The Clinical Lab Test for the COVID-19 Virus


Rodney Rohde is the head of
the Clinical Laboratory Sciences department at Texas State University here in San
Marcos.  His department is where people
go to learn how to run the horrendously complicated tests that clinical labs
do, such as the CDC 2019-novel coronavirus (2019-nCoV) real-time RT-PCR diagnostic
panel.  That’s the official name for the
CDC’s test for the coronavirus.  I
wouldn’t know even that unless Rodney had directed me to the CDC website, where
you can download the entire 48-page instruction sheet for using the test.

This is no dip-the-stick-and-look-at-the-color
test.  First you have to get the
reagents, which were in short supply, and according to some reports, some early
sets of test kits were defective.  (Some
day, when everything goes back to the new normal, whatever that is, somebody
will dig around and find out exactly what went wrong.  But not right now.)  Assuming you’ve got a good set of reagents,
and a clean-room-quality lab that has been disinfected from any kind of
biological stuff that could contaminate the phenomenally sensitive test, and a
96-well cold plate at -20 C, and an Applied Biosystems 7500 Fast Dx Real-Time
PCR System with SDS 1.4 software, and “molecular-grade water,” whatever
that is, and a bunch of gloves, gowns, pipette tips, centrifuges, and a lot of other
expensive and delicate equipment, you can start doing the test—that is, if you
know what you’re doing, which means you have to have passed courses in Prof.
Rohde’s department or equivalent.  There
are not that many of such trained people around.

A lot of these reagents have
to be kept at -20 C or colder because the heart of the operation, the polymerase
chain reaction (PCR) that doubles the number of virus-derived DNA molecules for
every heating-cooling cycle, is temperature-sensitive. 

Imagine following an
instruction sheet for assembling an IKEA table, directions for installing new
software on your computer, and filling out your own long-form tax return all at
once, while balancing a spoon on the end of your nose.  That’s easy compared to running this
test.  Of the 48 pages, 23 are the actual
instructions of how to run the test, down to which button to press and where
not to put the labels on the test vials. 
Each sample produces some lines on a logarithmic graph that rise with
each cycle of the doubling reaction.  A
positive result is when two of the lines cross a threshold after 45 cycles.  Did I mention that each heating-cooling cycle
takes several minutes and has to be controlled in temperature extremely
closely, or else the whole thing screws up and you have to start over?  Once you’ve loaded the samples into the
machine after doing a bunch of fiddly aliquot combining and dilutions and
agitations, the machine runs for an hour and twenty minutes, and if you’ve done
everything right, you get valid results. 
But if one of the quality-control checks indicates contamination or some
other problem, the whole set of tests has to be thrown out and you start over.

It takes a very particular type
of person to do this fantastically complex yet repetitive stuff correctly day
after day, week after week.  My friend
Rodney is one such person, and we who are anxiously awaiting the next phase of
this crisis should pause to thank every clinical lab worker who is doing this
kind of job.  They are probably not
pausing from work right now for anything except to eat or sleep every so
often.  The amazing thing is not that the
CDC sent out some defective kits early on, but that the whole complicated
rigmarole ever works at all.  But it
does, and many lives depend on how well, and how fast, and how many tests are
done right in the coming days and weeks.

As others have said, the U.
S. lost precious time in early February when the first COVID-19 cases showed up
here.  The winner in this regard is South
Korea, as The New Atlantis editor Ari Schulman points out in an
editorial posted at that journal’s website. 
I can endorse his opinion, because what convinced me that the U. S. was
basically flying blind in this crisis was a chart I found a week or so ago that
described the number of COVID-19 tests administered per million population as
of March 11.  The leader was South Korea,
with I think several hundred per million. 
The U. S. was about the lowest on the list, with only 23 per million population
tested by then.  That meant we had no
idea who had the disease, comparatively speaking.

Schulman says that the South
Koreans never had to shut down their country, because they did three things
early enough:  (1) They performed massive testing of both ill people and well people who thought
they might have been exposed; (2) officials performed rigorous contact tracing
to find the sources of the infection and tested them too; (3) infected persons
were rigorously isolated until they recovered. 
South Korea is now on the downhill side of their new-infection
curve.  They continue to be highly vigilant,
but life was never shut down there like it is being shut down here, and it
looks like they won’t have to do that at all.

We do, because, well, never
mind why.  Recriminations are pointless.  Schulman’s main point is that we need a
definite criterion from our national leaders as to how we will know when we can
ease up on the national shutdown.  Is it
that new COVID-19 cases are decreasing? 
That essentially no new cases are showing up?  Or what? 
He’s concerned that if the shutdown goes on indefinitely, a backlash
will happen that could be worse than doing nothing.

In the meantime, you now have
a wide choice of online church services to attend.  Prayer has never been more popular online. Some people are saying that this whole thing
is going to be what unites us as a country again.  God has a way of doing good things with bad
situations, and that would be a welcome outcome.  But first we have to get through it, and
here’s hoping and praying that those who are performing the critical testing
can do their jobs rapidly and accurately, and that we use the test results to
end the epidemic sooner rather than later.



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