Post #1149: COVID-19 trend to 5/20/2021: Now 61% below peak

Posted on May 21, 2021

I apologize to my readers for failing to post lately.  I hope to make it up to both of you by posting more in the next couple of days.

Otherwise, I’m probably going to stop posting as frequently about COVID-19, because there just isn’t much to say at the moment.  As far as most of America is concerned, the pandemic is more-or-less over.

The rate of new COVID-19 cases per day is now 61% below the peak of the U.S. fourth wave.  Every region is seeing weekly percentage declines in the double digits.  The rate of decline seems fairly steady.

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 5/21/2021, from”  The NY Times U.S. tracking page may be found at

What was a chaotic mix of different rates and trends just a few weeks ago is now and orderly “regression toward the mean”.  The trend lines are all funneling down toward a narrow range of levels and trends.

The remaining problem is that while the rates are coming down, COVID-19 isn’t fully going away.  Not in even one state.  I’ve documented a few low-population rural counties that are plausibly COVID-19 free.  But in terms of the overall scope of the pandemic, we’re seeing states achieve low rates, but we not seeing any state actually get the virus out of circulation.  There’s still some air under the right-hand-side of the curve.

With the slowdown in infections, and the slowdown in vaccinations:

Source:  CDC

progress toward achieving herd immunity has slowed and is getting slower.

And so, I guess the next thing to look for is whether the formal advice from CDC to relax mask rules for the vaccinated had any impact on the rate of new infections.  I would guess not, given what I see in this area, which is that mask use pretty much continued as it has been before, maybe just a little sloppier.  In any case, given the lags involved, if there is an uptick as a result of the CDC guidance, that will only show up toward the end of the month.

After that, the next thing to look for will be a repeat of the U.S. second wave, wtih a peak of new cases in hot-climate states in July.  This was plausibly attributed to the large amount of time spent in air-conditioned spaces in those states.

And then we’ll see what the fall brings.  Maybe by that time, we’ll finally get enough people vaccinated to achieve herd immunity.  And maybe not.  Maybe either way, this virus will become a permanent part of the infectious landscape.

Too soon to tell.  But for sure, things are blessedly boring right now.  And that suggests that there’s no need to post obsessively about trends.  Maybe once a week, I’ll check back in and see how the trends are going, from now on.