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China Medicine

A Third of Coronavirus Cases May Be 'Silent Carriers', Classified Chinese Data Suggests (scmp.com) 112

The number of "silent carriers" -- people who are infected by the new coronavirus but show delayed or no symptoms -- could be as high as one-third of those who test positive, according to classified Chinese government data seen by the South China Morning Post. An anonymous reader writes: That could further complicate the strategies being used by countries to contain the virus, which has infected more than 300,000 people and killed more than 14,000 globally. More than 43,000 people in China had tested positive for Covid-19 by the end of February but had no immediate symptoms, a condition typically known as asymptomatic, according to the data. They were placed in quarantine and monitored but were not included in the official tally of confirmed cases, which stood at about 80,000 at the time. Scientists have been unable to agree on what role asymptomatic transmission plays in spreading the disease. A patient usually develops symptoms in five days, though the incubation period can be as long as three weeks in some rare cases.
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A Third of Coronavirus Cases May Be 'Silent Carriers', Classified Chinese Data Suggests

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  • Assume you have it (Score:5, Informative)

    by OffTheLip ( 636691 ) on Monday March 23, 2020 @10:10AM (#59862704)
    or will get it. Isolation is the best we can do at this time.
    • Re: (Score:1, Informative)

      by Anonymous Coward
      Sorry, bud. New Englander here, and I work for one of the major airlines in the flight ops center. Somebody brought it into the office, and a bunch of us got it around January. I had a cough after I ate, muscle and joint aches, and felt malaise for a few days. Went on for three weeks. I never had to sneeze. I recovered a month ago. Was livid that there were no tests. I'll get an antibody test in six months if such a thing is offered so that I can fully confirm.

      TLDR: it's been in CONUS for months now, and i
      • by Way Smarter Than You ( 6157664 ) on Monday March 23, 2020 @10:46AM (#59862836)
        How do you know it was cv and not standard flu? January is the height of flu season. Assuming the other person tested positive for cv still doesn't mean that's what you had.

        My kid had cv-like symptoms a month ago. No tests. Got over it in a few days. I had something later that week. What did we have? Who knows? Could be anything.
        • by kbahey ( 102895 )

          How do you know it was cv and not standard flu? January is the height of flu season. Assuming the other person tested positive for cv still doesn't mean that's what you had.

          My kid had cv-like symptoms a month ago. No tests. Got over it in a few days. I had something later that week. What did we have? Who knows? Could be anything.

          We don't know now, but as time progresses, there will be a blood serum test that tell if you have the antibodies for it, just like there is one for tuberculosis, Hepatitis, ...etc.

          I

        • If one looks at the cruise ship and jail data (Closed, trapped communities, where 100% were tested) then it suggests that about 80% of them have immunity to the disease. So the vast majority of people on the planet already encountered the virus (or a close cousin of it) before.
          • If one looks at the cruise ship and jail data (Closed, trapped communities, where 100% were tested) then it suggests that about 80% of them have immunity to the disease. .

            Errrr... 'scuse me link please. . Or actually "bullshit" ; on some of the cruise liners most of the people caught the disease, so unless you are claiming that this was a mistaken diagnosis then this must be wrong.

            • The Diamond Princess cruise ship was marooned off the coast of Japan for weeks and newspaper reporters were going crazy about how this was a Petri Dish, the Quarantine Failed, Everybody would be infected and 6 to 8% would Die.

              Fortunately, reality was different:
              Number of passengers: 3700
              Number of passengers tested for Corona virus: 3700
              Number infected: 621
              Number of deaths: 2 (both >80y)

              No matter which numbers you divide by which, 6% it ain't. More like 0.05% mortality - two orders of magnitude le

              • by tbird20d ( 600059 ) on Monday March 23, 2020 @02:27PM (#59863642)
                Your numbers are off. The sample size is very small, and admittedly this was a population at increased risk (elderly passengers), but the number of infections was/is over 700, and the number of deaths as of March 22 is now 11. See https://en.wikipedia.org/wiki/... [wikipedia.org] where it is documented down to the individuals. SARS-CoV-2 infects fast, but in some cases kills slowly, so it's too early to determine the mortality rate.
          • I am pretty sure you are making a poor assumption; the cruise ship did not have full contact between people for the duration of quarantine; hence the term quarantine. If you take R0 as 5, that gives you four generations of infections to reach about 700. If they continued to operate as normal, it is likely that a much larger percentage of people would have contracted the virus, although not 100% based on how people circulate.

            There is a good percentage of people that are likely to be “walking wounded,

        • How do you know it was cv and not standard flu?

          Of course he doesn't know. This is pretty much the same thing as someone having a badly infected wound and figuring "Oh it must be MRSA" without actually testing it because they think MRSA means "bad infection" and not "Infection that's resistant to current drugs but your immune system might fight it off just the same."

      • by jellomizer ( 103300 ) on Monday March 23, 2020 @01:04PM (#59863386)

        The problem isn't necessarily the workers, I expect you are healthy in your 20's-50's where it is just like a bad cold of flu where you can just sleep it off after a few weeks. It sucks but isn't a big deal. However other people in your office, or your family. May not be as tolerant as you, and unlike the Flu has a higher percentage of fatal complications for already vulnerable people.

        The isolation isn't as much about saving lives, but lowering the rate of people catching it, so the healthcare infrastructure can deal with it. Because Hospitals besides dealing with Covid also have to deal with people who get sick and injured from different stuff too.

        • Unfortunately that can be nearly impossible. Without a positive test (which you can’t get), how do you know when you can stop full isolation? Does it just go on forever? Does the clock keep resetting any time you come into contact with a new person?

          • by Anonymous Coward

            Unfortunately that can be nearly impossible. Without a positive test (which you can’t get), how do you know when you can stop full isolation? Does it just go on forever? Does the clock keep resetting any time you come into contact with a new person?

            It doesn't really matter.. Evidence says that the virus can be shed for 7-10 days after symptoms are gone. Same story with other viruses like this one. Stay home a week. Your bro's will be fine.

            Look, we are pretty much ALL going to get this one eventually. Most of us won't have any symptoms at all, some will have serious complications. The Current "social distancing," work from home, and shelter in place orders are really only an effort to manage medical resources. We only have so many hospital beds a

          • The neat thing with Math and Science is that they are models and simulations you can run. I wish I remembered to save the link, but it was a page with 3 simulations.
            One with just random movement. The next one with a quarantine. The last model with most people staying in place with minimal movements.
            The models show limiting your movements is better because it reduces the total number of people ill at any one moment.

      • by Ost99 ( 101831 )

        The symptoms and the timing suggests the seasonal flu, not cv.

      • isolation is just going to kill the economy

        Perhaps not, with a $4T recovery package. This is an election year, Republicans are stuck in power so they can't preach austerity.

      • Flight Ops center is a risky place to be now. I have a friend in CT who has symptoms and been sent to get tested by his Dr to the nearest testing center (30 miles away) where he was turned away due to not being on the list. He also works in aviation.
    • ofcourse, and stay isolated until we know who's a silent carrier ... uncle Po is gonna love that :) ...
      i still feel ... (i do sometimes ... feel , like , on occasion it comes back to me) sars 1 : 800 victims in 8 months , sars2 : 14.000 in 3 months ...
      everyone on slashdot can count to three ... this is just an exercise in logistics for when Twelve Monkeys attacks (or call it the wrath of god by number 4 as civilization has collapsed and we're drinking out of skulls ...)
  • by Errol backfiring ( 1280012 ) on Monday March 23, 2020 @10:13AM (#59862716) Journal

    That could further complicate the strategies being used by countries to contain the virus

    I don't think that complicates the strategies. It is already known that the virus is contagious even when no symptoms are present. So the present strategies (at least where I live) are aimed at slowing down possibly contagious contacts between people to slow down the rush in the need of medical assistance. That there are also people who do not get sick at all is just a bonus for the medical crews. They will probably develop antibodies and stop spreading the virus after a while.

    • by burtosis ( 1124179 ) on Monday March 23, 2020 @10:20AM (#59862754)
      It’s unknown how long those antibodies will remain effective for this strain (or closely related ones). Other Coronavirus infections have shown it’s possible to be re-infected long term. It’s probably not less than six months, but if it’s less than two years we may be in for real serious trouble. Here’s to hoping it’s decades.
      • by Anonymous Coward

        It’s unknown how long those antibodies will remain effective for this strain (or closely related ones). Other Coronavirus infections have shown it’s possible to be re-infected long term. It’s probably not less than six months, but if it’s less than two years we may be in for real serious trouble. Here’s to hoping it’s decades.

        A booster vaccine will likely be ready in just less than a year. They will just keep it as part of the yearly Flu shot and that will help keep things under control.

        • Re: (Score:2, Informative)

          by Anonymous Coward

          A booster vaccine will likely be ready in just less than a year.

          Don't count on it. They never made a vaccine for the common cold (which is a coronavirus), and they failed miserably at attempts for a vaccine against SARS (the forerunner of COVID-19). Instead of curing test subjects, the SARS vaccine caused a cytokine storm, killing the subject.

          • How did that get modded informative when they don't even know what cold [wikipedia.org] is?

            The common cold is a viral infection of the upper respiratory tract. The most commonly implicated virus is a rhinovirus (30–80%), a type of picornavirus with 99 known serotypes.[29][30] Other commonly implicated viruses include human coronavirus ( 15%),[31][32] influenza viruses (10–15%),[33] adenoviruses (5%),[33] human respiratory syncytial virus (orthopneumovirus), enteroviruses other than rhinoviruses, human parainfluenza viruses, and human metapneumovirus.[34] Frequently more than one virus is present.[35] In total, more than 200 viral types are associated with colds.[3]

            That's why there isn't a cure for 'common cold'. Because it's not just 1 thing.

            We have vaccines for Influenza, and that mutates twice as fast as coronavirus do.

            SARS and MERS we ran out of infected people to test with and lost interest. Don't think that will be a problem this time.

      • The problem isn't just the production of antibodies stopping, it's that the virus mutates. There are hundreds of variants of the coronavirus. This is just a single variant and after it infects a few billion people it will evolve and be back next year.

    • I don't think that complicates the strategies. It is already known that the virus is contagious even when no symptoms are present.

      In dealing with a pandemic, we rely on a lot of statistical information to try to predict how much equipment is going to be needed, where, and when. Then you've got all the people that are going to ignore recommendations of self-isolation because not many cases have been reported in their area. Those two factors will probably exacerbate the situation.

  • by ebonum ( 830686 ) on Monday March 23, 2020 @10:15AM (#59862734)

    How many of these Covid-19 positives are due to another variation of the Corona virus or are false positives due to poor quality control of the test kits?

  • What words mean (Score:3, Insightful)

    by burtosis ( 1124179 ) on Monday March 23, 2020 @10:17AM (#59862740)
    Asymptomatic: does not exhibit symptoms at all

    Presymptomatic: Has not yet exhibited symptoms.

    If every media source would stop confusing the two terms it would clear up so, so many, misunderstandings.
    • What exactly would it clear up, especially specifically regarding COVID-19 ? As my understanding is it can both be completely asymptomatic , as well as presymptomatic in other cases.

      It's been reported generally x% of cases are asymptomatic. x% are presymptomatic. x% are suffering. x% are dead.

      Give some examples - because I feel like people have a good handle on this.

      Or are you just virtue signalling you know what words mean ?

    • by Anonymous Coward

      Asymptomatic: does not exhibit symptoms at all

      This label includes both those who have not yet started to exhibit symptoms but may (or may not) do so at a later point in time, as well as those who never did despite having been carriers.

      Presymptomatic: Has not yet exhibited symptoms.

      Only possible to assign after starting to exhibit symptoms, and then only to a span of time already in the past.

      If every media source would stop confusing the two terms it would clear up so, so many, misunderstandings.

      What misunderstandings would that be and what would this solve, if anything?

      A person can at any point in time be one of:
      - 1. Uninfected, and thus asymptomatic.
      - 2. Infected, but so far asymptomatic.
      - 3. Symptoma

    • Asymptomatic raises the question of how much less infectious they might be. Not coughing and sneezing is going to interfere with spraying aerosols of virus to spread the infection.

    • News Flash:

      News Media gets Scientific Terms wrong. News at 11.

      In all seriousness the media has always gotten science terms, definitions and descriptions wrong since pretty much the beginning. This is what happens with journalism majors report on science because the vast majority of them never took any science in college, and lets be honest the vast majority of them aren't smart enough to get it right without assistance from actual scientists.

      • Some sources actually have pretty good science reporting, the Grauniad springs immediately to mind. Another problem with scientists talking to the media is that if it's not done via the trained media spokesperson for the science org then there's a severe impedance mismatch between the person providing the information and the person recording it. Another problem I've run into is that a common scientific practice of asking to check what'll be written to make sure there's no misinterpretation is strongly res
  • Yeah, like, just about everybody between the ages of 5 - 18 years old. Largely asymptomatic super spreaders, according to the data from the modeling report dated March 16 showing UK and USA potential spread. https://www.imperial.ac.uk/med... [imperial.ac.uk]
    • This is an argument that schools should have all been shut down a month ago. However, that also shuts down large parts of the economy, so no one would go for it.

      • This is an argument that schools should have all been shut down a month ago. However, that also shuts down large parts of the economy, so no one would go for it.

        BuckNikked

        Chinese schools simply never reconvened when its extensive New Year holiday ended. Any position that asserts what ~1.3 billion people undertook to prioritize saving lives over ANY economic analysis as insufficient warning upends any use of the word civilized. The phrase "an abundance of caution" migrated from public health to markets of trade and no argument of exception is meaningful armor or haven from the natural sciences that are implacable in character.

  • by Dixie_Flatline ( 5077 ) <vincent.jan.gohNO@SPAMgmail.com> on Monday March 23, 2020 @10:30AM (#59862786) Homepage

    Test everyone. Test often. From my understanding, there are simple blood tests that can detect antibodies very quickly—something like 15 minutes; it's what they're using in South Korea—and that should be the broadest base of testing. It relies on an immune response, yes, but it's better than nothing. It's fast and easy and it will let us take the vast majority of infected carriers out of the population.

    Test, test, test and then test some more. That's the only way out of this mess. We can't keep cities locked down forever, and while we all know to 'flatten the curve', there comes a time where we need to just stop the spread, period. You can't do that if you're flying blind with the number of infections and who the carriers are. One infectious disease expert I read said that you can still be contagious 3-4 weeks after recovering. Between that and asymptomatic carriers, we just won't be able to claw our way out of this without having good data.

    • Comment removed based on user account deletion
    • by AnonCowardSince1997 ( 6258904 ) on Monday March 23, 2020 @11:07AM (#59862922)

      From my understanding, there are simple blood tests that can detect antibodies very quickly—something like 15 minutes; it's what they're using in South Korea—and that should be the broadest base of testing.

      No they are not. South Korea is using PCR tests.

      “These are PCR (polymerase chain reaction) tests - in very basic terms it is searching for the presence of Covid-19 in the sample. The whole process from test tube to test result is about five to six hours.” — From: Coronavirus in South Korea: How 'trace, test and treat' may be saving lives [bbc.co.uk].

      PCR-based test are the current best way to test for an active infection. Antibody tests are best for looking for a past infection - not suitable if you want to be able to advise a patient to go into isolation or if they may need treatment. Antibody tests may be useful in the future to find those that have had the virus and recovered with some immunity, or have had asymptotic infections. Though there are some studies saying it may be possible to have this coronavirus more than once, which would be very bad.

      • Ah, I must have misremembered or have them confused with another jurisdiction. Thanks for the correction!

        My understanding on having it more than once is that for now, most or all of the studied cases were probably relapses, but there's a very real possibility that this will be like the cold, where you can get it every year because it'll change just enough, or our immunity will be fairly time-limited, unlike with diseases like chicken pox or measles.

        • by Anonymous Coward

          My understanding on having it more than once is that for now, most or all of the studied cases were probably relapses, but there's a very real possibility that this will be like the cold, where you can get it every year because it'll change just enough, or our immunity will be fairly time-limited, unlike with diseases like chicken pox or measles.

          No, it's probably more like herpes, which goes dormant, then pops back up whenever you're stressed out or whenever it feels like fucking you over again.

          Chicken pox works like that too. When you get chicken pox as a child, your body fights it off, but really its just gone dormant. It comes back when you get older because your immune system starts declining. They call it shingles when you're older, but it's really the same virus that caused chicken pox when you were young.

    • Even simpler strategy: Do nothing.
      (The Taiwan strategy)

      It is still not clear that intervention makes any difference at all to the outcome of this disease. Some people THINK it does, but the fact is that we have very little reliable information on how this virus spreads in the community.

      We are trying to protect the old and weak, at great cost, but it really isn't clear whether it helps at all.

      • Even simpler strategy: Do nothing.
        (The Taiwan strategy)

        That's the Dutch/British strategy. The Taiwanese are very proactively working to contain Roni:

        [Measures] included screening incoming travellers for fever and implementing a system of rationing face masks to prevent hoarding.

        The steps also included mandatory self-quarantine for people who had recently travelled to affected parts of the world, while self-isolation was recommended for those who had come in contact with potentially exposed individuals. The existing neighbourhood warden system facilitated enforcement of the quarantines and helped deliver meals and other assistance to those who needed it.
        [...]
        All travellers returning from abroad are now required to undergo two weeks of self-quarantine.

        https://www.channelnewsasia.co... [channelnewsasia.com]

      • This is exactly the right answer. The best we CAN do is keep things rolling so people can afford to get treated, will not delay because their hours are cut back. This is the first real "Social Media" pandemic we've had, and - while all numbers show it's no more deadly than H1N1, SARS, or others - it's blown WAY out of proportion because of the preponderance of social media used to let everyone express their fears - and feed on those of others.
        • Yeah, tell that to the Italians.

          • And what has all the actions they've taken done to solve the problem? What has completely shuttering their economy done? It's definitely not solved any coronavirus issue - and has put hundreds of thousands at MORE risk for health issues (that they cannot afford as the economy has stopped).
        • by dgatwood ( 11270 ) on Monday March 23, 2020 @02:49PM (#59863686) Homepage Journal

          while all numbers show it's no more deadly than H1N1, SARS, or others

          In what sense? SARS killed a total of 774 people worldwide. So far, COVID-19 has killed over 16,000 people worldwide.

          We're on track for it to match the 2009 death rate from H1N1 by the end of this week, and folks didn't shelter in place en masse to try to stop H1N1 from spreading.

          Now if you mean the Spanish flu variant of H1N1 (back in 1918), then yes, this is probably comparable. If we handle it the way they handled that back in 1918, after adjusting for the increased world population, we would expect 200 million fatalities. But COVID-19 seems to spread more easily than influenza, so 400 million is probably a more realistic estimate.

          This is NOT being blown way out of proportion. A highly virulent disease with even a 1% infection fatality rate (IFR) is utterly insane. Calling COVID-19 the plague of the century is not an overstatement.

        • while all numbers show it's no more deadly than H1N1, SARS, or others
          The numbers show clearly that it is more deadly.
          SARS: 774 dead
          MERS: 282
          H1N1: about 1 million over two years

          COVID-19: 16,000 over 3 - 4 month.

          • Hmmm... You list H1N1 as killing 1,000,000 over 24 months - about 41,000 per month. We're seeing 4,000 per month right now. That's an order of magnitude less than H1N1.

            SARS, while a lower number of deaths, was a solid 15% fatality rate [healthline.com] - more than an order of magnitude higher than this virus.

            MERS has a 34% mortality rate [who.int], again more than an order of magnitude more deadly than this Wuhan virus.

            I'll stand by my claim - and that this is really not such a big deal, such that we have to destroy the economy

            • Hmmm... You list H1N1 as killing 1,000,000 over 24 months - about 41,000 per month. We're seeing 4,000 per month right now. That's an order of magnitude less than H1N1.
              Because corvid is at the moment locally contained and the total number of infected is 350k and not 3 billions. The number is not an order of magnitude less it is 3 orders of magnitudes more, likely more than 4 orders of magnitude.


              SARS, while a lower number of deaths, was a solid 15% fatality rate - more than an order of magnitude higher than

              • I'll give you a pass since English isn't your first language. "More Deadly" refers to how many people who catch it will die. Over 3 million people are bitten by snakes each year, the vast majority aren't lethal; yet those bit by the Inland Taipan die at a ~80% rate. It's deadly, compared to the other snakes. Just like MERS and SARS and H1N1 are much more deadly than the Wuhan virus.
              • by bongey ( 974911 )

                Actually on slashdot everyone is an epidemic expert.

            • Hmmm... You list H1N1 as killing 1,000,000 over 24 months - about 41,000 per month. We're seeing 4,000 per month right now. That's an order of magnitude less than H1N1.

              You're a bit out of date.
              Yesterday was over 1,000 for just Italy and Spain [worldometers.info]
              Today's numbers haven't even finished counting and it's already higher.
              Just 2 countries is already at 30,000 a month equivalent and getting worse. Add in the other countries...
              Certainly not an order of magnitude less, but actually higher.

              Just more Republican, just a cold downplaying.
              The last 5 days have all had over 1,000 deaths each. Every day higher than the previous.

              I'll stand by my claim - and that this is really not such a big deal

              Of course you will. Your ship is unsinkable, it's only an i

            • We're seeing 4,000 per month right now.

              LOL @ the denialist himself... Daily death toll [worldometers.info]
              21 March 1,626
              22 March 1,628
              23 March 1,873
              = 5,172
              Do months only have 3 days in your country?
              We will have 4,000 cases in a weekend soon. And then 4,000 a day if we don't get on top of this.

            • I'll stand by my claim - and that this is really not such a big deal,

              We just had 4 days in a row with over 2,000 deaths...
              March 24-27
              Wonder if tomorrow will be 4,000...

      • Taiwan is testing a lot. They're not doing nothing at all. Where did you get that idea? They test anyone with symptoms and quarantine them, and reduce spread dramatically.

      • Taiwan was the first reacting nation ... calling that "doing nothing" is a strange attitude.

    • That's what needs to be done. New York reported that there are 20,000 cases, but those are only confirmed cases. If 30% of infected people are asymptomatic as some estimates suggest, then this number could be much higher. Then, there are the mild cases where people stay home with "the flu" (either mistaking it for the flu due to similar symptoms or just not getting tested due to lack of tests and mild symptoms) for a few days and don't add into the total. So there could easily be double or triple the cases

  • I've heard concerns that the tests themselves aren't standardized across countries and count potentially test positive for other coronaviruses, not just SARS-Cov2 (25% of colds are caused by other coronaviruses). Could these people simple have other coronaviruses and not SARS-Cov2?

    • by Orgasmatron ( 8103 ) on Monday March 23, 2020 @12:26PM (#59863236)

      Responding here about the testing even though there are plenty of other comments asking similar questions.

      There is a standard PCR plate with 8 rows of 12 wells. You need two wells in each row for controls (one with enzymes but no sample - should not light up, but will if contaminated; and one with enzymes and a sample that proves that the PCR machine is working). There are, I think four standard dyes, so in theory you could test 4 xNA sequences per well.

      I read the CDC protocol a few days ago, and I didn't think they were using multiple dyes per well. In other words, and assuming that I'm remembering that right, they felt that they had found 10 sequences that, taken together, were specific to this virus, and common to all strains of this virus.

      A realtime PCR test (ignoring the RNA and reverse transcriptase parts) uses primers and probes, all of which are customized for what you are testing. This customization is what takes time between reading the target genome and publishing the first test.

      PCR happens between two primers. The primers are sequences of amino acides, just like DNA, so they bind to a matching spot. One of them is the start marker, and the other is the end marker. The PCR cycle duplicates everything between them.

      The other part is the probe. The probe has a sequence of amino acids, so it also binds to a specific sequence. But unlike the primers which are tagged to aim the PCR process at the right spot, the probes are tagged with flourescent dyes.

      So, each site is a test for the presence of a specific sequence, found between two other specific sequences. If the end sequences aren't present, the chain won't copy. If the center sequence isn't present, the chain will copy, but the probe won't bind to it. If you have all three in the same solution, they will copy AND the dye will activate. After each cycle of the PCR, you activate the dye and measure the flouresence that it causes. If you have a match, there will be a bright spot that get brighter and brighter with each cycle. The "real-time" part of RRT-PCR involves tracking the brightness as it grows with each cycle.

      (I'm simplifying a lot - in reality the probe is both flourescent and quenching. Binding to the target site spreads them apart, which reduces the effectiveness of the quencher.)

      Modern PCR machines using modern enzymes take a couple of minutes per cycle. You need around 40 cycles for the test. High throughput machines can pause between cycles to add plates. Imagine a CPU where every instruction takes 40 clock cycles, but it has an instruction pipeline, so once it is running, there is an instruction finishing with each cycle. Bigger labs will have multicore CPUs, and the huge labs will have beowulf clusters of multicore pipelined PCR machines - this is how you get tens of thousands of tests done per day.

      So, there were 11 days between the publication of the virus genome and the publication of the first test. What happened in that time? The researchers were scanning the genome, and other genome databases, looking for candidate sites. They needed to identify sequences that 1) were present in the virus, 2) were primer-able, 3) were probe-able, 4) were specific to the virus, and 5) that didn't mutate often enough to moot the test.

      Part of the US regulatory scheme prior to this is that the CDC labs certify that their test is correct (accurate and specific), and the FDA verifies it and approves it for diagnostic use. Then they find a contractor to produce the enzymes and ship them out to distant labs. There was a problem with the first stuff sent out, which sometimes happens because this stuff is hard. But, because of the regulatory monoculture, that meant that no one had a working test. President Trump approved a regulatory change which allowed other labs to produce their own tests and get them verified and certified, rather than waiting for the CDC test to get straightened out.

      So, to more directly address the concerns that you report, it is correct that there isn't one definitive test. But the people who do this sort of stuff are well aware of the other related viruses and they put a lot of effort into excluding them from tests like this.

    • I've heard concerns that the tests themselves aren't standardized across countries and count potentially test positive for other coronaviruses, not just SARS-Cov2 (25% of colds are caused by other coronaviruses). Could these people simple have other coronaviruses and not SARS-Cov2?

      Not likely. The tests are designed to look for gene targets unique to the SARS-Cov-2 viruses (there are now multiple strains). 100s of coronaviruses have been sequenced, so researchers can know what to choose for a target. There are very good tools for studying RNA/DNA sequences and creating a phylogeny based on common sequences. To choose a target you chose a sequence unique to the SARS-CoV-2 family. A few unique sequences have been found and the target each country’s “CDC” selected have

  • by kbahey ( 102895 ) on Monday March 23, 2020 @11:15AM (#59862948) Homepage

    There are still lots of unknowns about this virus.

    Things like how long does it stay on surfaces? Different studies quote different times. Some of these studies are on related Coronavirus species. At least one is on the SARS-CoV-2. What I do is leave stuff that is delivered to the house for two days before unpacking it. But is that enough? Who knows ...

    There is also evidence of fecal shedding while throat swab test negative [thelancet.com]. One patient showed shedding for 33 days, another for 47 days! Others were negative in the feces, but positive in the throat swab.

    The study said that further studies are needed on the viability of infectivity of feces.

  • Classified? (Score:5, Informative)

    by hackingbear ( 988354 ) on Monday March 23, 2020 @12:33PM (#59863270)

    Grad that I actually read news media from China. These findings have been published by Chinese researchers on March 6 [medrxiv.org]:

    We found that at least 59% of infected cases were unascertained in Wuhan, potentially including asymptomatic and mild-symptomatic cases.

  • by buravirgil ( 137856 ) <buravirgil@gmail.com> on Monday March 23, 2020 @01:23PM (#59863456)
    The reasons for China's segregation from western media are not wholly addressed in terms of control, but protection.

    Repeated assertions of "contained" having a binary meaning are patently false when the teams of medical professionals, having halted a surging advance from the Hubei province, flew to Italy to repeat the challenge abroad. Dismissed as a PR "campaign" in western media, theirs is reactive and evolving medical procedure in action seeking empirical confirmation.

    The SCMP's coinage for asymptomatic transmission as "silent carriers" is simply aligning with western biases for an unedcated readership long after the fact was known to a minority of people sufficiently educated to trade in technical terms and specifications.

    For an un- or ill-informed audience there was no apparent contradiction of Trimp and Pence's performative claim their being tested was dependent on having shown symptoms for what an educated and tiny fraction of people knew to be the advance of a pathogen with asymptomatic character. A smaller still subset understood this "silent" or "ghost" characteristic was the principle challenge of the Party's failure to audit investigation into why a clinical physician was adamant his alarm was merited.

    What shame the Party might accept in this horror is errant in character, but what Trimp and Pence engage, with Britain's consultation, is state deceit.
  • by Hrrrg ( 565259 ) on Monday March 23, 2020 @01:53PM (#59863518)

    This article is a good and relatively reassuring read:

    https://www.newyorker.com/news... [newyorker.com]

    The portion most relevant to this discussion is here:

    "In South Korea, the success of mass testing in containing the spread of the disease has raised the possibility that asymptomatic carriers were causing outbreaks. But another implication of the experience in Singapore and Hong Kong is that these essentially invisible cases of the coronavirus may not be driving as many serious infections as some scientists have projected. Health officials there did not conduct mass testing of the population to look for infected people without symptoms. They focused on aggressively searching out and testing only those who developed suspicious symptoms or had high-risk exposures in the community. They accepted that the virus might circulate among people who notice nothing. Yet their strategy brought cases under control."

    So, asymptomatic carriers may not be much of a problem. I think we still have a lot to learn about this virus.

    • They focused on aggressively searching out and testing only those who developed suspicious symptoms or had high-risk exposures in the community. They accepted that the virus might circulate among people who notice nothing. Yet their strategy brought cases under control."

      My issue with this is a suggestion asymptomatic transmission is somehow one of category. In other words, COVID-19s virulence (for the most part) been sufficiently mild to become criticial in hosts with co-morbidities. Or as one terms it in the domain of insurance: pre-existing conditions.

      Exceptions within younger populations should halt interpretations such as yours in its tracks.

      A vector is a vector. If someone with mild- or a- symptomatic infection sheds COVID-19 and someone more susceptible picks i

  • by tbird20d ( 600059 ) on Monday March 23, 2020 @02:18PM (#59863612)
    One of the very, very few places to test 100% of the population is Vo, Italy, where they found that between 50% and 75% of those that tested positive for COVID-19 were asymptomatic at the time of testing. This article is in Italian, but Google translate seems to do a good job with the translation: https://www.repubblica.it/salu... [repubblica.it]
  • More than 43,000 people in China had tested positive for Covid-19 by the end of February but had no immediate symptoms, a condition typically known as asymptomatic, according to the data. They were placed in quarantine and monitored but were not included in the official tally of confirmed cases, which stood at about 80,000 at the time.

    Why would they NOT count these as Covid-19 cases? I don't see any really advantage to it. Sure, your total would look smaller, but who cares? Adding these would actually decrease the death/severe case rate. Of course, I don't understand anything the Chinese do at this point.

  • If you lose taste and smell it also attacks the brain, meaning we'll get stupider still.

  • In France, postal carriers will be limiting delivery of post and packages to 4 days a week and at the end of the months to 3 days, because of sick or quarantined carriers.

    So don't rely too much on online shopping, it might not last for long.

    Link to article, in French:

    https://www.lemonde.fr/economi... [lemonde.fr]

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