This episode was filmed on May 19, 2020.
If we have more recent videos about the pandemic,
you can find them in our COVID-19 playlist,
which we will link
in the top of the description.
[♪ INTRO]
None of us like to see the numbers of cases
and deaths from COVID-19
continue to climb.
But alongside those grim statistics is another,
slightly better one:
those who have been infected and recovered.
And thanks to a technique that’s more than
a century old,
those recovered patients may be in a position
to help
the rest of us -- with to their blood plasma.
We’ve successfully used transfusions of
blood serum containing
antibodies to a given disease as a treatment
since the late 1800s.
And it could work now, because the plasma
of patients who have
recovered from COVID-19 -- or any viral illness,
really --
should be chock full of antibodies that recognize
that virus.
Our immune system produces these antibodies
in order to recognize
and bind to viral antigens, or proteins on
the surface of a virus.
Even after an infection is over with, some
of these antibodies
remain behind in our blood.
In the 1890s, researchers in Berlin discovered
that they could
transfer these remaining antibodies from experimental
animals
to patients via blood plasma -- the fraction
of our blood
that doesn’t include red and white blood
cells.
They first tested this on animals by transferring
plasma
from guinea pigs that had recovered from diphtheria
to guinea pigs who were sick with it.
The piggies recovered once they received the
donor plasma.
Plasma transfusions work by conveying passive
immunity
to the recipient of the transfusion.
Because the donor’s body has created an
army of
super specific antibodies,
they can go
straight to work in the recipient -- without
waiting
for their body to make their own.
Researchers quickly moved on from guinea pigs
to adapt this new treatment for humans.
Horses were used as the plasma donors,
because of their relatively mild reaction to diphtheria --
and their high volume of blood.
Blood was extracted from a horse that had
mounted
an immune reaction to diphtheria.
Then, over the course of several days, the
plasma was purified
and injected into the recipient.
This revolutionary procedure was so effective
that it slashed the death rate from diphtheria
everywhere it was used
-- it’s estimated to have saved 45,000 lives
a year in Germany alone.
Emboldened by their success with diphtheria,
physicians in
the early 1900’s expanded the treatment
to use against
other diseases -- such as measles and the
1918 Spanish flu pandemic --
using plasma from either animals or recovered
human patients.
But while this approach was effective, it
was far from perfect.
It was common for patients to develop an allergic
reaction
to the plasma itself.
Also, since the antibodies aren’t made by
the recipient's body,
what you get is what you get.
They don’t stick around after the patient
has recovered,
so it’s only a temporary solution.
What’s more, researchers in the 1940’s
discovered
that blood itself can carry infections, and
those infections
could be transmitted between humans through
transfusions.
All that meant the sun was setting on plasma
transfusions,
in favor of something safer and longer-lasting:
vaccines.
Vaccines convey active immunity -- they work
by training
our own immune systems to produce antibodies
against a given invader.
That primes our immune system to go on the
offensive
if it ever encounters the actual disease.
At least, for a period of time -- some vaccines
do need to be re-upped with boosters.
But we don’t yet have a vaccine against
SARS-CoV-2,
the virus that causes COVID-19.
So blood plasma transfusions may be the ticket
to bridging the gap.
Technology has come a long way, and we can
now screen blood
to make sure it's not carrying infectious
diseases.
Plasma transfusions have already been shown
to be effective
against other coronavirus diseases, such as
SARS and MERS,
and early reports seem to show that’s true
for COVID-19 as well.
Hospitals have already begun using convalescent
plasma
as a compassionate use treatment -- a last
resort treatment
for critically ill patients.
And results from early clinical studies are
promising.
One study of ten critically ill adults, published
in April of 2020,
showed that patients’ conditions improved,
on average, within a week.
The researchers found high levels of antibodies
in the patients’ serum, and three of the
ten patients
were discharged from the hospital by the conclusion
of the study.
And for doctors looking to use this treatment,
the technology already exists -- it’s just
a matter
of access to plasma.
Plasma can be drawn from recovered COVID-19
patients using the
same plasma separation technology already
in place at blood banks.
Potential donors need to adhere to their country’s
guidelines
when donating plasma.
In the US, for example, they have to have
been tested positive
for COVID-19 and be symptom-free for 14 days.
There are some issues that still need to be
addressed
-- for example, early unpublished studies
suggest some people might
make more antibodies than others, and the
blood plasma has to be
the right match, because even plasma has to
be compatible
with the recipient’s blood type.
Though everyone in that study of ten people
got better,
other studies show positive outcomes are not
guaranteed,
so more data is needed to say for sure
that this is an effective treatment.
Fortunately, as we receive more convalescent
plasma donations,
more opportunities become available to test
its effectiveness.
Blood centers around the US are already seeing increased
traffic from donors who have recovered
from COVID-19
and want to do something to help.
And it seems like they can -- thanks to some
guinea pigs,
and a procedure that is more than a century
old.
Thanks to watching this episode of SciShow,
and thank you especially
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Your support is helping us keep people informed
during
a confusing and difficult time, and we are
so, so grateful.
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[♪ OUTRO]
