8 ms·

South Korea reports recovered Covid-19 patients testing positive again

58 points by abhiminator 7y ago

ceejayoz 7y ago
Do we have any data on South Korea's tests and their false positive/negative rates? Even a couple percent would lead to several cohorts of "tested positive but weren't" and "tested negative but still were actually positive", I'd think.
drocer88 7y ago
Key passage from the text: Kim also said patients had likely “relapsed” rather than been re-infected. False test results could also be at fault, other experts said, or remnants of the virus could still be in patients’ systems but not be infectious or of danger to the host or others. “There are different interpretations and many variables,” ...
- _wldu 7y ago
  Many of the COVID tests are not cleared/approved or even authorized for emergency use yet. But, this is what we are having to rely on to count confirmed cases due to the circumstances. https://www.questdiagnostics.com/dms/Documents/covid-19/SARSCoV-2_Patient_Fact_Sheet.pdf https://www.questdiagnostics.com/dms/Documents/covid-19/SARS... "Is this test FDA-approved or cleared? No. This test is not yet approved or cleared or authorized by the United States Food and Drug Administration (FDA). When there are no FDA-approved or cleared tests available, and other criteria are met, FDA can make tests available under an emergency access mechanism called an Emergency Use Authorization. Quest Diagnostics is working with FDA to obtain Emergency Use Authorization." And the tests that are authorized for emergency use are not FDA cleared or approved. "Testing was performed using the cobas(R) SARS-CoV-2 test. This test was developed and its performance characteristics determined by LabCorp Laboratories. This test has not been FDA cleared or approved. This test has been authorized by FDA under an Emergency Use Authorization (EUA). This test is only authorized for the duration of time the declaration that circumstances exist justifying the authorization of the emergency use of in vitro diagnostic tests for detection of SARS-CoV-2 virus and/or diagnosis of COVID-19 infection under section 564(b)(1) of the Act, 21 U.S.C. 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner."
  - pmoriarty 7y ago
    On the subject of unreliable tests, here's a transcript of a letter read on episode 588 of This Week in Virology[1]: I'm an infectious disease doctor and would like to point out an important factor in diagnosing this infection (and all respiratory pathogens that use nucleic acid probes for specimen collection). This is of particular concern now that China has transitioned to a much more problematic clinical diagnosis based more on clinical symptoms than PCR testing. While it may seem trivial how a health care worker jams a swab in to someone's throat or nose, technique is important. If anterior naries (front of nose) swabs or side of mouth swabs are done, rather than the true posterior nasopharynx or oropharangeal swabs, the sensitivity drops dramatically. We have shown this to be true repeatedly with diagnosis of influenza and respiratory pathogens, and I am disappointed that it has not been mentioned more in discussions about the PCR tests, missing the diagnosis in people who are positive and negative then positive again. We often see people admitted from the ER with the perhaps carelessly collected flu test who miraculously are flu positive by the time they are admitted. Like so many cultures and diagnostics in infectious diseases, specimen collection and handling is critical. I warn my patients about the unpleasantness of a nasopharangeal swab and jokingly tell them that if it doesn't cause a wincy-face reaction we haven't collected specimens from where the viruses reside. [1] - http://www.microbe.tv/twiv/twiv-588/; http://www.microbe.tv/twiv/twiv-588/; at about 1 hour and 38 minutes in
    - macintux 7y ago
      I had one of those nasopharyngeal swab tests conducted about a month ago for the flu. It was extremely unpleasant, so I can concur with the good doctor, albeit astonishingly brief.
  - icegreentea2 7y ago
    The EUA-ness of the test has very little to do with re-positives. RT-PCR tests can only test for the presence of viral RNA in the sample collected. They cannot tell you the viability of the viral particles, they cannot tell you if you going to get sicker, or going to get better the next day. We don't even fully understand the relationship between vRNA detection and contagiousness. And all of those unknowns are outside of the scope of the test. Even in normal times, these tests can only be used to determine if genetic material exists (and sometimes the quantity if the collection mechanism and processing are controlled enough). It must be left up to clinicians to interpret these results. The current protocol is to wait for 2 consecutive negatives 24 hours apart to call someone virus free. That's a protocol created by clinicians in a time of extreme pressure and need based on empirical measurements and prior body of knowledge. A 510k cleared COVID test would have most of the same issues because the problem isn't strictly that the tests can't reliability detect viral particles, the problem is that we don't know what actually constitutes "cured".
- fmjrey 7y ago
  A bogus test would explain a lot of oddities such as a high number of asymptomatic cases and testing positive again after recovery. It would help to know what is being tested exactly: are we sure we isolated that virus, how specific is the sequence being tested?
jliptzin 7y ago
Could this turn out like HIV where there is an initial infection period followed by some dormant period and then another period where it causes more problems for the host again?
- SpicyLemonZest 7y ago
  It's unlikely. Coronaviruses are well-known and well-studied, so we can be pretty confident that the disease will just be a single respiratory tract infection rather than anything weirder.
- yyyk 7y ago
  Possible but unlikely since this is an RNA virus (unlike HIV) which shouldn't be able to 'hibernate' in cell DNA. If it can still be dormant - where would it 'hide'?
jrockway 7y ago
What is our plan if Covid-19 doesn't go away after you recover from an infection?
- snissn 7y ago
  i think our plan would be to come up with a new plan
- jdavis703 7y ago
  Something like PREP (anti-HIV drug for people in high risk groups) probably. There also might be a lot of deaths and suffering if it takes a long time to create a coronavirus prophylaxis medicine.
- 12yrprogrammer 7y ago
  No politician wants to say it, but the plan regardless was to quarentine until a vaccine comes out in 1 or 2 years. That or accept the 0.5 percent death rate with the "flatten the curve" method where we all catch it. Your concern means we'd only have situation 1, quarentine for 1 or 2 years.
  - TaylorGood 7y ago
    Logic says this too. Deadly, contagious virus with no vaccine, which takes roughly 18 months. There aren't too many options. I've heard chatter that big co's started telling their employees they're planning 18 months WFH.
    - rpiguy 7y ago
      Logic says just to live with it like we live with the flu and go on with life. The mortality rate is comparable. CDC is projecting 60K deaths if we open up most of the economy by the end of May. In the 2018-2019 flu season flu killed 80,000. Once the disease surge in densely populated ends areas it appears to become quite manageable.
      - yyyk 7y ago
gnulinux 7y ago
Layman here. Curious: if this is true, that you don't gain long term immunity to SARS-2 by catching COVID, would that have any implications on potential vaccine in the future? Does this mean, this virus is something we cannot build a vaccine for? Does this mean even if we have an approved vaccine, it would likely have a very low probability to protect us? Or do RNA vaccines work in a way that affects our immune system that's entirely different than how immune system builds immunity against the virus itself?
- ping_pong 7y ago
  There was an experiment done a few weeks back where they infected rhesus monkeys with SARS-CoV-2 and the monkeys were subsequently immune. So the idea that we humans don't get some amount of immunity would be hard to believe. https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1 https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1
RyanShook 7y ago
Isn’t the concept of someone being reinfected with the exact same virus basically unheard of?
- pcr0 7y ago
  No, herpes, chickenpox + shingles would be the counter examples.
  - nkohari 7y ago
    In my understanding, herpes and varicella (chicken pox/shingles) are thought to be "reactivations" of dormant viruses, not reinfections. The virus is never fully eliminated, and sometimes it becomes re-activated.
- mythobit 7y ago
  I'm not certain if you are talking specific to coronavirus, but it is not unheard of with viruses. For example, chickenpox/shingles or herpes.
- throwaway5752 7y ago
  We have coronaviruses. There is no "cold" virus really and it's an umbrella term for a few different viruses including coronaviruses. With human adapted coronaviruses - unlike zoonotic covid-19 - you don't get lifetime immunity https://www.ncbi.nlm.nih.gov/books/NBK7782/ https://www.ncbi.nlm.nih.gov/books/NBK7782/ You can just think of booster immunizations and getting tetanus shots when you're exposed. Why would you need those, otherwise? If you want to learn more looking into memory T and B cells.
Nav_Panel 7y ago
Where's the study and data? What's the time frame we're looking at here? This German study (https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v1 https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v... -- see the graphs near the end of the PDF) suggests that viral RNA may be detectable in recovered patients for 3 weeks after symptom onset, or longer (the study seemed to stop testing after 3 weeks, despite some recovered patients still testing positive for viral RNA). But they were unable to isolate live virus after about a week post-onset. Could this be what we're seeing? If you're still worried, I recommend looking at this small study on macaques designed to test immunity (https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1 https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1). They found that the macaques did develop immunity and were able to fight off the virus on reinfection. If we compare with the this study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/) on the development of immunity in response to the original SARS virus (I'm not sure on the exact mechanism of immunity, but if the body's immunoglobulin response targets the spike protein, then it's probably similar), we should probably expect antibody production to continue at least a year after infection, if not for 3-4 years after.
angel_j 7y ago
I feel like we're about to learn way more about viruses than we thought we knew. It's like how NYTimes "scientists" only recently learned that gut bacteria is our friend...
emersion 7y ago
The article doesn't make it clear how many such cases there are: > The South Korean figure had risen from 51 such cases on Monday. > "The number will only increase, 91 is just the beginning now"
merricksb 7y ago
Same topic discussed yesterday: https://news.ycombinator.com/item?id=22820421 https://news.ycombinator.com/item?id=22820421
robocat 7y ago
The issue is talked about at 7:59 in this video https://youtu.be/gAk7aX5hksU https://youtu.be/gAk7aX5hksU (Leading COVID-19 Expert Professor Kim Woo-joo from Korea University Guro Hospital)

58 points by abhiminator 7y ago

Do we have any data on South Korea's tests and their false positive/negative rates? Even a couple percent would lead to several cohorts of "tested positive but weren't" and "tested negative but still were actually positive", I'd think.

drocer88 7y ago

Key passage from the text: Kim also said patients had likely “relapsed” rather than been re-infected. False test results could also be at fault, other experts said, or remnants of the virus could still be in patients’ systems but not be infectious or of danger to the host or others. “There are different interpretations and many variables,” ...

_wldu 7y ago
Many of the COVID tests are not cleared/approved or even authorized for emergency use yet. But, this is what we are having to rely on to count confirmed cases due to the circumstances. https://www.questdiagnostics.com/dms/Documents/covid-19/SARSCoV-2_Patient_Fact_Sheet.pdf https://www.questdiagnostics.com/dms/Documents/covid-19/SARS... "Is this test FDA-approved or cleared? No. This test is not yet approved or cleared or authorized by the United States Food and Drug Administration (FDA). When there are no FDA-approved or cleared tests available, and other criteria are met, FDA can make tests available under an emergency access mechanism called an Emergency Use Authorization. Quest Diagnostics is working with FDA to obtain Emergency Use Authorization." And the tests that are authorized for emergency use are not FDA cleared or approved. "Testing was performed using the cobas(R) SARS-CoV-2 test. This test was developed and its performance characteristics determined by LabCorp Laboratories. This test has not been FDA cleared or approved. This test has been authorized by FDA under an Emergency Use Authorization (EUA). This test is only authorized for the duration of time the declaration that circumstances exist justifying the authorization of the emergency use of in vitro diagnostic tests for detection of SARS-CoV-2 virus and/or diagnosis of COVID-19 infection under section 564(b)(1) of the Act, 21 U.S.C. 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner."
- pmoriarty 7y ago
  On the subject of unreliable tests, here's a transcript of a letter read on episode 588 of This Week in Virology[1]: I'm an infectious disease doctor and would like to point out an important factor in diagnosing this infection (and all respiratory pathogens that use nucleic acid probes for specimen collection). This is of particular concern now that China has transitioned to a much more problematic clinical diagnosis based more on clinical symptoms than PCR testing. While it may seem trivial how a health care worker jams a swab in to someone's throat or nose, technique is important. If anterior naries (front of nose) swabs or side of mouth swabs are done, rather than the true posterior nasopharynx or oropharangeal swabs, the sensitivity drops dramatically. We have shown this to be true repeatedly with diagnosis of influenza and respiratory pathogens, and I am disappointed that it has not been mentioned more in discussions about the PCR tests, missing the diagnosis in people who are positive and negative then positive again. We often see people admitted from the ER with the perhaps carelessly collected flu test who miraculously are flu positive by the time they are admitted. Like so many cultures and diagnostics in infectious diseases, specimen collection and handling is critical. I warn my patients about the unpleasantness of a nasopharangeal swab and jokingly tell them that if it doesn't cause a wincy-face reaction we haven't collected specimens from where the viruses reside. [1] - http://www.microbe.tv/twiv/twiv-588/; http://www.microbe.tv/twiv/twiv-588/; at about 1 hour and 38 minutes in
  - macintux 7y ago
    I had one of those nasopharyngeal swab tests conducted about a month ago for the flu. It was extremely unpleasant, so I can concur with the good doctor, albeit astonishingly brief.
- icegreentea2 7y ago
  The EUA-ness of the test has very little to do with re-positives. RT-PCR tests can only test for the presence of viral RNA in the sample collected. They cannot tell you the viability of the viral particles, they cannot tell you if you going to get sicker, or going to get better the next day. We don't even fully understand the relationship between vRNA detection and contagiousness. And all of those unknowns are outside of the scope of the test. Even in normal times, these tests can only be used to determine if genetic material exists (and sometimes the quantity if the collection mechanism and processing are controlled enough). It must be left up to clinicians to interpret these results. The current protocol is to wait for 2 consecutive negatives 24 hours apart to call someone virus free. That's a protocol created by clinicians in a time of extreme pressure and need based on empirical measurements and prior body of knowledge. A 510k cleared COVID test would have most of the same issues because the problem isn't strictly that the tests can't reliability detect viral particles, the problem is that we don't know what actually constitutes "cured".
fmjrey 7y ago
A bogus test would explain a lot of oddities such as a high number of asymptomatic cases and testing positive again after recovery. It would help to know what is being tested exactly: are we sure we isolated that virus, how specific is the sequence being tested?

jliptzin 7y ago

Could this turn out like HIV where there is an initial infection period followed by some dormant period and then another period where it causes more problems for the host again?

SpicyLemonZest 7y ago
It's unlikely. Coronaviruses are well-known and well-studied, so we can be pretty confident that the disease will just be a single respiratory tract infection rather than anything weirder.
yyyk 7y ago
Possible but unlikely since this is an RNA virus (unlike HIV) which shouldn't be able to 'hibernate' in cell DNA. If it can still be dormant - where would it 'hide'?

jrockway 7y ago

What is our plan if Covid-19 doesn't go away after you recover from an infection?

snissn 7y ago
i think our plan would be to come up with a new plan
jdavis703 7y ago
Something like PREP (anti-HIV drug for people in high risk groups) probably. There also might be a lot of deaths and suffering if it takes a long time to create a coronavirus prophylaxis medicine.
12yrprogrammer 7y ago
No politician wants to say it, but the plan regardless was to quarentine until a vaccine comes out in 1 or 2 years. That or accept the 0.5 percent death rate with the "flatten the curve" method where we all catch it. Your concern means we'd only have situation 1, quarentine for 1 or 2 years.
- TaylorGood 7y ago
  Logic says this too. Deadly, contagious virus with no vaccine, which takes roughly 18 months. There aren't too many options. I've heard chatter that big co's started telling their employees they're planning 18 months WFH.
  - rpiguy 7y ago
    Logic says just to live with it like we live with the flu and go on with life. The mortality rate is comparable. CDC is projecting 60K deaths if we open up most of the economy by the end of May. In the 2018-2019 flu season flu killed 80,000. Once the disease surge in densely populated ends areas it appears to become quite manageable.
    - yyyk 7y ago

gnulinux 7y ago

Layman here. Curious: if this is true, that you don't gain long term immunity to SARS-2 by catching COVID, would that have any implications on potential vaccine in the future? Does this mean, this virus is something we cannot build a vaccine for? Does this mean even if we have an approved vaccine, it would likely have a very low probability to protect us? Or do RNA vaccines work in a way that affects our immune system that's entirely different than how immune system builds immunity against the virus itself?

ping_pong 7y ago
There was an experiment done a few weeks back where they infected rhesus monkeys with SARS-CoV-2 and the monkeys were subsequently immune. So the idea that we humans don't get some amount of immunity would be hard to believe. https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1 https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1

RyanShook 7y ago

Isn’t the concept of someone being reinfected with the exact same virus basically unheard of?

pcr0 7y ago
No, herpes, chickenpox + shingles would be the counter examples.
- nkohari 7y ago
  In my understanding, herpes and varicella (chicken pox/shingles) are thought to be "reactivations" of dormant viruses, not reinfections. The virus is never fully eliminated, and sometimes it becomes re-activated.
mythobit 7y ago
I'm not certain if you are talking specific to coronavirus, but it is not unheard of with viruses. For example, chickenpox/shingles or herpes.
throwaway5752 7y ago
We have coronaviruses. There is no "cold" virus really and it's an umbrella term for a few different viruses including coronaviruses. With human adapted coronaviruses - unlike zoonotic covid-19 - you don't get lifetime immunity https://www.ncbi.nlm.nih.gov/books/NBK7782/ https://www.ncbi.nlm.nih.gov/books/NBK7782/ You can just think of booster immunizations and getting tetanus shots when you're exposed. Why would you need those, otherwise? If you want to learn more looking into memory T and B cells.

Nav_Panel 7y ago

Where's the study and data? What's the time frame we're looking at here? This German study (https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v1 https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v... -- see the graphs near the end of the PDF) suggests that viral RNA may be detectable in recovered patients for 3 weeks after symptom onset, or longer (the study seemed to stop testing after 3 weeks, despite some recovered patients still testing positive for viral RNA). But they were unable to isolate live virus after about a week post-onset. Could this be what we're seeing? If you're still worried, I recommend looking at this small study on macaques designed to test immunity (https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1 https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1). They found that the macaques did develop immunity and were able to fight off the virus on reinfection. If we compare with the this study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/) on the development of immunity in response to the original SARS virus (I'm not sure on the exact mechanism of immunity, but if the body's immunoglobulin response targets the spike protein, then it's probably similar), we should probably expect antibody production to continue at least a year after infection, if not for 3-4 years after.

angel_j 7y ago

I feel like we're about to learn way more about viruses than we thought we knew. It's like how NYTimes "scientists" only recently learned that gut bacteria is our friend...

emersion 7y ago

The article doesn't make it clear how many such cases there are: > The South Korean figure had risen from 51 such cases on Monday. > "The number will only increase, 91 is just the beginning now"

merricksb 7y ago

Same topic discussed yesterday: https://news.ycombinator.com/item?id=22820421 https://news.ycombinator.com/item?id=22820421

robocat 7y ago

The issue is talked about at 7:59 in this video https://youtu.be/gAk7aX5hksU https://youtu.be/gAk7aX5hksU (Leading COVID-19 Expert Professor Kim Woo-joo from Korea University Guro Hospital)