Transcript
mELtUXvnhIQ • How Coronavirus Tests Work I NOVA I PBS
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Kind: captions
Language: en
yeah it was quite painful you know when
you get a shot and it kind of like
pinches a little bit it was like that in
your nose the doctor comes to your car
and ask you a bunch of questions does a
physical exam with a stethoscope and
everything and then does the swab and
sends you on your way and that's it it
felt like you're snorting really spicy
mustard up one nostril is quite a shock
this is how most coronavirus tests are
done in the u.s. you stick a swab into
somebody's nose and you pull it out and
what's on it you have some of your cells
you have potentially virus to find out
if the virus is on that swab scientists
use a process known as polymerase chain
reaction PCR basically just a way of
taking a small amount of nucleic acids
specifically for the virus and turning
it into a lot of nucleic acids so that
you can detect it the new corona virus
contains RNA a single strand of genetic
information that sits inside a spherical
casing so the first thing you have to do
is to get into that genome so after the
swab what you will then do is take what
was on that swab and blow everything
apart chemicals are added to isolate any
genetic material and then you take that
tube and you subjected to PCR pieces of
genetic material called primers are
added to the tube
right so the primers are those small
pieces of DNA that are going and looking
for the genomic RNA and if the genomic
RNA is there those primers will bind and
that binding makes a landing site for
the enzyme to make that new copy this
happens over and over again creating
millions of copies as that new copy is
made now you get fluorescent molecules
coming in and binding to that new mathy
so if that snippet of coronavirus
genetic material is present PCR will
make lots of copies and fluorescent
molecules will make them glow that glow
means patient is infected in February
the CDC sent out test kits for this PCR
process but some of the chemicals didn't
work properly
what happens is is that for every test
you run a negative control which is a
sample that's supposed to be negative
that also tells you if the DES is
working if your negative control is
positive the whole thing you gotta throw
in the trash basically so what was
happening with the CDC test is that
there was a lot of false positives
particularly in the negative control and
that was due the impurities of the kiss
in March the FDA loosened regulations
allowing labs and commercial testing
facilities to use their own tests that's
really sort of a significant step and
that's what allowed us to go live with
the test but now there are more
challenges even just getting materials
to extract the RNA from the virus is a
problem right now every step of the way
we are experiencing bottlenecks
shortages of protective gear limit
healthcare workers ability to safely
take samples
and shortages of test kits and crucial
chemicals limit labs ability to test the
samples for the virus so every day when
I come into work the first thing I do is
start getting on the phone getting on my
emails trying to secure additional
supplies the kits themselves to all of
the testing materials we're basically
using all our materials much much faster
than we would like to most PCR tests are
run on machines at specialized labs that
process many samples at once some labs
are able to share results quickly and I
had mine in 18 hours Shelby says her
tests came back negative no I don't have
it some results have taken several days
I'm still waiting for my sera reports
her results came back an entire week
after her tests and we're all so
negative some new tests can be done much
faster in less than an hour but these
will likely be used primarily for
patients in hospitals and some
healthcare workers the FDA is warning
against new at-home coronavirus tests
calling them fraudulent
a completely different kind of test is
being developed to detect the virus by
looking for antibodies our immune system
goes into a very nice adaptive response
where it will identify the infecting
virus and make antibodies that have very
high affinity against it and those are
effective at blocking further infection
an antibody test could not only identify
who's been infected but also identify
who may have immunity those could be
people that are very important in our
response to the disease if they already
have an immune system that has seen the
virus and has developed an effective
response against it they might be people
that can help individuals that do need
assistance when they are sick scientists
are optimistic about improving capacity
to test for the virus using methods
currently in use I am optimistic about
the coming weeks I think we will get to
the point where we understand this virus
we have the diagnostic capacity as
multiple different companies are
approved and they ramp up their
production we should eventually be able
to meet the need the question is is that
two weeks from now or is that six weeks
from now that's the harder part to
answer