Post #704 amended: Quick update to 5/29/2020, NoVA opening day

Source:  Analysis of county-level data as reported by the Virginia Department of Health.  NoVA plus is Northern Virginia, Richmond City, and Accomack County.  The latter is in the late-reopening group because because they had 500+ cases of COVID-19 in two poultry processing plants.


This post updates some key graphs, and gives a simple summary of where I think things stand on 5/29/2020, the day on which NoVA enters Phase I of re-opening. 

First, it now seems to be common knowledge that COVID-19 can be spread by asymptomatic (largely pre-symptomatic) individuals.  So the original CDC advice about avoiding droplets from those coughing and sneezing has pretty much gone out the window.  (I mean, sure, continue to do that, but that’s not really the issue at this point.)  In its place is a tacit acknowledgement that seemingly healthy individuals can spread the disease via short-range aerosol transmission, merely by talking or singing.  (If you don’t understand what aerosol (airborne) transmission is, see the reference on the front page of this website.)

And so, everywhere you look in the re-opening rules and guidelines, there’s an emphasis on doing your business outdoors where possible (e.g., restaurant seating), and on maintaining copious fresh air flow indoors whenever possible.  Both of those aim at diluting any aerosol droplets in the air, and neither of them makes any sense in the absence of risk of aerosol (airborne) transmission.  Whether they use that phrase or not, everybody has accepted that “airborne transmission” is a real risk, and is acting accordingly.

Second, accordingly, the Governor has instituted a mandatory mask policy for indoor public-access spaces such as stores.  Everybody needs to mask up, because you literally can’t tell who is spreading the disease and who is not.  In particular, you can’t tell if you, yourself, are spreading it.  But that’s going to be enforced by the Department of Health, which means that it will target institutions where that law is routinely ignored, not individuals.  That said, this gives every store in Virginia the clear mandate to require masks for all patrons.

Third, don’t lose sight of the fact that Phase I doesn’t really change much.  I went through all that in Post #696.  Logically, one reason we should not expect to see a lot of impact is that there really isn’t a lot of change.  Arguably, the largest change is for church services, where those can now be held in person at 50% of normal capacity.  Churches appear to be one of the most at-risk areas for potential superspreader events, so that will bear watching.  Otherwise, this really isn’t hugely different from the status quo.

Finally, as NoVA enters Phase I of re-opening of businesses, we seem to have reached a kind of steady state.   There is no longer any “exponential” growth (i.e., constant percent increase in cases, day after day).  So there is no longer any sort of “doubling time” to the cases.  Instead, we seem to be getting roughly the same count of new cases, week after week, in both Virginia, Fairfax, and Vienna.

Total cases, Vienna ZIP codes, counts for 22180 shown, updated to 5/29/2020

 

Here’s a contrast of the last two 10-day periods in the Vienna VA ZIP codes.

Orange is the count of cases — roughly the same for the past two ten-day periods, for the three Vienna ZIPS combined. Yellow shows tests per day.  This was actually a little lower in the current period than in the recent past.  Green shows fraction of tests that turned out positive, which was correspondingly higher in the current period than in the recent past.

(Caveat:  Tracking testing is tricky, because Virginia changed its reporting to exclude a small number of antibody-based tests from the counts, starting 5/18/2020. That’s why there’s a “memo” line stopping at 5/17/2020.

Daily new cases, Virginia and Fairfax County, last 28 days, updated to 5/29/2020. 

That’s averaging out to something under 1000 cases a day in the Commonwealth, something under 300 cases a day in Fairfax County.

Finally, here’s the 5/29/2020 update of the analysis of the impact of re-opening in Virginia.  At this point, we’re fully two weeks into the re-opening of the rest of the state (outside of NoVA, Richmond City, and Accomack County (which had 500+ cases in two poultry processing plants).  The red bar marks the point at which the counties reflected in the red line entered Phase I of re-opening.

If there’s any impact from Phase I, I surely can’t see it.