Post #1250: One week update on Virginia K-12 COVID-19 analysis

Posted on September 12, 2021


This here is what you call your basic non-result:

Source:  Calculated from Virginia Department of Health case counts by age and health district.  Health districts sorted into early-middle-late K-12 reopening by crosswalk to school districts.

See Post #1234 for the basic setup.  I’m using the staggered start dates of Virginia school districts as a “natural experiment”.

Here are the dates defining the early-middle-late starting areas:

We’re now well into the period when any uptick in infections in the early-start areas should be showing up in the data.  In those areas, school has been in session for more than three weeks now.

If the K-12 openings had a huge impact on COVID-19 spread, what we’d see is that the blue line above would bend up.  Then the red line.  Then the gray line.  At roughly one-week intervals.

Instead, what we see is noise.  There’s no pattern to the lines above.

Let me put this in perspective with the actual student COVID-19 case counts that Fairfax County, Virginia generates.  As of the most recently reported data (9/9/2021, almost three weeks after start-of-school), Fairfax reports:

The perspective is that there are about 188,000 K-12 students in the Fairfax County public schools (FCPS).  Doing the long division, cases reported by FCPS so far this year amount to 0.2 percent of school enrollment.

That’s a small percentage of the population, no matter how you cut it.

Assuming most other Virginia districts look like Fairfax, unless there is some massive uptick in cases, we probably aren’t going to see anything in this “natural experiment”.

In any case, so far so good.  Nobody can predict the future, but if you have children in school in Fairfax County or in the rest of Virginia, just keep this in mind the next time you see headlines screaming about COVID-19 outbreaks in K-12 schools.  Might be happening somewhere else, but right now, there’s no big uptick in cases in the under-20 population of Virginia.