19 ms·

Recovered virus patients retest positive due to 'dead' virus fragments: experts

237 points by lsllc 7y ago

war1025 7y ago
This is excellent news.
alejohausner 7y ago
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 7y ago
  In other words, when you recover from covid-19, you are immune to it How does this follow?
  - eloff 7y ago
    That's how immunity against pathogens usually works. There are exceptions like the flu which mutates into sufficiently distinct strains that the immune system doesn't (fully) recognize. I'm still oversimplifying here.
    - pbhjpbhj 7y ago
      Well viruses in general, AFAIK, mutate - and that's how we trace their movement through the infected: you sample the virus and look at the mutations eg https://nextstrain.org/ncov https://nextstrain.org/ncov. Do we know for sure that Covid19 in N.Europe isn't sufficiently mutated over that in Australia, say, that secondary infection is possible (even if recovered people's antibodies recognise it somewhat)?
      - eloff 7y ago
        We don't know much for sure. What I've heard from experts in the field, but I don't have sources, is that the type of RNA virus is different from influenza and doesn't mutate as quickly - which is potentially good news for those hoping for a vaccine.
  - AnimalMuppet 7y ago
    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 7y ago
      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 7y ago
        Is this a joke? Literally the article at the top.
        pbhjpbhj 7y ago
        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.
        thro1 7y ago
        He is right, people may be testing positive just because of dead virus fragments, but to say they have fully recovered there must be no virus alive in their bodies - lack of symptoms may suggest it, then having antibodies may guarantee that eventually.. .. assuming the virus can not hide (and be able to leave) where they can't penetrate - like in the eye ? .. and with weak immune system the outcome may be (how?)long undecided as the antibodies are not being able to fight the virus fast enough to finish it definitely?
  - jrockway 7y ago
    That doesn't strictly follow. Here is the thought process, though. Typically when you get an infection, your body builds antibodies that can attack the pathogen. The next time the pathogen shows up, your body kills it before you get sick. This immunity doesn't always last for a lifetime, but there is pretty much always some immunity. With COVID-19, early reports showed that this wasn't happening; people got sick, recovered, and then got COVID-19 again. What the news article says is that the test was wrong; when they tested positive the second time, the test was just returning incorrect results (because of limitations of the PCR technique; it's testing for certain RNA, not for the existence of an infectious live virus). So to say that this means you can be immune to SARS-CoV-2 is not strictly correct. What it says is that there is no reason to think that this virus is any different from many of the other viruses that we already know about. (We do know about viruses that you can't be immune to, like HIV. But those viruses explicitly attack the immune system machinery that is supposed to kill them. We have no evidence that SARS-CoV-2 does that.)
    - jtbayly 7y ago
      We also know that immunity to coronaviruses generally declines rapidly. We have no idea how long somebody is immune to Covid-19 when they have recovered.
  - rdiddly 7y ago
    It doesn't strictly follow, you're right. But this punches a huge hole in the already kind of surprising/unlikely possibility that we had suddenly just discovered the first (or if I'm wrong, "a very rare") virus that can re-infect the same person with the same strain.
  - eschutte2 7y ago
    In at least two ways I can think of. First, these fragments have been inactivated, probably by the immune system, suggesting you have some immunity (obviously, that's not the same as being perfectly immune). Second, given how infectious the virus is, the fact they're not finding genuine positive re-tests strongly suggests some immunity is happening.
  - umanwizard 7y ago
    How would you recover at all if your body weren't producing antibodies capable of killing it?
- twomoretime 7y ago
  >in other words, when you recover from covid-19, you are immune Well, it may appear to be the case so far but afaik that hasn't been rigorously confirmed, and this article doesn't imply immunity to live virus upon reexposure. >but that doesn't mean the virus is some sort of strange monster Except there are dozens of papers being publishes about a range of effects - damage to a multitude of organs, virus fragments found in brains during autopsy, high incidence of clotting/stroke. By many SME accounts it is very much a strange monster. Also recall the documented rapid progression from asymptomatic to dead. >It's extremely infectious, and somewhat more lethal than influenza So one of these numbers (CFR) is about the same, but the R0 is anywhere from 2-4 times larger, and the critical rate appears to much higher than the typical flu. So the response of "terror" isn't totally unwarranted. >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. Agreed. And another reinfection case occured in an immunocompromised patient. So it's looking like the infection doesn't become chronic or dormant.
- acqq 7y ago
  > somewhat more lethal than influenza My understanding is that most evidence points to order of magnitude more lethal even when the hospitals aren't overflown. Regarding "testing negative then positive" the experts already expected that there were no real reinfections.
  - throwaway894345 7y ago
    > My understanding is that most evidence points to order of magnitude more lethal even when the hospitals aren't overflown. If those mortality estimates were based on the number of positive test cases, then they're very likely overblown. Recent seralogical studies indicate that the number of positive test results are likely a small fraction of the total number of cases, and likely the most severe subset at that. None of this is to say that it's less lethal than influenza, only that the situation is developing rapidly and any given mortality estimate may well be outdated.
    - JoeAltmaier 7y ago
      In any case, we can all agree that regardless of the value of the number, its "way too many fatalities". My family has lost several colleagues/classmates already. This did not happen in other years. This year is very different, and concerning.
      - throwaway894345 7y ago
        I'm terribly sorry for your losses. It's an awful disease, and loss of life is terrible. It is indeed concerning, but if we can understand whether these fatalities are due to high morbidity or "simply" because it is highly contagious, we can make better decisions about treating the disease, setting policy, etc which can all drive down the amount of suffering and death. That's perhaps a small consolation to those who have lost friends and family already. :'(
    - rocha 7y ago
      My understanding is that the current estimated IFR from those studies (NY specially) is between 0.6% and 1.2%. I think flu is around 0.1% (however I am not sure if that is the CFR or the IFR). The second factor to consider is the attack rate, how many people are likely to get infected. For flu is around between 10% to 15% of the total population, while for Covid it is, potentially, larger than 80% (no natural immunity and no vaccines). It is however unlikely that it will reach that level given the current containment and mitigation measures. But if it reaches something like 40% (double of the latest NY estimate), it will mean covid is between 16 to 48 times deadlier than the flu.
- cpuguy83 7y ago
  Governments are reacting to a seemingly very high infection rate with a (best case from the numbers I've seen) fatality rate 10x higher than the flu and the inadequacy of healthcare systems to shoulder the burden all at once (which has more side effects, including more death).
- _bxg1 7y ago
  Correction: the virus isn't some sort of strange monster in this particular aspect. Have you seen the reports of blood-clotting problems? Sudden deaths from people who'd shown no symptoms? There's still a lot that's weird about this disease and we have a long way to go before we understand it.
  - TheBlight 7y ago
    I'd hold off banking too heavily on anecdotal data. That's how everyone got all worked up about this reinfection story a few weeks ago.
    - jonahbenton 7y ago
      With respect, the story of both governmental and private sector response to COVID has almost universally been not being worked up enough.
      - SpicyLemonZest 7y ago
        Surely the right response to that isn't to always be more worked up.
        felipemnoa 7y ago
        I think he means plan for the worst, hope for the best.
      - dekhn 7y ago
        From what I can tell, the governor in my state (CA) took an appropriate level of actions at roughly the right time (after realizing that the federal government declined to be useful). We appear to be passing through the first big wave of deaths, and cautiously reopening slowly. It's unclear what additional actions would have changed things (in terms of reducing total # of deaths, or any suffering while sick).
      - fuckknows 7y ago
        Sure, but by getting yourself worked up you're not improving that situation any.
- foxyv 7y ago
  Reinfection can occur with most viruses when a person is exposed too soon after the primary immune response. It takes a while for someone to develop full immunity after recovery. This happened with H1N1 for patients back in 2008. https://www.virology.ws/2009/12/28/reinfection-with-2009-influenza-h1n1/ https://www.virology.ws/2009/12/28/reinfection-with-2009-inf...
  - nfin 7y ago
    Are we talking 2 weeks, a month or 3 months, 6 months+?
  - mcbutterbunz 7y ago
    Does viral load also matter? I would imagine that getting hit with a high number of viruses shortly after recovery could cause some issues but I'm just an observer in all of this.
- throwaway894345 7y ago
  Seems like this would make serology tests a lot more useful. I would really like to know if I've had it so I can know how at-risk I am (and consequently the risk I pose to others).
- majormajor 7y ago
  > 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. "Every other virus" doesn't behave the same in this regard. The viruses that cause colds, many of which are also coronaviruses, are pretty adept at hitting people throughout their life. Hopefully it's not an issue here, but it's completely unsurprising that people would want to actually research it instead of just declaring all viruses are the same. The only fools here are the people whose impatience leads them to declare absolutes ahead of times instead of taking preventive measures while the research plays out. https://www.npr.org/sections/goatsandsoda/2020/03/20/819038431/do-you-get-immunity-after-recovering-from-a-case-of-coronavirus https://www.npr.org/sections/goatsandsoda/2020/03/20/8190384... > Researchers do know that reinfection is an issue with the four seasonal coronaviruses that cause about 10 to 30% of common colds.
  - deleted 7y ago
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  - f38zf5vdt 7y ago
    Yes. It's suspected that immunity is very short lived. > This study provides evidence that re-infections with the same endemic coronavirus are not atypical in a time window shorter than 1 year and that the genetic basis of innate immune response maybe a greater determinant of infection severity than immune memory acquired after a previous infection. http://www.columbia.edu/%7Ejls106/galanti_shaman_ms_supp.pdf http://www.columbia.edu/%7Ejls106/galanti_shaman_ms_supp.pdf Even if you recover, there's not a lot of evidence now as to what the duration of immunity will be. With this spreading through the world at different paces, it means that, as commonly predicted, we will see continuous re-emergence as we do with other cold viruses and influenza.
    - CyanLite2 7y ago
      Recovered patients from SARS-1 had long-term antibodies in good concentrations until about 3 years after the infection. We can expect about the same since both coronaviruses are so similar. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/
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- rocha 7y ago
  Note that the immunity is not permanent. The average immunity to the endemic coronaviruses that cause the common cold lasts about a year.
  - fat_turdsicle 7y ago
    Could you provide a source? Happen to be studying this topic for a paper I'm writing
    - rocha 7y ago
      Sure: https://www.technologyreview.com/2020/04/27/1000569/how-long-are-people-immune-to-covid-19/ https://www.technologyreview.com/2020/04/27/1000569/how-long...
- tptacek 7y ago
  In the interpretation of the NYS serostudy most favorable to your argument (assume perfect specificity), with 21% actually infected in NYC proper, based on the death statistics and the population of NYC, C19 appears to be a full order of magnitude more lethal than any recent flu strain. That's more than "somewhat" more lethal. Putting this into perspective: in roughly a single month, we've already doubled the 7-year average annual number of flu deaths. Project those C19 stats out across the whole population, and assume (generously) herd immunity effects at 70% that halt the progression, and you're looking at mortality rate that swamps that of all wars, terrorist attacks, and natural disasters faced by the US for the last 50 years, right? Put differently, unchecked and with that extrapolated fatality rate, we'd be looking at something like 53 years worth of flu deaths at the average annual flu death rate? (Again, I'm just averaging the last 7 years for which we have flu stats; they range between ~12k-45k.) (Happy to have my math corrected).
  - TheGallopedHigh 7y ago
    This idea of putting 50 years of any war/ attacks etc is misguided and it’s a wrong use of statistics. A better approach would be to take into account other diseases as you have with its close relative the flu. Others on the list would be other types of diseases. Because all of those dwarfs numbers from wars etc.
    - tptacek 7y ago
      Why is it "misguided and a wrong use of statistics"? It's true that the flu kills far more Americans than the last 50 years of war has. If a new disease emerged that was just the flu in a different form, and we retained the mortality rates both from the flu and that new disease, that alone would be extremely alarming: a new cause of death, displacing none of the other deaths, that exceeds most other causes! Honestly, I think we don't do nearly enough comparisons between disease mortality and other causes of mortality. A "War On Cancer" would have done us far more good than the wars we declared in the 2000s would have.
      - alejohausner 7y ago
- Leary 7y ago
  There have also been cases where people looked like they've recovered, tested negative, and then became ill again after 2 weeks and tested positive again. I always suspected those were mostly due to false negatives from PCR tests. Probably only a tiny minority of people had not enough immune response for them to become reinfected.
  - Marsymars 7y ago
    Given a large enough sample size, you're also going to get people who recover, test negative due to a false negative, then get influenza two weeks later, then test positive due to dead SARS-COV-2 RNA. And various other edge case permutations like that.
- staticassertion 7y ago
  Virtually all messaging I've seen has been "We lack evidence to say how immunity works" with a dose of "there's some initial evidence suggesting immunity" and "we aren't sure about how long it lasts". It's interesting to read "it's extremely infectious" and "more lethal than influenza" followed by "that's all", not to mention the missing bit about not having a vaccine! If we saw a massive outbreak of influenza things would be extremely different. We have treatments for influenza (tamiflu), we have vaccines, we have understanding, and a large portion of the population that is already immune. The similarities are... they are both viruses. Not sure why anyone would compare the two except to try to explain how different they are.
- draw_down 7y ago
  Everyone's an armchair virologist all of a sudden in this crisis. Heartening to find we had such expertise just lying around, waiting!
- dekhn 7y ago
  I don't think we have any reliable evidence of post-recovery immunity at all. I wouldn't expect to have any until we've seen multiple cycles of this virus, and analyzed the data carefully. Press-release-science during an emergency is close to worthless.
  - rootusrootus 7y ago
    If you don't have any post-recovery immunity, then how do you ever recover to begin with?
    - dekhn 7y ago
      immunity prevents you from being infected, not from eliminating the virus. People who are cured of AIDS by eliminating HIV aren't then immune.
      - rootusrootus 7y ago
        HIV is a bit of a special case to begin with, since it's attacking the very immune system that would try to kill it. But is anyone clearing the virus on their own? I thought it required extensive retroviral therapy, and even then it isn't actually cleared? Admittedly, I don't really keep up on the status of HIV, maybe something has changed.
        dekhn 7y ago
        A very small number of people have natural immunity. https://en.wikipedia.org/wiki/Innate_resistance_to_HIV https://en.wikipedia.org/wiki/Innate_resistance_to_HIV I am not sure if anybody gets infected, then clears the virus on their own.
- aaomidi 7y ago
  Sigh. I was waiting for the "Govts have overreacted" message. This is a ridiculous criticism to have to the response to this pandemic. We NEED to overreact so we don't underreact.
- p49k 7y ago
  > 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. That’s not how HSV works. That’s not how hepatitis works.
  - mirthflat83 7y ago
    “Just like other coronaviruses” There you go
    - p49k 7y ago
      Even that's not true. 15-30% of the viruses that are attributed to the common cold are coronaviruses, and it's pretty clear that the common cold does not behave in the way OP described.
      - mirthflat83 7y ago
        Do you know about genetic drift/shift/different strains? Moreover, recent literature continues to confirm that you have protective immunity after recovering from covid like any other coronavirus. This is the basis for convalescent plasma therapy
        p49k 7y ago
        Yes, but you’re drifting from the original point I was arguing against: “all viruses act exactly like the flu, therefore governments overreacted by not immediately assuming it was exactly like the flu” - which has a false premise.
        mirthflat83 7y ago
        No, it’s you who’s drifting away from “Just like other coronaviruses”
  - mr_toad 7y ago
    You don’t get re-infected by HSV or chronic hepatitis; you don’t recover in the first place. In the first case the virus hides from the immune system, in the second it never properly overcomes the infection.
- deleted 7y ago
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- throwawaymanbot 7y ago
  I believe they authors said "May" in this. Not that this is 100% the cause. Political tinged screeds are not really appropriate for this issue.
- takecarefnd 7y ago
  in the article it didn't mention whether when you recover from covid-19, you are immune to it.
- thro1 7y ago
  > In other words .. What you write is disconnected from the article, immunity was discussed more deeply elsewhere on HN already.
- ridgeguy 7y ago
  >In other words, when you recover from covid-19, you are immune to it. Probably not. It seems [1] that in humans and animals, there's no long-term immunity arising from infection. [1] https://www.quantamagazine.org/what-can-other-coronaviruses-tell-us-about-sars-cov-2-20200429/ https://www.quantamagazine.org/what-can-other-coronaviruses-...
- scotty79 7y ago
  > In other words, when you recover from covid-19, you are immune to it. At least for some time. > In other words, covid-19 is just like every other virus, in this respect. Other coronaviruses don't mutate, yet reinfect lots of people and cause some common cold roughly every two years. I think we can expect roughly the same from covid19. Peak every two years until we have a vaccine. Then annual covid19 vaccine shot to refresh the immunity.
lend000 7y ago
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 7y ago
  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 7y ago
    If it started in December, it's probably not covid 19. If you don't have a fever, it's probably not covid 19.
    - tonyedgecombe 7y ago
      I saw a report today that said most people going to hospital with covid-19 don't have a fever.
    - Izkata 7y ago
      The official record has traced the first case back to November 17, so it definitely seems at least possible it was spreading earlier than we know.
    - GenerocUsername 7y ago
      2020, the year COVID outranks Cancer as the webs goto diagnosis for anything and everything
econcon 7y ago
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 7y ago
  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.
  - econcon 7y ago
    Not always immune system can recognize fragment of a virus as threat even if it was battling the very same virus before.
  - clairity 7y ago
    it's not even that viruses don't work that way, entropy doesn't work that way.
    - greenshackle2 7y ago
      You mean you don't assemble Lego models by putting all the pieces in a box and vigorously shaking it?
      - quxbar 7y ago
        I have an infinite team of monkeys working on it...
        prox 7y ago
        That is what my Boltzmann brain just told me
TheBlight 7y ago
I wonder if this gets the CNN headline treatment like the original story did...
doctoring 7y ago
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 7y ago
  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/10.1101/2020.03.05.20030502v1 https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v... 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.
abracada_toss 7y ago
good news ... i think then vaccine will work?
kragen 7y ago
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 7y ago
  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 7y ago
    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.
yters 7y ago
So once we develop a covid-19 vaccine and immunize a bunch of people, will we suddenly have a relapse of people testing positive for covid-19? Will deaths due to pneumonia and other respiratory problems get attributed to covid-19 because of the vaccine? Will we go into another lockdown after the vaccination?
- ceejayoz 7y ago
  No, no, and only if the vaccine is ineffective.
  - yters 7y ago
    Why wouldn't deaths be attributed to covid-19 if patient tests positive and has the symptoms?
    - ceejayoz 7y ago
      1. By the time we have a vaccine, we'll have the capacity to test deceased patients, rather than having to presume based on pre-death symptoms. 2. We'll know when someone was vaccinated, and how long it takes for someone to test negative again after having received one. We won't be using antibody tests on someone who's had the vaccine, as it'd be silly.
simonsarris 7y ago
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.
a3n 7y ago
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?
- grandmczeb 7y ago
  The fragments are inactive so no.
- CyanLite2 7y ago
  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.
tunesmith 7y ago
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 7y ago
  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 7y ago
    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 7y ago
      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.
paypalcust83 7y ago
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 7y ago
  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.
rurban 7y ago
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.

237 points by lsllc 7y ago

This is excellent news.

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 7y ago
In other words, when you recover from covid-19, you are immune to it How does this follow?
- eloff 7y ago
  That's how immunity against pathogens usually works. There are exceptions like the flu which mutates into sufficiently distinct strains that the immune system doesn't (fully) recognize. I'm still oversimplifying here.
  - pbhjpbhj 7y ago
    Well viruses in general, AFAIK, mutate - and that's how we trace their movement through the infected: you sample the virus and look at the mutations eg https://nextstrain.org/ncov https://nextstrain.org/ncov. Do we know for sure that Covid19 in N.Europe isn't sufficiently mutated over that in Australia, say, that secondary infection is possible (even if recovered people's antibodies recognise it somewhat)?
    - eloff 7y ago
      We don't know much for sure. What I've heard from experts in the field, but I don't have sources, is that the type of RNA virus is different from influenza and doesn't mutate as quickly - which is potentially good news for those hoping for a vaccine.
- AnimalMuppet 7y ago
  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 7y ago
    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 7y ago
      Is this a joke? Literally the article at the top.
      - pbhjpbhj 7y ago
        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.
      - thro1 7y ago
        He is right, people may be testing positive just because of dead virus fragments, but to say they have fully recovered there must be no virus alive in their bodies - lack of symptoms may suggest it, then having antibodies may guarantee that eventually.. .. assuming the virus can not hide (and be able to leave) where they can't penetrate - like in the eye ? .. and with weak immune system the outcome may be (how?)long undecided as the antibodies are not being able to fight the virus fast enough to finish it definitely?
- jrockway 7y ago
  That doesn't strictly follow. Here is the thought process, though. Typically when you get an infection, your body builds antibodies that can attack the pathogen. The next time the pathogen shows up, your body kills it before you get sick. This immunity doesn't always last for a lifetime, but there is pretty much always some immunity. With COVID-19, early reports showed that this wasn't happening; people got sick, recovered, and then got COVID-19 again. What the news article says is that the test was wrong; when they tested positive the second time, the test was just returning incorrect results (because of limitations of the PCR technique; it's testing for certain RNA, not for the existence of an infectious live virus). So to say that this means you can be immune to SARS-CoV-2 is not strictly correct. What it says is that there is no reason to think that this virus is any different from many of the other viruses that we already know about. (We do know about viruses that you can't be immune to, like HIV. But those viruses explicitly attack the immune system machinery that is supposed to kill them. We have no evidence that SARS-CoV-2 does that.)
  - jtbayly 7y ago
    We also know that immunity to coronaviruses generally declines rapidly. We have no idea how long somebody is immune to Covid-19 when they have recovered.
- rdiddly 7y ago
  It doesn't strictly follow, you're right. But this punches a huge hole in the already kind of surprising/unlikely possibility that we had suddenly just discovered the first (or if I'm wrong, "a very rare") virus that can re-infect the same person with the same strain.
- eschutte2 7y ago
  In at least two ways I can think of. First, these fragments have been inactivated, probably by the immune system, suggesting you have some immunity (obviously, that's not the same as being perfectly immune). Second, given how infectious the virus is, the fact they're not finding genuine positive re-tests strongly suggests some immunity is happening.
- umanwizard 7y ago
  How would you recover at all if your body weren't producing antibodies capable of killing it?
twomoretime 7y ago
>in other words, when you recover from covid-19, you are immune Well, it may appear to be the case so far but afaik that hasn't been rigorously confirmed, and this article doesn't imply immunity to live virus upon reexposure. >but that doesn't mean the virus is some sort of strange monster Except there are dozens of papers being publishes about a range of effects - damage to a multitude of organs, virus fragments found in brains during autopsy, high incidence of clotting/stroke. By many SME accounts it is very much a strange monster. Also recall the documented rapid progression from asymptomatic to dead. >It's extremely infectious, and somewhat more lethal than influenza So one of these numbers (CFR) is about the same, but the R0 is anywhere from 2-4 times larger, and the critical rate appears to much higher than the typical flu. So the response of "terror" isn't totally unwarranted. >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. Agreed. And another reinfection case occured in an immunocompromised patient. So it's looking like the infection doesn't become chronic or dormant.
acqq 7y ago
> somewhat more lethal than influenza My understanding is that most evidence points to order of magnitude more lethal even when the hospitals aren't overflown. Regarding "testing negative then positive" the experts already expected that there were no real reinfections.
- throwaway894345 7y ago
  > My understanding is that most evidence points to order of magnitude more lethal even when the hospitals aren't overflown. If those mortality estimates were based on the number of positive test cases, then they're very likely overblown. Recent seralogical studies indicate that the number of positive test results are likely a small fraction of the total number of cases, and likely the most severe subset at that. None of this is to say that it's less lethal than influenza, only that the situation is developing rapidly and any given mortality estimate may well be outdated.
  - JoeAltmaier 7y ago
    In any case, we can all agree that regardless of the value of the number, its "way too many fatalities". My family has lost several colleagues/classmates already. This did not happen in other years. This year is very different, and concerning.
    - throwaway894345 7y ago
      I'm terribly sorry for your losses. It's an awful disease, and loss of life is terrible. It is indeed concerning, but if we can understand whether these fatalities are due to high morbidity or "simply" because it is highly contagious, we can make better decisions about treating the disease, setting policy, etc which can all drive down the amount of suffering and death. That's perhaps a small consolation to those who have lost friends and family already. :'(
  - rocha 7y ago
    My understanding is that the current estimated IFR from those studies (NY specially) is between 0.6% and 1.2%. I think flu is around 0.1% (however I am not sure if that is the CFR or the IFR). The second factor to consider is the attack rate, how many people are likely to get infected. For flu is around between 10% to 15% of the total population, while for Covid it is, potentially, larger than 80% (no natural immunity and no vaccines). It is however unlikely that it will reach that level given the current containment and mitigation measures. But if it reaches something like 40% (double of the latest NY estimate), it will mean covid is between 16 to 48 times deadlier than the flu.
cpuguy83 7y ago
Governments are reacting to a seemingly very high infection rate with a (best case from the numbers I've seen) fatality rate 10x higher than the flu and the inadequacy of healthcare systems to shoulder the burden all at once (which has more side effects, including more death).
_bxg1 7y ago
Correction: the virus isn't some sort of strange monster in this particular aspect. Have you seen the reports of blood-clotting problems? Sudden deaths from people who'd shown no symptoms? There's still a lot that's weird about this disease and we have a long way to go before we understand it.
- TheBlight 7y ago
  I'd hold off banking too heavily on anecdotal data. That's how everyone got all worked up about this reinfection story a few weeks ago.
  - jonahbenton 7y ago
    With respect, the story of both governmental and private sector response to COVID has almost universally been not being worked up enough.
    - SpicyLemonZest 7y ago
      Surely the right response to that isn't to always be more worked up.
      - felipemnoa 7y ago
        I think he means plan for the worst, hope for the best.
    - dekhn 7y ago
      From what I can tell, the governor in my state (CA) took an appropriate level of actions at roughly the right time (after realizing that the federal government declined to be useful). We appear to be passing through the first big wave of deaths, and cautiously reopening slowly. It's unclear what additional actions would have changed things (in terms of reducing total # of deaths, or any suffering while sick).
    - fuckknows 7y ago
      Sure, but by getting yourself worked up you're not improving that situation any.
foxyv 7y ago
Reinfection can occur with most viruses when a person is exposed too soon after the primary immune response. It takes a while for someone to develop full immunity after recovery. This happened with H1N1 for patients back in 2008. https://www.virology.ws/2009/12/28/reinfection-with-2009-influenza-h1n1/ https://www.virology.ws/2009/12/28/reinfection-with-2009-inf...
- nfin 7y ago
  Are we talking 2 weeks, a month or 3 months, 6 months+?
- mcbutterbunz 7y ago
  Does viral load also matter? I would imagine that getting hit with a high number of viruses shortly after recovery could cause some issues but I'm just an observer in all of this.
throwaway894345 7y ago
Seems like this would make serology tests a lot more useful. I would really like to know if I've had it so I can know how at-risk I am (and consequently the risk I pose to others).
majormajor 7y ago
> 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. "Every other virus" doesn't behave the same in this regard. The viruses that cause colds, many of which are also coronaviruses, are pretty adept at hitting people throughout their life. Hopefully it's not an issue here, but it's completely unsurprising that people would want to actually research it instead of just declaring all viruses are the same. The only fools here are the people whose impatience leads them to declare absolutes ahead of times instead of taking preventive measures while the research plays out. https://www.npr.org/sections/goatsandsoda/2020/03/20/819038431/do-you-get-immunity-after-recovering-from-a-case-of-coronavirus https://www.npr.org/sections/goatsandsoda/2020/03/20/8190384... > Researchers do know that reinfection is an issue with the four seasonal coronaviruses that cause about 10 to 30% of common colds.
- deleted 7y ago
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- f38zf5vdt 7y ago
  Yes. It's suspected that immunity is very short lived. > This study provides evidence that re-infections with the same endemic coronavirus are not atypical in a time window shorter than 1 year and that the genetic basis of innate immune response maybe a greater determinant of infection severity than immune memory acquired after a previous infection. http://www.columbia.edu/%7Ejls106/galanti_shaman_ms_supp.pdf http://www.columbia.edu/%7Ejls106/galanti_shaman_ms_supp.pdf Even if you recover, there's not a lot of evidence now as to what the duration of immunity will be. With this spreading through the world at different paces, it means that, as commonly predicted, we will see continuous re-emergence as we do with other cold viruses and influenza.
  - CyanLite2 7y ago
    Recovered patients from SARS-1 had long-term antibodies in good concentrations until about 3 years after the infection. We can expect about the same since both coronaviruses are so similar. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/
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rocha 7y ago
Note that the immunity is not permanent. The average immunity to the endemic coronaviruses that cause the common cold lasts about a year.
- fat_turdsicle 7y ago
  Could you provide a source? Happen to be studying this topic for a paper I'm writing
  - rocha 7y ago
    Sure: https://www.technologyreview.com/2020/04/27/1000569/how-long-are-people-immune-to-covid-19/ https://www.technologyreview.com/2020/04/27/1000569/how-long...
tptacek 7y ago
In the interpretation of the NYS serostudy most favorable to your argument (assume perfect specificity), with 21% actually infected in NYC proper, based on the death statistics and the population of NYC, C19 appears to be a full order of magnitude more lethal than any recent flu strain. That's more than "somewhat" more lethal. Putting this into perspective: in roughly a single month, we've already doubled the 7-year average annual number of flu deaths. Project those C19 stats out across the whole population, and assume (generously) herd immunity effects at 70% that halt the progression, and you're looking at mortality rate that swamps that of all wars, terrorist attacks, and natural disasters faced by the US for the last 50 years, right? Put differently, unchecked and with that extrapolated fatality rate, we'd be looking at something like 53 years worth of flu deaths at the average annual flu death rate? (Again, I'm just averaging the last 7 years for which we have flu stats; they range between ~12k-45k.) (Happy to have my math corrected).
- TheGallopedHigh 7y ago
  This idea of putting 50 years of any war/ attacks etc is misguided and it’s a wrong use of statistics. A better approach would be to take into account other diseases as you have with its close relative the flu. Others on the list would be other types of diseases. Because all of those dwarfs numbers from wars etc.
  - tptacek 7y ago
    Why is it "misguided and a wrong use of statistics"? It's true that the flu kills far more Americans than the last 50 years of war has. If a new disease emerged that was just the flu in a different form, and we retained the mortality rates both from the flu and that new disease, that alone would be extremely alarming: a new cause of death, displacing none of the other deaths, that exceeds most other causes! Honestly, I think we don't do nearly enough comparisons between disease mortality and other causes of mortality. A "War On Cancer" would have done us far more good than the wars we declared in the 2000s would have.
    - alejohausner 7y ago
Leary 7y ago
There have also been cases where people looked like they've recovered, tested negative, and then became ill again after 2 weeks and tested positive again. I always suspected those were mostly due to false negatives from PCR tests. Probably only a tiny minority of people had not enough immune response for them to become reinfected.
- Marsymars 7y ago
  Given a large enough sample size, you're also going to get people who recover, test negative due to a false negative, then get influenza two weeks later, then test positive due to dead SARS-COV-2 RNA. And various other edge case permutations like that.
staticassertion 7y ago
Virtually all messaging I've seen has been "We lack evidence to say how immunity works" with a dose of "there's some initial evidence suggesting immunity" and "we aren't sure about how long it lasts". It's interesting to read "it's extremely infectious" and "more lethal than influenza" followed by "that's all", not to mention the missing bit about not having a vaccine! If we saw a massive outbreak of influenza things would be extremely different. We have treatments for influenza (tamiflu), we have vaccines, we have understanding, and a large portion of the population that is already immune. The similarities are... they are both viruses. Not sure why anyone would compare the two except to try to explain how different they are.
draw_down 7y ago
Everyone's an armchair virologist all of a sudden in this crisis. Heartening to find we had such expertise just lying around, waiting!
dekhn 7y ago
I don't think we have any reliable evidence of post-recovery immunity at all. I wouldn't expect to have any until we've seen multiple cycles of this virus, and analyzed the data carefully. Press-release-science during an emergency is close to worthless.
- rootusrootus 7y ago
  If you don't have any post-recovery immunity, then how do you ever recover to begin with?
  - dekhn 7y ago
    immunity prevents you from being infected, not from eliminating the virus. People who are cured of AIDS by eliminating HIV aren't then immune.
    - rootusrootus 7y ago
      HIV is a bit of a special case to begin with, since it's attacking the very immune system that would try to kill it. But is anyone clearing the virus on their own? I thought it required extensive retroviral therapy, and even then it isn't actually cleared? Admittedly, I don't really keep up on the status of HIV, maybe something has changed.
      - dekhn 7y ago
        A very small number of people have natural immunity. https://en.wikipedia.org/wiki/Innate_resistance_to_HIV https://en.wikipedia.org/wiki/Innate_resistance_to_HIV I am not sure if anybody gets infected, then clears the virus on their own.
aaomidi 7y ago
Sigh. I was waiting for the "Govts have overreacted" message. This is a ridiculous criticism to have to the response to this pandemic. We NEED to overreact so we don't underreact.
p49k 7y ago
> 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. That’s not how HSV works. That’s not how hepatitis works.
- mirthflat83 7y ago
  “Just like other coronaviruses” There you go
  - p49k 7y ago
    Even that's not true. 15-30% of the viruses that are attributed to the common cold are coronaviruses, and it's pretty clear that the common cold does not behave in the way OP described.
    - mirthflat83 7y ago
      Do you know about genetic drift/shift/different strains? Moreover, recent literature continues to confirm that you have protective immunity after recovering from covid like any other coronavirus. This is the basis for convalescent plasma therapy
      - p49k 7y ago
        Yes, but you’re drifting from the original point I was arguing against: “all viruses act exactly like the flu, therefore governments overreacted by not immediately assuming it was exactly like the flu” - which has a false premise.
        mirthflat83 7y ago
        No, it’s you who’s drifting away from “Just like other coronaviruses”
- mr_toad 7y ago
  You don’t get re-infected by HSV or chronic hepatitis; you don’t recover in the first place. In the first case the virus hides from the immune system, in the second it never properly overcomes the infection.
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throwawaymanbot 7y ago
I believe they authors said "May" in this. Not that this is 100% the cause. Political tinged screeds are not really appropriate for this issue.
takecarefnd 7y ago
in the article it didn't mention whether when you recover from covid-19, you are immune to it.
thro1 7y ago
> In other words .. What you write is disconnected from the article, immunity was discussed more deeply elsewhere on HN already.
ridgeguy 7y ago
>In other words, when you recover from covid-19, you are immune to it. Probably not. It seems [1] that in humans and animals, there's no long-term immunity arising from infection. [1] https://www.quantamagazine.org/what-can-other-coronaviruses-tell-us-about-sars-cov-2-20200429/ https://www.quantamagazine.org/what-can-other-coronaviruses-...
scotty79 7y ago
> In other words, when you recover from covid-19, you are immune to it. At least for some time. > In other words, covid-19 is just like every other virus, in this respect. Other coronaviruses don't mutate, yet reinfect lots of people and cause some common cold roughly every two years. I think we can expect roughly the same from covid19. Peak every two years until we have a vaccine. Then annual covid19 vaccine shot to refresh the immunity.

lend000 7y ago

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 7y ago
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 7y ago
  If it started in December, it's probably not covid 19. If you don't have a fever, it's probably not covid 19.
  - tonyedgecombe 7y ago
    I saw a report today that said most people going to hospital with covid-19 don't have a fever.
  - Izkata 7y ago
    The official record has traced the first case back to November 17, so it definitely seems at least possible it was spreading earlier than we know.
  - GenerocUsername 7y ago
    2020, the year COVID outranks Cancer as the webs goto diagnosis for anything and everything

econcon 7y ago

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 7y ago
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.
- econcon 7y ago
  Not always immune system can recognize fragment of a virus as threat even if it was battling the very same virus before.
- clairity 7y ago
  it's not even that viruses don't work that way, entropy doesn't work that way.
  - greenshackle2 7y ago
    You mean you don't assemble Lego models by putting all the pieces in a box and vigorously shaking it?
    - quxbar 7y ago
      I have an infinite team of monkeys working on it...
      - prox 7y ago
        That is what my Boltzmann brain just told me

TheBlight 7y ago

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

doctoring 7y ago

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 7y ago
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/10.1101/2020.03.05.20030502v1 https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v... 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.

abracada_toss 7y ago

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

kragen 7y ago

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 7y ago
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 7y ago
  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.

yters 7y ago

So once we develop a covid-19 vaccine and immunize a bunch of people, will we suddenly have a relapse of people testing positive for covid-19? Will deaths due to pneumonia and other respiratory problems get attributed to covid-19 because of the vaccine? Will we go into another lockdown after the vaccination?

ceejayoz 7y ago
No, no, and only if the vaccine is ineffective.
- yters 7y ago
  Why wouldn't deaths be attributed to covid-19 if patient tests positive and has the symptoms?
  - ceejayoz 7y ago
    1. By the time we have a vaccine, we'll have the capacity to test deceased patients, rather than having to presume based on pre-death symptoms. 2. We'll know when someone was vaccinated, and how long it takes for someone to test negative again after having received one. We won't be using antibody tests on someone who's had the vaccine, as it'd be silly.

simonsarris 7y ago

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.

a3n 7y ago

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?

grandmczeb 7y ago
The fragments are inactive so no.
CyanLite2 7y ago
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.

tunesmith 7y ago

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 7y ago
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 7y ago
  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 7y ago
    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.

paypalcust83 7y ago

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 7y ago
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.

rurban 7y ago

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.