Post #1047: New cases down 77% from peak. Will the U.S. flunk the marshmallow test?

Posted on March 8, 2021


The national picture remains good. Daily new COVID-19 cases are just 23% of the peak level, and new cases are falling about 12% per week.

How much longer that will last is not yet known.

You will see experts pointing to the recent upswing in new cases in continental Europe.  They will claim that this means fourth wave in the U.S. is inevitable.

That’s not logically correct, as this post explains.  Mostly, we have a lot more immunity to COVID-19 than the typical European country does.  So the situations are not comparable.

That doesn’t mean we’re not going to have a fourth wave.  It just means that it’s still too soon to tell.

Give it a couple of weeks, and we should know one way or the other.

You’d think, in the context of a year-long pandemic, a couple more weeks of COVID-19 hygiene wouldn’t be a big deal. It’s just a question of whether the overwhelming majority of the U.S. can pass the marshmallow test.

As of 3/7/2021


But there’s no denying that more-infectious variants are spreading.  Not only are we doing nothing (e.g., not having a national policy to promote use of N95 masks), states are rolling back restrictions.

New York (has its own more-infectious variant):  NY / NY / RI new cases have stopped falling:

Florida (highest incidence of U.K. variant in the U.S.):  Too soon to tell.


California:  (California has its own COVID-19 variant):  Still falling at a steady rate.


I won’t even bother to comment on recent changes by (e.g.) Texas.  Having a Republican governor do something foolish during the pandemic, and then crow about it, is no longer newsworthy.  That’s just standard operating procedure, has been since the start of the pandemic, and apparently will be right to the bitter end.

Nah, this section is more about misbehavior by the adults in the room.  Really, it’s about the penalties for having cried “wolf” just one time too many.  About playing the fear card so frequently that maybe not enough people will pay attention when there really is a threat.

Here, I’ll focus on the non-existent post-holiday surges. Because we were warned, repeatedly, about that.  And after the fact, when nothing happened, people didn’t bother to take the time to analyze the data to see what actually happened.  Let alone say “oops”.

You were told that a million people a day used air travel over the holidays.  A million!  Oh my gosh!  What you weren’t told is that 0.9M people a day used air travel before and after the holidays. So that there was, in fact, no huge surge of air travel of the holidays (Post #939).  If I hadn’t marked Thanksgiving and Xmas on the chart below, and didn’t provide dates, you’d be hard-pressed to identify where the holidays were.

In fact, the true absurdity is that actual new U.S. COVID-19 infections began to fall sharply just before Christmas So the entire time we were being warned of a post-holiday surge, the reality is that we were experience the collapse of the U.S. COVID third wave.  It just didn’t show up until 1/8/2021 due to all the lags involved — between infection and symptom onset, and so on, until the diagnosed infections data finally get reported by the state health authority (Post #989).

Did we learn from this?  No.  And those who won’t learn from their mistakes are (almost certainly) doomed to repeat them.  Which we duly did, but upped the ante by converting “surge” to “explosion”, to warn against Super Bowl parties.

And when that post-Super-Bowl “explosion” of new cases didn’t occur — again with about 16 days’ lag — was there any followup?  No, of course not.  E.g., was there no explosion because people were dissuaded from having those parties?  Nobody will know, because nobody will follow up, because if we did serious followup, somebody in power would have to admit to having been wrong.  The sum total of reporting on the non-explosion was one article, by one TV station in Tampa (Post #1029).

And now that same long lag between infection and reporting of cases, combined with a population that has heard “wolf” too many times, is setting us up for a possible fourth wave of COVID-19.  With as pretty as the U.S. national picture looks right now, and all the frankly incorrect predictions of “surges” in the past, who in their right mind, in the U.S., would take the warnings about the U.K. variant seriously?

Vaccination, infection, and the herd immunity table updated.

Other than somebody who has spent a lot of time studying the data.

So, as my public service for today, let me just try to get an accurate assessment of the situation, combing two prior analyses.  Because things change.  And the most recent data has two bits of good news.  And, really, it’s a race between population immunity and the greater infectiousness of the U.K. and other COVID-19 variants.

First, regarding vaccinations, we are well ahead of where a simple linear extrapolation would have put us.  As of 3/8/2021, we’re new roughly where we would have been at 4/1/2021 if there had been no acceleration of the pace of vaccinations.  So that’s good news, and requires revising my “herd immunity” table accordingly.

Separately, we have quietly transitioned to having the majority of the vaccinated population being “fully vaccinated”, having gotten both shots.  That wasn’t the case the last time I refreshed this analysis, about a month ago.

And the upshot is that, if we can assume five total infections for every reported infection, right now, the majority of U.S. residents should now be immune to COVID-19.  As shown in the calculation below.  (Counts of vaccinations and infections are from the CDC dashboard.)

You will see supposed experts point to the current “surge” in (continental) Europe and say that such as surge is inevitable in the U.S.  This is logically incorrect.  If fails to account for the brilliant U.S. leadership that resulted in our having vastly more COVID-19 cases per capita than most of continental Europe.  And our much faster rate of vaccination.  And, because of those two factors, continental Europe is in a much more vulnerable position than we are.

Germany, for example, has had about 2.5M diagnosed COVID-19 cases, out of a population of about 80M.  Or, in round numbers, about a third of the number of diagnosed cases that we’ve had, per capita.  In addition, they currently have under 3% of their population fully vaccinated, versus 12% of the U.S. population.  Combined, that leads to much lower overall rates of COVID-19 immunity in continental Europe than in the U.S.

Here’s how the U.S. would look, at those German rates (one-third the number of infections, one-fourth the number of vaccinations).  Maybe 16% of the population would be immune (again assuming five undiagnosed cases for every diagnosed case.  That assumption on the un-diagnosed may be excessive, given Germany’s generally good track record at testing and the efficient ways they went about it (Post #605.)

The only point here is that just because continental Europe is having a surge in cases, that does not necessarily imply that we will.  Or that we won’t.  Our situation is markedly different from the typical country in continental Europe.  In most of Europe, the great majority of the population has no immunity to COVID-19.  In the U.S., that is (probably) no longer  true.

The second thing to keep in mind is how slow the transition to a fourth wave should be.  And how long the lags in the system are.  My original “simple model” was set to run a little fast, and as of 3/3/2021 it was running about four days too fast.  And so, the original prediction that the 4th wave would start in the 3rd week of march needs to be pushed off by about a week.  If the only thing happening were the takeover of the U.K. variant, we’d now expect the declines in new cases to stall out, and begin rising, in the fourth week of March.

Note:  This model is outdated and runs a little bit “too fast”.  See text above.

But this simple model doesn’t account for changes in herd immunity over time.  it just takes the observed rate of transmission and runs with that.

If I project the herd immunity table out to the end of this month, assuming 2M vaccinations per day, and a new-case rate of 15 / 100,000 / day, we should be approaching 60% of the population immune to COVID-19 by April 1.  Surely, at that level, that has to start having some impact.

My point is, there’s nothing certain about a fourth wave.  We may or may not see it. 

For sure, relaxing COVID-19 hygiene under theses circumstances is pretty spectacularly stupid.  (Everything above assumes that we maintain the same level of hygiene as we did in the past, because that’s the level of hygiene that generated the historical numbers.)  We’ve got maybe a couple of weeks to go before we’ll know whether or not there’s going to be a 4th wave, all other things equal.  As a nation, the remaining adults just have to pass the marshmallow test for the next two weeks.