Post #1180: COVID-19 trend to 7/19/2021

Posted on July 20, 2021

The majority of states reported data for Monday 7/19/2021.  Based on the states that reported data (and an assumption of no change in states that did not), daily new COVID-19 cases rose 51% in the past seven days.

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 7/20/2021, from”  The NY Times U.S. tracking page may be found at

Although today’s seven-day trend is lower than it was at the end of last week, by eye, there’s no inflection point in the curve yet.  I suspect that the seven-day trend number will continue to bounce around quite a bit, due to the choppiness of the data reporting.  As of today, Florida has not yet reported new data, and several other states appear to have reported token (implausibly low) case counts.  My best guess is that some further “catch up” reporting will occur over the next few days and that the seven-day trend number will move back up toward 70 percent or so.

To put this fifth U.S. COVID wave into perspective, below is the national daily-new-cases number for more-or-less the entire pandemic.  (I don’t have the start of the first wave shown because I don’t routinely tabulate the data back that far.)  This is a log-scale graph, so the slope of the line shows the percentage rate of growth.  I’ve sketched in red lines to highlight the growth rates for waves two to five, showing that this is the fastest rate of growth in new cases (steepest red line) so far in this pandemic.

That rapid growth in the U.S. average is occurring not only because cases in individual states are increasing rapidly, but also because this fifth (Delta, Indian variant) wave is hitting all the states at once.  Over the past two weeks, new cases counts have risen in literally all 50 states and the District of Columbia.  No state had stable or falling new case counts.  By contrast, prior waves were piecemeal affairs, starting with a few states and then sometimes spreading to a broader set of areas.  That fact that all the states are contributing ton an increase is one reason that the U.S. average is rising faster now than it has in prior waves.

In absolute terms, the U.S. number is still pretty low.  We have just 11 new cases per 100,000 per day.  But let me update my “simple projections” table, assuming that today’s seven-day rate of growth (51%/week) continues.

I can still say that if today’s rate of growth continues, in two weeks this wave will have been worse than all the prior ones except the third (wintertime) wave.

CDC is still MIA with CYA

In Post #1175, I did an entire song-and-dance about when the CDC should rationally reverse its May 13, 2021 change in guidance.  That’s the date on which CDC said that vaccinated people can go back to their pre-pandemic lifestyles.   No masks needed.

If that May 13, 2021 change in guidance was based on some objective measure of risk of infection, then the CDC should already have reversed that change.  By all but the most simple-minded estimates, the risk of COVID-19 infection is now higher than it was on May 13, 2021.

Today marks the date on which even the most simple-minded rule suggests that the CDC should reverse that May 13, 2021 guidance.  Today’s 11 new cases per 100,000 per day matches the new case rate on May 13, 2021.  Even if we ignore the fact that Delta is more contagious (so risk of infection per existing cases is higher than on May 13), and that cases are rising sharpy (so that, with reporting lags, the actual incidence of new infections in the community is far higher than on May 13, 2021) — even if we ignore that, and stick to the dumbest possible rule, we’ve now reached the point where risk of new infection now exceeds the May 13, 2021 level.

But here’s the bureaucratic angle on this.  The CDC’s recommendations on masking always have a caveat.  It’s a long sentence, the effect of which is, “unless your local government says otherwise”.  So the CDC can hide behind that and say, with a straight face, that nothing about their recommendation prevents states or localities from re-imposing mask mandates.  And, legally, they are quite correct.

Meanwhile, various states and localities look at the CDC recommendation and say that prevents them from imposing of enforcing mask mandates.  Most recently, when Los Angeles re-imposed a mask mandate, the local sheriff  refused to enforce it on the grounds that it was “not backed by science“.  Meaning, that the CDC did not recommend it.

So it’s a classic case of a difference between what they say, and what they hear.

What the CDC literally says is this:

Fully vaccinated people can resume activities without wearing a mask or physically distancing, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance.

What state and local governments hear, willfully or otherwise, is this:

Fully vaccinated people can resume activities without wearing a mask or physically distancing, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance.

And so the CDC has given itself sufficient CYA that it feels it may remain MIA on this issue.  Despite risk of infection being vastly higher now then when they made that change in guidance, they express no interest in reversing that change.

Why does this matter?  In my opinion, the only thing that influences COVID-19 hygiene is social pressure.  If everybody in your community is wearing a mask when in indoor public spaces, that gets the message across that masks are expected. 

And if that’s what it takes, then vaccinated individuals have to wear masks.  Partly for their own protection, but mostly because everybody has to wear masks if mask wearing is to be enforced.  And thanks to inertia at the CDC, states and localities must now (appear to) go against CDC guidance to do that.  They have to require everybody to wear masks, which the popular press immediately writes up as requiring vaccinated individuals to wear masks.  Which is, duly noted, against CDC guidance, kind of.  Except for the phrase in tiny type above.

FWIW, around here, this past week, everybody seems to have masked up again, even though there is no requirement.  At least, that’s my observation, based on not a whole lot of data.  But this is a high-income, high-education, high-achievement part of the country.  (Fairfax County, VA always makes the list of highest-income counties in the U.S.)

That’s just by way of saying that some people will figure out that we need to resume COVID-19 hygiene without the government telling them that.  But it’s not really something you can count on in most places.  Or with most people.

This is why the CDC needs to reverse its guidance, as cited above.  It needs to do that now, almost regardless of what the CDC thinks the science says about risk of harm to vaccinated individuals.  As a matter of public health policy, the only way to get masks on the unvaccinated population that is spreading this variant is to get masks on everybody.   And, despite any bureaucratic weasel-wording, the current CDC mask guidance is preventing that from happening.

Here’s the current disconnect, in one simple graph.  That’s mask use, via the Carnegie-Mellon Covid Delphi project.  Shown on the same page as the seven-day moving average of daily new COVID-19 cases.