Post #1032: William and Mary COVID-19 testing rate.

 

I tried to do a quick comparison of the COVID-19 testing rate on the William and Mary campus relative to the testing rate in Virginia.  The ultimate goal of this is to (gu)esstimate the effect that more intensive testing of the W&M student body has had on the count of COVID-19 cases discovered.

Turns out, that’s a very hard thing to do, for a lot of different reasons.  That’s not going to stop me from giving an estimate.  But it does stop me from giving  good estimate.

Best guess, the mandatory testing regimen at W&M ought to identify about three times as many cases as the voluntary, symptom-driven testing found in the community.  The fact that it does not — that we don’t see a case count that is three times the community rate — probably reflects the self-selection of the W&M student body, and the fact that their pre-campus COVID-19 infection risk is (probably) much lower than that of the average 21-to-30-year-old Virginia resident.

For me, the bottom line remains the same:  I want to see W&M improve, relative to that community benchmark, as the semester progresses.  That’s how I’ll feel comfortable that W&M is controlling the spread of COVID-19 on campus. Continue reading Post #1032: William and Mary COVID-19 testing rate.

Post #1030: Magid N95 respirator, a flat-fold mask with excellent face seal

This is the followup to Post #1023, my latest N95 mask purchase.

After looking over what was routinely available, my most recent purchase of N95 masks was 10 of these foldable Magid N95s, from Amazon.(And not these, which is now the Amazon listing for a hard-cup mask)  The reasoning was pretty much the same as for my last purchase.  These are certified for industrial use, they are not certified for medical use, and they are an odd, niche style.  It doesn’t seem like it would be worth anyone’s while to counterfeit them. Continue reading Post #1030: Magid N95 respirator, a flat-fold mask with excellent face seal

Post #1029: Post Super Bowl non-explosion of cases

Source:  Calculated from NY Times Github COVID-19 data repository, data reported through 2/24/2021.  Areas are defined as the counties currently within the Tampa/St. Petersburg and Kansas City KS/MO MSAs.

So far, I have found exactly one news article that actually followed up on the dire threat of a post-Super-Bowl explosion of cases.  That one, lonely piece of reporting was from a TV station in the Tampa Bay area.  Their conclusion is that, no, there was no uptick in cases following the Super Bowl.  At least, not in the Tampa Bay area. Continue reading Post #1029: Post Super Bowl non-explosion of cases

Post #1027: A correction on my William and Mary calculation

Same story as before, just a different baseline.  The upshot is that the red line — the expected count of new COVID-19 cases — should be based on 70% of total student enrollment.

And as a result of that correction, W&M’s COVID-19 incidence is not much different from what you would expect, based on the community rate.  But it’s not (yet) better than you would expect.  At the current rate, it’s going to take another week or two to get there.

Details follow. Continue reading Post #1027: A correction on my William and Mary calculation

Post #1026. Has the six-week downward trend bottomed out?

I’m not sure I can blame Texas for all of the recent change in the COVID-19 new case trend.  Today it’s starting to look like the steeply downward trend of the past six weeks is bottoming out.

Let me do something a little out-of-order here.  Take a look at the picture below.  See the little upturn in the case count that just happened?

Continue reading Post #1026. Has the six-week downward trend bottomed out?

Post #1025: Trends, reporting artifact from winter storm

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.

Post #1023: Next N95 mask purchase

Currently, I’m wearing the Kimberly-Clark N95 duckbill, on sale at Amazon for $52 for a bag of 50.  This was my choice for an N95 mask purchase, for several reasons:

  • Solid evidence that these are genuine (read the Amazon comments).
  • Reputable US manufacturer (Kimberly-Clark)
  • Reputable seller (Amazon), available from other reputable vendors.
  • Industrial mask not suitable for hospital use (NIOSH-certified but not FDA-certified)
  • Cheap, at $1/mask.

When you add all that up, what that mostly means is that there’s not a lot of profit in trying to counterfeit these.  Continue reading Post #1023: Next N95 mask purchase

Post #1022: Trend to 2/21/2021, now 74% below the peak.

Today I’m including the full set of charts, including state data by region.

In summary:  We’re 74% below the peak in new COVID-19 cases per day.  Rate of decline slowed a bit in the last two days, and the crude stock-market-style winners/losers table (count of states with a one-day decline in new COVID-19 cases) fell.  Not sure if that’s significant, or is just largely a consequence of the situation in Texas and nearby states stabilizing.

Graphs follow.

Continue reading Post #1022: Trend to 2/21/2021, now 74% below the peak.