the U.S. average new case count continues to decline.  For the past seven days, case counts are down about 3 percent on average.

Source:  Map courtesy of  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 1/20/2022, from”  The NY Times U.S. tracking page may be found at

At some level, there ain’t but so many ways that one can say “there are a lot of new cases”.  Next, I’m trying to put the situation into perspective by showing all states at once.

First, here’s the entire pandemic, going back to April 2020.  The entire chart has to be rescaled, compared to prior versions, to fit the Omicron wave on.  I think the clear conclusion is that there are a lot of new cases.

Second, here’s just the 2021/2022 winter wave, starting on 10/25/2021.  Note that I clipped off the top of the curve for Rhode Island.  Aside from noting that there are a lot of new cases, enough states appear to have peaked that we’re starting to see an arch shape forming, consistent with the peak in the U.S. average rate.

What else is there to say?  We have reached a peak, but there are still a lot of new cases out there.

Impact of school re-opening.

I suppose the only other thing worth looking for is any impact of school re-opening.  In places where kids went back to school immediate after Jan 1, there has been enough time that any resulting new infections should be entering the reported data now.  As I have noted in the past, there’s no timely U.S. dataset that shows U.S. daily new COVID-19 cases by age.  So for questions about the shift in ages, I tend to rely on data from Virginia, where the state is middle-of-the-road and the quality of the data appears to be excellent.

And, where I expected to see exactly nothing — because that’s what I’ve seen so far, for all COVID back-to-school impacts — this time, there’s an uptick.  This, after more than two months of rock-solid stability, during the entire U.S. winter wave.

Source:  Calculated from Virginia Department of Health, cases by age group, file through 1/19/2022, data used through 1/18/2022.

I suppose that merits further investigation, given that potential for Omicron transmission in Virginia schools is something of a hot topic right now (Post #1404).

I’ll put it on my to-do list, but it’s an inherently weak situation to try to analyze.  It’s a poor “natural experiment”, because you more-or-less have a pre-post comparison over time, with no control group.

Maybe the only saving grace, analytically, is that snow delayed start of school in some areas.  For example, Fairfax County Public Schools went back to in-person classes a week late.  It should be too soon for cases picked up in in-person classes to be appearing in the data.

Yeah, well, maybe that’s significant, maybe that’s not.  For Fairfax in isolation, it’s not as if that number was stable in the first place.  I’m not sure I’ll ever be able to tell whether there is a return-to-school effect.  I’ll take a deeper dive into this for tomorrow.

Maybe I shouldn’t be so surprised to think that there might be an effect.  With the switch from Delta to Omicron, we’re now dealing with a disease that is as contagious as the worst childhood diseases.  As contagious as measles or chicken pox.  But without the extremely effective vaccines that suppress those diseases in the pediatric population.  (The standards two-shot vaccine regimen is estimated to be 30% to 40% effective against Omicron — that was the last research I read).  Nor does infection with one of the prior strains confer much in the way of immunity.

(None of which, of course, was mentioned in our Governor’s Executive Order 2, which attempts to ban any effective mask mandates in Virginia K-12 schools.)

The upshot is that the school situation under Omicron really is materially different from what it was under Delta.  Far more infectious, far less immunity to it in the population.  Only a fool — or the Governor of Virginia — would deny the potential for higher in-school transmission rates with Omicron than occurred under Delta.

But it’s too soon to conclude anything yet.  All I can say is that I’ll take a closer look.