
Recovered virus patients retest positive due to 'dead' virus fragments: experts - lsllc
https://m-en.yna.co.kr/view/AEN20200429007051320
======
lend000
It's interesting, and somewhat reassuring that they mention people recovering
from the hospital after two months, as I believe I've had coronavirus symptoms
for about 6 weeks now without much change. My symptoms have never been quite
as severe as the last time I got the flu, but they show little change over
time. Lethargy, sore throat, pink eye, and mild fever are the primary symptoms
for me. I'll feel 95% better, then go for a walk and relapse for another week
and a half.

~~~
pvaldes
I noticed exactly the same dry cough, itching eyes, laziness and feeling tired
symptoms as you. Don't know If i'm positive, but I remain at home, avoid
contact, and wash the hands often, just in case.

Flu-like hitting hard in December or so (before the start of the problem), and
ripples all the way since that. I don't know if is coronavirus or other thing,
but the recurrency of the symptoms is puzzling. Could be just a spring allergy
also of course. No fever at all.

~~~
beervirus
If it started in December, it's probably not covid 19. If you don't have a
fever, it's probably not covid 19.

~~~
vmception
probably but not completely discountable.

its _because_ people have been saying "hey what about this" despite the loud
banging of the scientifically minded people yelling "NO EVIDENCE THEREFORE ITS
AN ABSURD IDEA" that we know of a _community spread_ case in the US that died
on February 6th. Instead of a _travel related_ case that died on February
29th.

so then was patient zero in US from travel on January 15th? January 1st?
December 15th? December 1st? How many hops are really necessary

~~~
drran
If patient died at Feb 6th, then it contracted covid about 1 month before that
from somebody else, so Jan 1st, maybe.

~~~
vmception
I was going with 3 weeks, but yes early January like 2nd week 6th - 12th

and if that person was also community spread or travel spread then we are
looking at mid-december either way.

------
doctoring
This has been hypothesized for some time, as it is a phenomenon seen in other
respiratory viruses (indeed in other viruses in general) where your test is
detecting a fragment of virus. These fragments persist after clinical
recovery, and, combined with imperfect sensitivity/specificity of your test,
can show a pattern of "re-infection": positive test during illness, negative
test during/after recovery, then positive test again later.

The gold standard (sort of) for whether the actual virus is there is isolation
and "culture" of virus from a swab using, say, a petri dish. But unlike (most)
bacterial pathogens, this process is laborious, requires actual relevant cells
(many bacteria just grow in goop like Agar) and is slow. (Alternatively you
could just try to infect someone else! And if that second person can
subsequently infect someone else, then you've shown the virus was there in the
first person. And the second person. Sorry, second person.)

Empirically in hospitals we've been seeing a couple of patients retest
"positive" but haven't seen any get sick or re-hospitalized, so that's also
reassuring.

~~~
Nav_Panel
As far as I can tell, this paper from Germany actually took the time to detect
live virus vs PCR positive:
[https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v...](https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v1)

They found that, for all patients in the small study (N=16), none tested
positive for infectious virus after day 8 post-onset, despite testing positive
for the virus in RNA over 2 weeks after illness onset. This, to me, is
encouraging.

------
kragen
Is there a better source for this than a report of a press conference? Like, a
paper? The KCDC is highly competent, and maybe the English-language Korean
press isn't as bad as the US press ("Is this going to be a deadly pandemic?
No." "The flu killed more people." "Healthy people wearing masks doesn't
help.") but I really have no way to judge. And I've been burned too many times
this year already by trusting the ignorant dabblers we call journalists.

~~~
dba7dba
To learn more about coronavirus, treatment and vaccine development from the
perspective of doctors in S. Korea, try watching these interviews in order.
Each is about 30 - 50 min long. I posted the links and the dates they were
uploaded. The videos are excellent because the doctors are not interrupted
with questions.

1) 2020.03.27

1st interview with Professor Kim, leading expert on coronavirus in Korea. In
Korean with excellent English subtitles.

[https://www.youtube.com/watch?v=gAk7aX5hksU](https://www.youtube.com/watch?v=gAk7aX5hksU)

2) 2020.04.14

2nd interview with Professor Kim, leading expert on coronavirus in Korea. In
Korean with excellent English subtitles.

[https://www.youtube.com/watch?v=QwoNP9QWr4Y&t=1081s](https://www.youtube.com/watch?v=QwoNP9QWr4Y&t=1081s)

3) 2020.04.25

Interview with the Director General of the International Vaccine Institute
(IVI) about COVID-19 Vaccine. It's in English.

[https://www.youtube.com/watch?v=5cYWd0N8nO4&t=120s](https://www.youtube.com/watch?v=5cYWd0N8nO4&t=120s)

4) Note in the interview with Prof Kim uploaded on 2020.04.14, they were still
not sure if a recovered patient testing positive again was due to
reactivation/reinfection or not. They were still trying to confirm it as of
2020.04.14.

But it seems the yna.co.kr article posted on 2020.04.29 confirms recovered
coronavirus patients may have tested positive again due to traces of virus
fragments that have been inactivated.

5) I'm hoping the Youtube channel will upload another interview with Prof Kim
about covid-19 soon.

~~~
kragen
Interviews with doctors are interesting from a human empathy perspective, but
I really want to be reading papers, not watching interviews, and I want the
papers to be by epidemiologists, not just doctors.

~~~
funcDropShadow
Maybe, the following research papers from germany's top expect on Sars-Cov-II
are interesting to you: \-
[https://www.nature.com/articles/s41586-020-2196-x?utm_source...](https://www.nature.com/articles/s41586-020-2196-x?utm_source=twitter&utm_medium=social&utm_content=organic&utm_campaign=NGMT_USG_JC01_GL_Nature)
\-
[https://www.nature.com/articles/s41564-020-0695-z](https://www.nature.com/articles/s41564-020-0695-z)

and his latest article, on Twitter yesterday:
[https://zoonosen.charite.de/fileadmin/user_upload/microsites...](https://zoonosen.charite.de/fileadmin/user_upload/microsites/m_cc05/virologie-
ccm/dateien_upload/Weitere_Dateien/analysis-of-SARS-CoV-2-viral-load-by-
patient-age.pdf)

He is also doing a podcast with already 37 episodes about Covid-19, but it is
only available in German. But the German transcripts contain links to articles
he discusses. And those are articles he deems good enough to discuss them in
public, even though they are often just preprints.
[https://www.ndr.de/nachrichten/info/Coronavirus-Update-
Die-P...](https://www.ndr.de/nachrichten/info/Coronavirus-Update-Die-Podcast-
Folgen-als-Skript,podcastcoronavirus102.html) -

~~~
kragen
While these three papers are indeed good and valuable, they do not seem to
mention Korea or touch on the question of why, and how often, rt-PCR tests
continue to return positive after remission of symptoms, and in particular
whether these apparently reinfected patients are contagious. I am not sure why
you mentioned them.

------
paypalcust83
So I assume they're using a cheaper ELISA test to look for IgG/M first if the
patient is known recovered or asymptomatic, but then how could rtPCR protocols
create false positives transcribing viral RNA unless the primers, probes, or
matched regions are too small? Are they matching un-encapsulated RNA
fragments?

Is there the a type of in vitro protocol for measuring viral infectivity
potential of a sample?

~~~
nraynaud
Yes, you can cultivate the right human cells and infect them. I suspect this
kind of thing would be restricted to the highest security laboratories,
because you’d be actually multiplying the virus in its infectious state.

------
tunesmith
Does anyone know when the contagious period (for a single covid infection)
tends to end? Are you contagious the entire time you have symptoms? Beyond
that point? ("Viral shedding" doesn't necessarily mean contagious.)

~~~
Gibbon1
Diane Havlir Professor of Medicine and Chief of the HIV/AIDS at Division at
UCSF gave a presentation where she said they can't culture virus 8 days after
symptoms. And that viral fragments can be detected for weeks.

Source: [https://youtu.be/bt-BzEve46Y?t=435](https://youtu.be/bt-
BzEve46Y?t=435)

~~~
tunesmith
Thanks, that's interesting. Given an infectiousness period, it seems you can
relate R0 to doubling time.

Like, if R0 is 2, that means each patient (on average) infects 2 others, but
during the period of time they are infectious. So that would mean 2 others
over the course of 10 days (8 days post-symptom, 2 days pre-symptom).

~~~
Gibbon1
Someone else either in this video or one of the others they said viral
shedding in COVID19 is a 1000 times higher than SARS. There is a paper up on
the CDC website that estimated r0 between 3.8 and 8.7, which is much higher
than initial estimates. Matches the observation that in crowded indoor
locations (nursing homes, prisons, homeless shelters, cal centers) everyone
becomes infected within days to a week.

UCSF's grand rounds on covid19 go up every Thursday. Upside, high quality
distilled information. Downside, hour and a half long.

------
war1025
This is excellent news.

------
rurban
We knew this for about two months, and now they are posting it on April 29.
These PCR tests are overly precise and pick up dead bodies of RNA chains of
length 600. The whole chain is 32K. But when cut into pieces by the immune
reaction it's still being picked up and falsely flagged as active. So people
were falsely worried that they could get reinfected and infect others. Those
claims constantly showed up on fake national news.

------
a3n
But ...

Are those fragments still able to transit from person to person (through
whatever route), and might your immune system still react to it and then
sicken or kill you?

~~~
CyanLite2
No. The RNA fragments must be encased by a lipid "bubble" with the spike
protein receptors in order to invade and replicate within your cells. Even if
you somehow injected these fragments directly into your bloodstream, your
immune system and kidneys would easily destroy these waste particles and flush
them out because they are not replicating. They're essentially the 'dead
carcass' of this virus.

------
simonsarris
yay:

> The committee further said it is virtually impossible for the virus to be
> reactivated unless the COVID-19 virus causes chronic infections.

> "The COVID-19 virus does not invade inside of the cell nucleus and combine
> with a patient's DNA," Oh said. "It means that the virus does not create
> chronic infections."

> Oh further said the COVID-19 virus is different from diseases such as HIV
> and hepatitis B in which the virus stays dormant inside of a cell nucleus
> and later causes chronic infection.

------
TheBlight
I wonder if this gets the CNN headline treatment like the original story
did...

------
abracada_toss
good news ... i think then vaccine will work?

------
alejohausner
In other words, when you recover from covid-19, you are immune to it. In other
words, covid-19 is just like every other virus, in this respect.

Governments around the world have reacted with terror to this pandemic, but
that doesn't mean the virus is some sort of strange monster. It's extremely
infectious, and somewhat more lethal than influenza. That's all.

When I first heard about those patients who had recovered from the virus, and
yet were still testing positive, it felt like a mistake. I'm glad it's been
cleared up.

~~~
kleiba
_In other words, when you recover from covid-19, you are immune to it_

How does this follow?

~~~
AnimalMuppet
I think it's an overstatement. When you recover from it, you don't still have
it, even if you test positive. That means that at least some of the "got it a
second time" reports are false.

Are they _all_ false? Don't know. There's hope, but not yet evidence, so far
as I know.

~~~
pbhjpbhj
What evidence are you using to show people have recovered who are still
testing positive? What confirms that the positive test is false?

Can you provide some sources?

~~~
Mikeb85
Is this a joke? Literally the article at the top.

~~~
pbhjpbhj
No, not a joke, you seemed to be talking from a general perspective rather
than "in the results in this particular PCR test in South Korea". As if you
had generally applicable information.

My understanding was there were many different tests being used ... so on what
basis are you making that generalised statement.

> When you recover from it, you don't still have it, even if you test
> positive. //

A plausible explanation for specific tests doesn't make this a universal
truth; so presumably you are relying on more information? Also, there being an
explanation for positive tests based on dead virus, doesn't mean all post-
infection positive tests are due to dead virus; that's a massive assumption.

------
econcon
And why dead fragments can't join again to make full blown virus? Sure it
seems theoretically possible, given enough number of patients - sooner or
later, new virus will rise up like phoenix from ashes.

~~~
bpodgursky
Viruses don't work that way.

Even if they did, it's not the point -- the presumption is that the immune
system would handle them like it treated live viruses, with antibodies and an
immune response. The point is that this isn't a second infection, it's dead
fallout from the first one, and the patent is likely immune against
reinfection.

~~~
clairity
it's not even that viruses don't work that way, entropy doesn't work that way.

~~~
greenshackle2
You mean you _don 't_ assemble Lego models by putting all the pieces in a box
and vigorously shaking it?

~~~
quxbar
I have an infinite team of monkeys working on it...

~~~
prox
That is what my Boltzmann brain just told me

