Category: COVID through 2022

All my various postings tracking the COVID-19 pandemic through the end of 2022.

Post #1041: Trend to 3/3/2021, and the curious case of the British lockdown.

The US fell slightly below 20 new COVID-19 cases per 100,000 persons per day.

Otherwise, there is no material change from yesterday.  The majority of states continue to see small day-to-day reductions in new cases.  The Northeast as a whole does not, due mainly to New York and New Jersey.  By contrast, large reductions in new case counts continue unabated in California.

If I were to start a new calculation, from the point at which Texas’ data reporting had recovered fully (2/27/2021), the results would look like the box in the first graph.  The Northeast is stalled, California is not, and all other regions fall in-between. Continue reading Post #1041: Trend to 3/3/2021, and the curious case of the British lockdown.

Post #1040: U.K. variant: The fuse remains lit. Keep your eyes on Florida.

Source:  Clipart-library.com

Putting aside for a moment the New York COVID-19 variant (which people claim is more contagious, a seemingly plausible claim based on the new-case trend in New York state),

and ignoring the California COVID-19 variant (which ditto, but if so, it’s surely not affecting the new case trend there, as California has the largest rate of decline of new COVID-19 cases in the nation),

and just forgetting about the South African variant as not being common enough in the U.S. yet,

(and fill in other variants at will here, because you’ve got plenty to choose from),

The granddaddy of COVID-19 variant problems for the U.S. is the U.K. variant, B.1.1.7.  Continue reading Post #1040: U.K. variant: The fuse remains lit. Keep your eyes on Florida.

Post #1038: William and Mary COVID cases through 3/1/2021

As of yesterday, the total number of COVID-19 cases on the William and Mary campus this semester more-or-less matches what I would have expected, based the rate  in Virginia for young adults.  Like so:

This tells you that they’ve achieved that in terms of total cases, but this doesn’t show you when W&M got the rate of spread down.  To look at that, let me divide this up week-by-week and look at the weekly increase in cases.  Like this:

The first week with the entire student body back, they found a lot of new cases on campus.  (The first blue bar is much taller than the first orange bar.)  But after that first week, the rate of spread of COVID-19 has been lower on the W&M campus than it was for young adults in Virginia as a whole.  In fact, that situation has gotten progressively better.  By the 4th week, the rate of new cases on the W&M campus was less than half that of Virginia young adults as a whole.

If I had to guess, the first week looks the way it does because W&M tests for COVID at a vastly higher rate than Virginia does (Post #1032).  And it’s a fair bet that most of what was identified in that first week was cases that came onto the campus with the newly-arriving students, and not cases that were contracted while students were on the campus.

(How could there be any cases at all, since everybody had to pass their pre-move-in testing?  These are infections that would have occurred too late to be caught by the pre-move-in screeing, plus a non-negligible number of false negative on that pre-move-in screening test.  (Again, see Post #1032, or Post #859 to see the high false negative rate of COVID-19 PCR testing.)  If test samples were taken  an average of 7 days prior to move-in, you’d expect to have at least 10 days’ worth of new infections within the move-in population.  Most (but not all) of those would get picked up with the initial round of post-move-in testing.  It’s not all because the post-move-in testing would also have a non-negligible number of false negatives.)

The upshot is that the COVID-19 situation at W&M appears to have been under good control pretty much from Day One.  And, as was true last semester, I can make the case that my daughter is safer at William and Mary than she would have been at home.  Or, at least, safer than the average young adult in Virginia.

 

Post #1036, new COVID-19 cases trending down slowly, ex-Texas

Today is probably the last time I’ll show the trends with and without Texas (and LA and AR).  At this point, the (seven-day moving average of) Texas data reporting appears to have recovered fully, and it’s only distorting the historical data.

If you include Texas (and LA and AR), cases are rising at a rate of about 4%/week starting 2/21/2021.  But that reflects the data reporting outage in Texas (and surrounding areas) due to the mid-February cold wave.  And then the recovery from that outage.

If you exclude TX, LA, AR, you find that cases have been falling about 4%week, starting 2/21/2021.  That’s almost certainly a more accurate picture of the underlying trend. Continue reading Post #1036, new COVID-19 cases trending down slowly, ex-Texas

Post #1035: Herd immunity, part 1: Vaccines don’t matter, much, yet

It’s about time to revisit herd immunity.  So far, all I’ve been able to say, from the data, is that we’re not there yet.  (Duh.)

I’m going to start off this next set of posts by explaining why the current vaccinations don’t matter (much, yet) in terms of getting individual states or the U.S. as a whole to the herd immunity level. Continue reading Post #1035: Herd immunity, part 1: Vaccines don’t matter, much, yet

Post #1034: Trend to 2/26/2021, flat ex-Texas

Texas and some nearby states had severe difficulties in processing their COVID-19 case counts during the mid-February winter weather event.  That, combined with the use of seven day moving average data, means that their case counts are only now returning to normal.  You can see that reflected in the gray line on the first graph below, for the U.S. South Central states.  Including that data reporting effect makes it appear that new COVID cases are on the rise.

But excluding Texas (and Louisiana and Arkansas), cases are flat-to-down.  There’s still a sharp inflection point at 2/21/2021.   The decline in daily new case counts ceased at that point.  But so far, that’s been replaced with more-or-less stable new case counts. Continue reading Post #1034: Trend to 2/26/2021, flat ex-Texas

Post #1033: Will we ever get public health officials who can do simple arithmetic?

Or who can be bothered to look at simple data analyses before holding a press conference?

What sets me off today is this CNBC article in which the U.S. CDC director tells a story about the recent bottoming of the third U.S. wave of COVID.  Apparently the spread of the U.K. variant is to blame, because, at least according to this article, that now accounts for 10% of cases. Continue reading Post #1033: Will we ever get public health officials who can do simple arithmetic?