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Japanese man tests positive for coronavirus again

134 points by koolba 7y ago

jrockway 7y ago
I was under the impression that one typically becomes immune to diseases like this, but apparently that's not the case? Does anyone have any reliable information here? Is this particular instance what we would typically expect, or can it be explained by test inaccuracy, something unusual about this person, etc.?
- kalium_xyz 7y ago
  Immunity seems to last only for a short period (few months) but there is not enough evidence to conclude anything yet really. This man might just not have recovered entirely at all though.
- deleted 7y ago
  [deleted]
- gvjddbnvdrbv 7y ago
  The Chinese say their are two distinct strains in circulation. Tests are not perfect. Plenty of explanations. Most of them quite uncomfortable.
  - jeltz 7y ago
    Do you have a source for that? Because the does not really match my reading of the data on https://nextstrain.org/ncov https://nextstrain.org/ncov.
    - barkerja 7y ago
      https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540747/all/Coronavirus_COVID_19__SARS_CoV_2_ https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX... > Preliminary evidence suggests two strains of SARS-2-CoV circulating: one associated with milder illness (~30%), the other with severe illness (70%).
  - pmoriarty 7y ago
    "The Chinese say their are two distinct strains in circulation." This has been debunked on This Week in Virology[1]: Vincent Racaniello: There are a series of articles here, where there have been some claims about different circulating lineages and what that means. Are you on this, Cathy? Cathy Spindler: Right. So, there was an article that I first saw in the LA Times "Chinese Scientists Say Second Coronavirus Strain Is More Dangerous"[2]. But in that there's a link to virological.org, which we talked about another article posted there a couple of weeks ago[3], and they really debunk this and think even that this Chinese article about a second Coronavirus should be retracted. Two of the key claims that are reached by misunderstanding and overinterpreation of data and an additional analysis suffers from methodological limitations. So this long thing on virological.org goes in to the reasons why there's no real evidence for two different strains, a more severe strain and a less severe strain. Rich Condit: It also provides a nice summary of this sort of variation in sequence that's being observed in the virus over time, which is good. Vincent: Yeah, it's a good aritcle. We'll put a link. It's worth reading, but as everyone should know, when these [indistinct] viruses, every replication cycle they sustain mutations in their genomes and the lethal ones are gone, the viruses don't reproduce, but some of them stay and if they're neutral they remain. So they can be characteristic. So the virus introduced in to the Washington area is a single introduction and then it's spread and you can tell that because it has a unique set of mutations compared to say, the Chinese isolate, but it doesn't mean anything biologically. It's just markers. Rich: And the markers are really interesting because they give you insight in to, I mean the insight that I got from observing what came out of the Washington cases is that from looking at the sequence of the virus they concluded that in fact it had been circulating for some time, and they could even get a very very rough estimate of how many cases might be out there based on the variation in sequence and the time at which the disease first showed up in a person. Vincent: I think there are some emails later about this. People are concerned that, and people suggest in these papers, at least the one here, that we're being critical of that it could be evolved to be more virulent or more transmissible. There's no evidence for that whatsoever. Rich: This is the kind of thing that... it just won't go away! Vincent: Oh, it doesn't go away... new outbreak and it comes back. Rich: Yeah, and there's no evidence. People have looked at this. We've gone over this for several.. Zika, Ebola, where's there's been variation and people point to a particular variation and they say, "This is going to make it more virulent" or something, and then the experiments ultimately get done and no. It hasn't made a difference. Vincent: And also the issue of increased transmissibility, I think this virus is already very transmissible as it is, and I think the mutations that made it effectively transmissible among humans, which happened very early on, I don't know, either in animals or in humans early on, before we knew about it, they're done, and it's going to be hard to know what they were. MERS coronavirus has never acquired those high transmissibility changes and it keeps fizzling out and then you have another reintroduction from camels but this particular SARS-Cov-2 sustained them probably early on and it's a very good transmitter. It doesn't need to get better, at least from my anthropocentric view. We never really know what viruses are selected by, but I don't think there's eny evidence, and it's very hard to get that evidence. That paper tells you what you need to prove that mutations are doing something phenotypically. It's very hard to get that. Rich: It has occurred to me that people who don't think about this stuff every day might be a little confused by this discussion relative to the discussion that goes on all the time about variation in influenza virus strains, and new strains coming up and having to change the vaccine and stuff. But that's different. That's variation in the influenza virus that makes it evade the existing immunity, and those sorts of variations arise so you get circulation of viruses that you don't have as good an immune response to, but that's different than a virus making mutations that make it more virulent. It's a different story. [1] - at about 13 minutes in to episode 590 - http://www.microbe.tv/twiv/twiv-590/ http://www.microbe.tv/twiv/twiv-590/ [2] - https://www.latimes.com/science/story/2020-03-05/chinese-scientists-say-second-coronavirus-strain-more-dangerous https://www.latimes.com/science/story/2020-03-05/chinese-sci... [3] - http://virological.org/t/response-to-on-the-origin-and-continuing-evolution-of-sars-cov-2/418 http://virological.org/t/response-to-on-the-origin-and-conti...
- alpaca128 7y ago
  Apparently in the case of viral infections it is normal to still be tested positive for some time after recovery, up to a few weeks. Unless there is really a confirmation of symptoms reappearing etc. I think this is the most plausible explanation.
- Tyr42 7y ago
  I know it's possible to have an issue with your immune system not storing the antibodies after fighting off a virus, so you can catch it again. But it's pretty rare?
- kzrdude 7y ago
  This is just one example, what conclusions can we draw from just that one?
- stevenwoo 7y ago
  Different corona viruses show different immunity periods after infection. The common cold is one that gives immunity of about a year after infection. We don't know how long immunity will last with covid-19.
geocrasher 7y ago
Edit: Is this lousy testing? Or mutation? It'll be interesting to see how this develops.
gnfisher 7y ago
It is unclear if he was symptomatic in the first positive test. I have read at least some of the tests are capable of giving false positives. Could this have been the case here?
- learc83 7y ago
  It's more likely that the tests that cleared him were false negatives.
  - baxtr 7y ago
    I understand that false negative PCR tests are almost impossible? EDIT: for those down voting. What about this paper then? https://pubmed.ncbi.nlm.nih.gov/32133832/ https://pubmed.ncbi.nlm.nih.gov/32133832/
    - snowmaker 7y ago
      It's the opposite. The PCR tests are more specific (99%) than sensitive (perhaps 90%, we're not really sure).
    - jennyyang 7y ago
      30% chance of false negative which is why they do 2 days in a row, which bring it down to 9% chance of false negatives.
      - PeterisP 7y ago
        Sooo, if you release a thousand patients as cured based on these tests, you'll have 90 false negatives...
    - deleted 7y ago
      [deleted]
    - ohazi 7y ago
      I think you have that backwards. False negative seems extremely plausible. If you're sick, but your viral load is low, it should be possible to collect a sample without a virus particle. If the sample doesn't contain a viral particle, it will necessarily come back negative. False positive seems unlikely, as you'd have to have something that survives several cloning cycles that ends up looking exactly like the markers you're matching against.
standardUser 7y ago
What has caused the slow rate of transmission in Japan? It seems that the number of cases in Europe and the US keeps climbing (despite limited/late containment actions), but Japan seems to have it under control, comparatively speaking.
- rbinv 7y ago
  Could be little testing.
  - standardUser 7y ago
    Right, but even without testing, if the progression had followed what we've seen in Iran or Italy, there would be hundreds dying from Covid-19. This is not happening in Japan, and the virus has been in Japan much longer than those countries.
    - tonfa 7y ago
      Also most of Europe does very little testing, but assuming they have uniform criteria, the growth rate should still give some idea of the propagation. For example in Switzerland, they barely test anyone, but it's pretty clear that with +30% d/d growth this is either already everywhere or going to be.
      - standardUser 7y ago
        The virus has been in Japan a lot longer than Italy. Over 2,000 have died in Italy, fewer than 50 in Japan. I have yet to see anything close to a satisfactory explanation.
        literallycancer 7y ago
        First detected case in Italy was January 31st, in Japan it was January 16th and/or 10th (quick Japanese and English Wikipedia check, correct me if you have a better source).
sputr 7y ago
dr. Campbell[1] (the guy on YT explaining the situation every day) said that this seems to be because some people do not clear the virus effectively the first time ... and are picked up again on a later test, but that no proof has been shown that people can get reinfected and will probably be immune for at least a year. [1] https://www.youtube.com/user/Campbellteaching https://www.youtube.com/user/Campbellteaching
- ardit33 7y ago
  He started getting symptoms again, which is the most worrisome part. It is not just simple virus is still lingering around, but it caused an infection again 35+ days after he had it once. I hope this is just a fluke
jeffreyrogers 7y ago
What is the rate of false positives given a positive test result for these tests?
phonebucket 7y ago
While reinfection is ominous and unwelcome, the fact that individual cases like this are newsworthy makes me hopeful that it is a rare phenomenon.
- jshevek 7y ago
  That's what I was thinking. Especially if there is a genetic factor involved, and we can determine that only a small percentage of the population have it, then we could still achieve a level of herd immunity.
dynamite-ready 7y ago
In the current social climate (i.e, false positives perhaps being somewhat less likely, especially in a contrived situation like a cruise ship full of at risk patients) if we assume that the subject truly was infected, cleared, then infected again in such a short time window, what would that mean for all current containment strategies?
- Blahah 7y ago
  It essentially means we need a vaccine to create immunity at scale, and will need to have fairly strict measures in place until that can happen.
  - the_af 7y ago
    I don't understand how a vaccine would work if prior exposure to the virus doesn't prevent re-infection :/ Honest question, no snark intended.
    - mjw1007 7y ago
      Naively, if immunity from prior exposure lasts for a few months, then we might reasonably hope for a vaccine whose effects last for a few months. I suppose if that happened people would get revaccinated frequently.
      - the_af 7y ago
        Ok, but according to the article the man tested positive on Feb 14, then got cleared on March 2 (in Tokyo), returned home and relapsed very few days later. If there are no mistakes in the resting (or reporting), that's not even a few months of immunity...
    - jshevek 7y ago
      Well I think it wouldn't be an 'inactivated' or 'attenuated' vaccine, but we have other vaccine types designed to trick the body into developing the readiness for an immune response. I don't know if they could work for this type of disease. Edit: I glanced at vaccines on Wikipedia, read the following on conjugate vaccines. Maybe we will develop a new technology to do something similar with viruses, training the immune system to recognize the virus by linking it to a toxin? >Conjugate—certain bacteria have polysaccharide outer coats that are poorly immunogenic. By linking these outer coats to proteins (e.g., toxins), the immune system can be led to recognize the polysaccharide as if it were a protein antigen. This approach is used in the Haemophilus influenzae type B vaccine.[41]
Leary 7y ago
I have read many reports of people improving during the middle of the disease when it suddenly takes a bad turn (respiratory failure/cardiac arrest). I wonder if that is at all related to this.
- pvaldes 7y ago
  > I have read many reports of people improving during the middle of the disease when it suddenly takes a bad turn (respiratory failure/cardiac arrest) Medecine is not an exact science. There is a lots of things that can suddenly go wrong in the background. There is the possibility of secondary infection in hospital with opportunistic resistant microbes. And there is also the possibility of foul game, that can't be discarded and would be difficult to prove. Is a low probability but real risk. Unfortunately angels of mercy appear sometimes, often enough to have their own category. https://en.wikipedia.org/wiki/Angel_of_mercy_(criminology) https://en.wikipedia.org/wiki/Angel_of_mercy_(criminology)
pmoriarty 7y ago
Here's what Ralph Baric, an epidemiologist from the University of North Carolina Chapel Hill, had this to say on episode 591 of This Week in Virology[1] a few days ago: Ralph Baric: I saw some very interesting data from Stan Perlman the other day, who has been looking at serum neutralization titers of MERS patients from the Middle East kingdom of Saudi Arabia area and it's quite intersting that people peak fairly quickly with high neutralization titers but then they wane over the next year to almost background levels or just slightly above background levels by the second year, and with MERS there have been several reports of people who have seroconverted. They were RT-PCR positive and their serum neutralizing titers and even ELISA titers went to almost zero within a few months. Baric: And it has not been studied and it should be studied, and this is the contemporary human Coronaviruses -- nobody knows how they maintain themselves in human populations. They don't undergo rapid antigenic variation like influenza. There's not 115 common cold or corona virus type genotypes or whatever they're called, serotypes. Sorry Vincent, I just butchered the coronaviruses. Vincent Racaniello: That's ok. <laughter> Baric: So one hypothesis is that they cause a transient protective immune response that wanes quickly and then they can reinfect and cause mild upper-respiratory tract infections and that's how they maintain themselves. So it is quite possible.. there's been a number now of reported cases in China of SARS2 infections where people were documented to be infected and recovered. They were RT-PCR negative. They went home and they became reinfected a month later or so. Baric: In this case the United States has sufficient cases that we can actually track the serologic responses of the individuals and their general immune.. both B- and T-cell responses after infection and we can get a handle on the long term immunity that may be elicited after infection. On the other hand, from a letter read on an earlier TWiV[2]: 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-591/ http://www.microbe.tv/twiv/twiv-591/ about 15 minutes and 50 seconds in to the program [2] - http://www.microbe.tv/twiv/twiv-588/ http://www.microbe.tv/twiv/twiv-588/ at about 1 hour and 38 minutes in
petilon 7y ago
Is it feasible to create a vaccine against a virus if even infection with a live virus and catching the disease does not give you immunity?
JanSt 7y ago
Reinfection could not occur in SARS-CoV-2 infected rhesus macaques "In this study, our results indicated that the primary SARS-CoV-2 infection could protect from subsequent exposures, which have the reference of prognosis of the disease and vital implications for vaccine design.Importantly, the unsuccessful rechallenge in NHP models suggested that the re-positivity from discharged patients could not be due to reinfection. It needs to consider more complicated issues to find out the causes." https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1.full.pdf https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1.... That's a pretty good sign for an equal response in humans.
- dwaltrip 7y ago
  Looking briefly at the study (I only skimmed the beginning), it seems they attempted the reinfenction quite soon after the recovery from the initial infection. This doesn't tell us anything about how long one may be immune for afterwards. Does anyone have knowledge about the length of periods of immunity (or lack thereof) in various infectious diseases?
  - rimliu 7y ago
    IIRC immunity for coronaviruses typicaly is 6months-two years. And I am not sure , but if you get reinfected after that, once you clear the second infection your immunity will last longer yet.
    - dwaltrip 7y ago
      That sounds pretty good! I hope it's true. I was worried it might be much shorter than that.
    - scotty79 7y ago
      So Boris Johnson will just have to re-infect 50% of UK citizens every 6-24 months while perfectly protecting seniors to keep his idea of herd immunity.
      - 7y ago
wycy 7y ago
The entire theory of the solution to coronavirus hinges on an assumption that it will eventually pass once a critical mass of people have been infected and developed immunity. The handful of stories like this trickling out might imply that the immunity assumption could be incorrect. What would be the ramifications of this? Could corona just bounce around the population for the rest of time, putting everyone at a high percentage chance of dying or requiring hospitalization multiple times a year? Could it be the kind of thing that comes back as a novel form every year like the flu? Could we be seeing covid-20, covid-21, etc ad infinitum, with high mortality/low life expectancy just being a new reality of life? EDIT: If this were the case, and immunity is very shortlived after the virus is gone, maybe it could be contained through giving everyone an extremely frequent regimen of vaccines until this particular strain is out of circulation?
- chickenpotpie 7y ago
  Is it at all possible that we become progressively more immune with each incidence or that we can only be infected N times? If either of these things are true our strategy will still work.
- dooglius 7y ago
  It's not a boolean whether people become immune or not--maybe some small portion of the population have issues developing immunity and the rest are fine?
  - __blockcipher__ 7y ago
    My reasoning is the same, but rather than it being binary, it’s a gradient. So after recovery I might be able to ward off 80% of exposure events that would infect a non-immune person. But given enough exposures or just really bad luck, I could still get infected again. That being said generally in these cases the infection resolves way sooner due to the same mechanism that leads to immunity: immune “memory cells” which wait dormant, ready to start production of immune cels when exposed to the characteristic antigens
- __blockcipher__ 7y ago
ulrikrasmussen 7y ago
A commenter on Reddit claimed that rebound effects are known among patients that have been treated with antiviral medications, and that that could also be a possible explanation: https://www.reddit.com/r/Coronavirus/comments/fjuj24/5075_of_covid19_cases_are_completely_asymptomatic/fkpnet1/ https://www.reddit.com/r/Coronavirus/comments/fjuj24/5075_of...
chiefalchemist 7y ago
Isn't it possible his negative was a false negative? Or even his initial positive was false while having other flu-like symptoms? Then his negative was accurate. And finally he became infected properly.
- raarts 7y ago
  I've also read reports of similar cases that turned out to be just administrative errors. Mixed up identities or just misspellings.
nimish 7y ago
False negatives are a huge issue here. The tests aren't that sensitive. If it was truly recurrent we'd see a lot more than one person since the disease is so contagious.
aaron695 7y ago
I chose to assume it was not a re-infection and it just came back in a rare case, which is very possible. If not, we are dead and it's pointless planing around collapse of society. It makes much more sense to assume we have a solid ( IE at least a year in most cases) herd immunity. Planning around no herd immunity is like planning in depth around bankruptcy at round one funding.

134 points by koolba 7y ago

I was under the impression that one typically becomes immune to diseases like this, but apparently that's not the case? Does anyone have any reliable information here? Is this particular instance what we would typically expect, or can it be explained by test inaccuracy, something unusual about this person, etc.?

kalium_xyz 7y ago
Immunity seems to last only for a short period (few months) but there is not enough evidence to conclude anything yet really. This man might just not have recovered entirely at all though.
deleted 7y ago
[deleted]
gvjddbnvdrbv 7y ago
The Chinese say their are two distinct strains in circulation. Tests are not perfect. Plenty of explanations. Most of them quite uncomfortable.
- jeltz 7y ago
  Do you have a source for that? Because the does not really match my reading of the data on https://nextstrain.org/ncov https://nextstrain.org/ncov.
  - barkerja 7y ago
    https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540747/all/Coronavirus_COVID_19__SARS_CoV_2_ https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX... > Preliminary evidence suggests two strains of SARS-2-CoV circulating: one associated with milder illness (~30%), the other with severe illness (70%).
- pmoriarty 7y ago
  "The Chinese say their are two distinct strains in circulation." This has been debunked on This Week in Virology[1]: Vincent Racaniello: There are a series of articles here, where there have been some claims about different circulating lineages and what that means. Are you on this, Cathy? Cathy Spindler: Right. So, there was an article that I first saw in the LA Times "Chinese Scientists Say Second Coronavirus Strain Is More Dangerous"[2]. But in that there's a link to virological.org, which we talked about another article posted there a couple of weeks ago[3], and they really debunk this and think even that this Chinese article about a second Coronavirus should be retracted. Two of the key claims that are reached by misunderstanding and overinterpreation of data and an additional analysis suffers from methodological limitations. So this long thing on virological.org goes in to the reasons why there's no real evidence for two different strains, a more severe strain and a less severe strain. Rich Condit: It also provides a nice summary of this sort of variation in sequence that's being observed in the virus over time, which is good. Vincent: Yeah, it's a good aritcle. We'll put a link. It's worth reading, but as everyone should know, when these [indistinct] viruses, every replication cycle they sustain mutations in their genomes and the lethal ones are gone, the viruses don't reproduce, but some of them stay and if they're neutral they remain. So they can be characteristic. So the virus introduced in to the Washington area is a single introduction and then it's spread and you can tell that because it has a unique set of mutations compared to say, the Chinese isolate, but it doesn't mean anything biologically. It's just markers. Rich: And the markers are really interesting because they give you insight in to, I mean the insight that I got from observing what came out of the Washington cases is that from looking at the sequence of the virus they concluded that in fact it had been circulating for some time, and they could even get a very very rough estimate of how many cases might be out there based on the variation in sequence and the time at which the disease first showed up in a person. Vincent: I think there are some emails later about this. People are concerned that, and people suggest in these papers, at least the one here, that we're being critical of that it could be evolved to be more virulent or more transmissible. There's no evidence for that whatsoever. Rich: This is the kind of thing that... it just won't go away! Vincent: Oh, it doesn't go away... new outbreak and it comes back. Rich: Yeah, and there's no evidence. People have looked at this. We've gone over this for several.. Zika, Ebola, where's there's been variation and people point to a particular variation and they say, "This is going to make it more virulent" or something, and then the experiments ultimately get done and no. It hasn't made a difference. Vincent: And also the issue of increased transmissibility, I think this virus is already very transmissible as it is, and I think the mutations that made it effectively transmissible among humans, which happened very early on, I don't know, either in animals or in humans early on, before we knew about it, they're done, and it's going to be hard to know what they were. MERS coronavirus has never acquired those high transmissibility changes and it keeps fizzling out and then you have another reintroduction from camels but this particular SARS-Cov-2 sustained them probably early on and it's a very good transmitter. It doesn't need to get better, at least from my anthropocentric view. We never really know what viruses are selected by, but I don't think there's eny evidence, and it's very hard to get that evidence. That paper tells you what you need to prove that mutations are doing something phenotypically. It's very hard to get that. Rich: It has occurred to me that people who don't think about this stuff every day might be a little confused by this discussion relative to the discussion that goes on all the time about variation in influenza virus strains, and new strains coming up and having to change the vaccine and stuff. But that's different. That's variation in the influenza virus that makes it evade the existing immunity, and those sorts of variations arise so you get circulation of viruses that you don't have as good an immune response to, but that's different than a virus making mutations that make it more virulent. It's a different story. [1] - at about 13 minutes in to episode 590 - http://www.microbe.tv/twiv/twiv-590/ http://www.microbe.tv/twiv/twiv-590/ [2] - https://www.latimes.com/science/story/2020-03-05/chinese-scientists-say-second-coronavirus-strain-more-dangerous https://www.latimes.com/science/story/2020-03-05/chinese-sci... [3] - http://virological.org/t/response-to-on-the-origin-and-continuing-evolution-of-sars-cov-2/418 http://virological.org/t/response-to-on-the-origin-and-conti...
alpaca128 7y ago
Apparently in the case of viral infections it is normal to still be tested positive for some time after recovery, up to a few weeks. Unless there is really a confirmation of symptoms reappearing etc. I think this is the most plausible explanation.
Tyr42 7y ago
I know it's possible to have an issue with your immune system not storing the antibodies after fighting off a virus, so you can catch it again. But it's pretty rare?
kzrdude 7y ago
This is just one example, what conclusions can we draw from just that one?
stevenwoo 7y ago
Different corona viruses show different immunity periods after infection. The common cold is one that gives immunity of about a year after infection. We don't know how long immunity will last with covid-19.

geocrasher 7y ago

Edit: Is this lousy testing? Or mutation? It'll be interesting to see how this develops.

gnfisher 7y ago

It is unclear if he was symptomatic in the first positive test. I have read at least some of the tests are capable of giving false positives. Could this have been the case here?

learc83 7y ago
It's more likely that the tests that cleared him were false negatives.
- baxtr 7y ago
  I understand that false negative PCR tests are almost impossible? EDIT: for those down voting. What about this paper then? https://pubmed.ncbi.nlm.nih.gov/32133832/ https://pubmed.ncbi.nlm.nih.gov/32133832/
  - snowmaker 7y ago
    It's the opposite. The PCR tests are more specific (99%) than sensitive (perhaps 90%, we're not really sure).
  - jennyyang 7y ago
    30% chance of false negative which is why they do 2 days in a row, which bring it down to 9% chance of false negatives.
    - PeterisP 7y ago
      Sooo, if you release a thousand patients as cured based on these tests, you'll have 90 false negatives...
  - deleted 7y ago
    [deleted]
  - ohazi 7y ago
    I think you have that backwards. False negative seems extremely plausible. If you're sick, but your viral load is low, it should be possible to collect a sample without a virus particle. If the sample doesn't contain a viral particle, it will necessarily come back negative. False positive seems unlikely, as you'd have to have something that survives several cloning cycles that ends up looking exactly like the markers you're matching against.

standardUser 7y ago

What has caused the slow rate of transmission in Japan? It seems that the number of cases in Europe and the US keeps climbing (despite limited/late containment actions), but Japan seems to have it under control, comparatively speaking.

rbinv 7y ago
Could be little testing.
- standardUser 7y ago
  Right, but even without testing, if the progression had followed what we've seen in Iran or Italy, there would be hundreds dying from Covid-19. This is not happening in Japan, and the virus has been in Japan much longer than those countries.
  - tonfa 7y ago
    Also most of Europe does very little testing, but assuming they have uniform criteria, the growth rate should still give some idea of the propagation. For example in Switzerland, they barely test anyone, but it's pretty clear that with +30% d/d growth this is either already everywhere or going to be.
    - standardUser 7y ago
      The virus has been in Japan a lot longer than Italy. Over 2,000 have died in Italy, fewer than 50 in Japan. I have yet to see anything close to a satisfactory explanation.
      - literallycancer 7y ago
        First detected case in Italy was January 31st, in Japan it was January 16th and/or 10th (quick Japanese and English Wikipedia check, correct me if you have a better source).

sputr 7y ago

dr. Campbell[1] (the guy on YT explaining the situation every day) said that this seems to be because some people do not clear the virus effectively the first time ... and are picked up again on a later test, but that no proof has been shown that people can get reinfected and will probably be immune for at least a year. [1] https://www.youtube.com/user/Campbellteaching https://www.youtube.com/user/Campbellteaching

ardit33 7y ago
He started getting symptoms again, which is the most worrisome part. It is not just simple virus is still lingering around, but it caused an infection again 35+ days after he had it once. I hope this is just a fluke

jeffreyrogers 7y ago

What is the rate of false positives given a positive test result for these tests?

phonebucket 7y ago

While reinfection is ominous and unwelcome, the fact that individual cases like this are newsworthy makes me hopeful that it is a rare phenomenon.

jshevek 7y ago
That's what I was thinking. Especially if there is a genetic factor involved, and we can determine that only a small percentage of the population have it, then we could still achieve a level of herd immunity.

dynamite-ready 7y ago

In the current social climate (i.e, false positives perhaps being somewhat less likely, especially in a contrived situation like a cruise ship full of at risk patients) if we assume that the subject truly was infected, cleared, then infected again in such a short time window, what would that mean for all current containment strategies?

Blahah 7y ago
It essentially means we need a vaccine to create immunity at scale, and will need to have fairly strict measures in place until that can happen.
- the_af 7y ago
  I don't understand how a vaccine would work if prior exposure to the virus doesn't prevent re-infection :/ Honest question, no snark intended.
  - mjw1007 7y ago
    Naively, if immunity from prior exposure lasts for a few months, then we might reasonably hope for a vaccine whose effects last for a few months. I suppose if that happened people would get revaccinated frequently.
    - the_af 7y ago
      Ok, but according to the article the man tested positive on Feb 14, then got cleared on March 2 (in Tokyo), returned home and relapsed very few days later. If there are no mistakes in the resting (or reporting), that's not even a few months of immunity...
  - jshevek 7y ago
    Well I think it wouldn't be an 'inactivated' or 'attenuated' vaccine, but we have other vaccine types designed to trick the body into developing the readiness for an immune response. I don't know if they could work for this type of disease. Edit: I glanced at vaccines on Wikipedia, read the following on conjugate vaccines. Maybe we will develop a new technology to do something similar with viruses, training the immune system to recognize the virus by linking it to a toxin? >Conjugate—certain bacteria have polysaccharide outer coats that are poorly immunogenic. By linking these outer coats to proteins (e.g., toxins), the immune system can be led to recognize the polysaccharide as if it were a protein antigen. This approach is used in the Haemophilus influenzae type B vaccine.[41]

Leary 7y ago

I have read many reports of people improving during the middle of the disease when it suddenly takes a bad turn (respiratory failure/cardiac arrest). I wonder if that is at all related to this.

pvaldes 7y ago
> I have read many reports of people improving during the middle of the disease when it suddenly takes a bad turn (respiratory failure/cardiac arrest) Medecine is not an exact science. There is a lots of things that can suddenly go wrong in the background. There is the possibility of secondary infection in hospital with opportunistic resistant microbes. And there is also the possibility of foul game, that can't be discarded and would be difficult to prove. Is a low probability but real risk. Unfortunately angels of mercy appear sometimes, often enough to have their own category. https://en.wikipedia.org/wiki/Angel_of_mercy_(criminology) https://en.wikipedia.org/wiki/Angel_of_mercy_(criminology)

pmoriarty 7y ago

Here's what Ralph Baric, an epidemiologist from the University of North Carolina Chapel Hill, had this to say on episode 591 of This Week in Virology[1] a few days ago: Ralph Baric: I saw some very interesting data from Stan Perlman the other day, who has been looking at serum neutralization titers of MERS patients from the Middle East kingdom of Saudi Arabia area and it's quite intersting that people peak fairly quickly with high neutralization titers but then they wane over the next year to almost background levels or just slightly above background levels by the second year, and with MERS there have been several reports of people who have seroconverted. They were RT-PCR positive and their serum neutralizing titers and even ELISA titers went to almost zero within a few months. Baric: And it has not been studied and it should be studied, and this is the contemporary human Coronaviruses -- nobody knows how they maintain themselves in human populations. They don't undergo rapid antigenic variation like influenza. There's not 115 common cold or corona virus type genotypes or whatever they're called, serotypes. Sorry Vincent, I just butchered the coronaviruses. Vincent Racaniello: That's ok. <laughter> Baric: So one hypothesis is that they cause a transient protective immune response that wanes quickly and then they can reinfect and cause mild upper-respiratory tract infections and that's how they maintain themselves. So it is quite possible.. there's been a number now of reported cases in China of SARS2 infections where people were documented to be infected and recovered. They were RT-PCR negative. They went home and they became reinfected a month later or so. Baric: In this case the United States has sufficient cases that we can actually track the serologic responses of the individuals and their general immune.. both B- and T-cell responses after infection and we can get a handle on the long term immunity that may be elicited after infection. On the other hand, from a letter read on an earlier TWiV[2]: 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-591/ http://www.microbe.tv/twiv/twiv-591/ about 15 minutes and 50 seconds in to the program [2] - http://www.microbe.tv/twiv/twiv-588/ http://www.microbe.tv/twiv/twiv-588/ at about 1 hour and 38 minutes in

petilon 7y ago

Is it feasible to create a vaccine against a virus if even infection with a live virus and catching the disease does not give you immunity?

JanSt 7y ago

Reinfection could not occur in SARS-CoV-2 infected rhesus macaques "In this study, our results indicated that the primary SARS-CoV-2 infection could protect from subsequent exposures, which have the reference of prognosis of the disease and vital implications for vaccine design.Importantly, the unsuccessful rechallenge in NHP models suggested that the re-positivity from discharged patients could not be due to reinfection. It needs to consider more complicated issues to find out the causes." https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1.full.pdf https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1.... That's a pretty good sign for an equal response in humans.

dwaltrip 7y ago
Looking briefly at the study (I only skimmed the beginning), it seems they attempted the reinfenction quite soon after the recovery from the initial infection. This doesn't tell us anything about how long one may be immune for afterwards. Does anyone have knowledge about the length of periods of immunity (or lack thereof) in various infectious diseases?
- rimliu 7y ago
  IIRC immunity for coronaviruses typicaly is 6months-two years. And I am not sure , but if you get reinfected after that, once you clear the second infection your immunity will last longer yet.
  - dwaltrip 7y ago
    That sounds pretty good! I hope it's true. I was worried it might be much shorter than that.
  - scotty79 7y ago
    So Boris Johnson will just have to re-infect 50% of UK citizens every 6-24 months while perfectly protecting seniors to keep his idea of herd immunity.
    - 7y ago

wycy 7y ago

The entire theory of the solution to coronavirus hinges on an assumption that it will eventually pass once a critical mass of people have been infected and developed immunity. The handful of stories like this trickling out might imply that the immunity assumption could be incorrect. What would be the ramifications of this? Could corona just bounce around the population for the rest of time, putting everyone at a high percentage chance of dying or requiring hospitalization multiple times a year? Could it be the kind of thing that comes back as a novel form every year like the flu? Could we be seeing covid-20, covid-21, etc ad infinitum, with high mortality/low life expectancy just being a new reality of life? EDIT: If this were the case, and immunity is very shortlived after the virus is gone, maybe it could be contained through giving everyone an extremely frequent regimen of vaccines until this particular strain is out of circulation?

chickenpotpie 7y ago
Is it at all possible that we become progressively more immune with each incidence or that we can only be infected N times? If either of these things are true our strategy will still work.
dooglius 7y ago
It's not a boolean whether people become immune or not--maybe some small portion of the population have issues developing immunity and the rest are fine?
- __blockcipher__ 7y ago
  My reasoning is the same, but rather than it being binary, it’s a gradient. So after recovery I might be able to ward off 80% of exposure events that would infect a non-immune person. But given enough exposures or just really bad luck, I could still get infected again. That being said generally in these cases the infection resolves way sooner due to the same mechanism that leads to immunity: immune “memory cells” which wait dormant, ready to start production of immune cels when exposed to the characteristic antigens
__blockcipher__ 7y ago

ulrikrasmussen 7y ago

A commenter on Reddit claimed that rebound effects are known among patients that have been treated with antiviral medications, and that that could also be a possible explanation: https://www.reddit.com/r/Coronavirus/comments/fjuj24/5075_of_covid19_cases_are_completely_asymptomatic/fkpnet1/ https://www.reddit.com/r/Coronavirus/comments/fjuj24/5075_of...

chiefalchemist 7y ago

Isn't it possible his negative was a false negative? Or even his initial positive was false while having other flu-like symptoms? Then his negative was accurate. And finally he became infected properly.

raarts 7y ago
I've also read reports of similar cases that turned out to be just administrative errors. Mixed up identities or just misspellings.

nimish 7y ago

False negatives are a huge issue here. The tests aren't that sensitive. If it was truly recurrent we'd see a lot more than one person since the disease is so contagious.

aaron695 7y ago

I chose to assume it was not a re-infection and it just came back in a rare case, which is very possible. If not, we are dead and it's pointless planing around collapse of society. It makes much more sense to assume we have a solid ( IE at least a year in most cases) herd immunity. Planning around no herd immunity is like planning in depth around bankruptcy at round one funding.