Post #1025: Trends, reporting artifact from winter storm

Posted on February 23, 2021

Several states show what appears to be a rebound in new case reporting following last week’s cold weather event.  This is led by Texas, which is why the thick gray line (U.S. South Central region) has such a pronounced “hook” at the end.  Here’s Texas and the rest of the U.S. South Central states:

Three factors make it fairly clear that this is related to the storm. 

  • Texas (and possibly other states) had plainly said that they would be under-reporting cases due to the storm.  And the rate of new cases plummeted as they said.  And now we’d then expect a bump-up if case reporting merely returns to normal, let alone clearing any backlog.
  • This didn’t occur in regions that didn’t get hit by that weather event.  So (below) there were no increases like that in any of the U.S. South Atlantic states .  This is, by the way, also the reason you can be sure this isn’t the start of some Super-Bowl-related “explosion” of cases.  People watched the Super Bowl everywhere.
  • The timing is right for this be a reporting artifact (nearly immediate) , and not some actual change in infections due to that storm event.  Any increase or decrease in actual infections will show up a couple of weeks afterwards, due to various lags (between infection and symptoms, and so on.)


That said, the only unexplained part of this most recent uptick is that a lot more states reported upticks in cases than just Texas and nearby states.  It was not quite a 50/50 split between states that saw decreases and increases in the seven-day moving average of new cases per day.







The upshot is that if we attribute this entirely to last week’s cold-weather event, then we have to assume there were some sort of behavioral effects far beyond Texas and nearby states.  But for the moment, that’s just a little oddity.  It’s clear that the bulk of the recent uptick in case counts is just the post-weather-even rebound in new case reporting.

The final implication, per the second chart above, is that there hasn’t been any material change in the rate of decline in new cases per day since the start of the month.  We’re still on this more-or-less straight-line downward path.

On the one hand, I keep hoping that herd immunity plus vaccinations will soon drive the rate of decline sharply downward.  We’re finally seeing herd immunity get some play in the mainstream media, but so far I’m seeing zero indication that it’s starting to matter.

On the other hand, spread of the U.K. variant would halt and reverse the decline.

And so that’s where things stand, in terms of monitoring the U.S. third wave.  Track the line and wait to see which way it bends.