8 ms·

Austria has just published the results of their first representative study on about 1500 randomly selected people [1]. They found 0.33% infection rate (confiden

• MikeAmelung 7y ago
  I don't think this rules anything out, because this study was done on throat swab PCR tests. It's entirely possible a much larger percentage of the people in this study had already been exposed and cleared the virus. Not saying that IS the case, just saying it's entirely possible.
  • fsh 7y ago
    I don't see how this theory would be compatible with the rapid rise in hospitalizations and deaths that was observed in the last weeks. If many people had been infected a long time ago, why are they only now starting to get sick?
    • heartbreak 7y ago
      There's a logical inconsistency here. If we assume that the total number of cases is much higher than reported, then the hospitalization rate per infection is driven down by the larger denominator. There's a point at which there are so many total cases that the number of hospitalizations is problematic and noticeable. If we continue to assume that the total number of cases is much higher than reported, the death rate per infection (IFR) is also driven down by the larger denominator.
      • anonymouz 7y ago
        But if we had a large number of undetected cases in the past, then we should also have a large number of undetected cases now, contrary to the study. (Unless we already have herd immunity, but there is no data at all suggesting this.)
    • MikeAmelung 7y ago
      I'm not necessarily saying people got infected a long time ago. If anything I think we're just missing way more cases than people assume at this point.
    • thehappypm 7y ago
      Perhaps in the past, earlier in the virus's exponential growth, many people had it but still an order of magnitude less than now. And that order of magnitude is the difference between a slammed hospital and a regular day. And because an order of magnitude people less had it, groups like the elderly were an order of magnitude less likely to be exposed en mass.
  • leereeves 7y ago
    Also, according to [1], only a third of throat (pharyngeal) swabs from patients known to have the virus were positive. 1: https://www.jwatch.org/na51116/2020/03/17/pharyngeal-and-nasal-swabs-may-not-have-adequate https://www.jwatch.org/na51116/2020/03/17/pharyngeal-and-nas...
    • heartbreak 7y ago
      Given how difficult it is to get a test in many US states, the high number of reported negative test results should be surprising.
  • maxerickson 7y ago
    There's some places doing blood testing and it looks like it is going to be about the same: https://www.sanmiguelcountyco.gov/590/Coronavirus https://www.sanmiguelcountyco.gov/590/Coronavirus Very few positive PCR tests, very few positive blood tests, so not as interesting as blood tests in a region with more positive PCR tests, but it demonstrates there's not a big group of people in the county that have immunity.
    • bwb 7y ago
      Just a note, no evidence of how much immunity yet. We are hoping that is the case but there are also a few loose stories of people getting covid a 2nd time. We should know more in a few weeks to a month...
      • Reason077 7y ago
        There are a few reports of people returning a positive test a second time. That is not the same thing as getting infected a second time.
        • maxerickson 7y ago
          The blood test looks for antibodies, so it detects whether the person has had an immune response to the virus. The GP is pointing out that having an immune response to a first infection has not been riguorsly demonstrated to prevent future infection. If we are unlucky, immunity may only persist for a short period of time.
          • DanBC 7y ago
            Which blood test currently in use looks for antibodies?
            • maxerickson 7y ago
              It's explained on the page I linked earlier in the thread. A founder of the company that developed it is paying to have the county where he lives tested.
  • ajross 7y ago
    A giant outbreak that had already passed weeks ago would be inconsistent with the shape of the curve of symptomatic cases, though. We know for sure that the bulk of people who have ever had this disease are still sick
    • heartbreak 7y ago
      The bulk of people who got sick enough to get tested and/or go to the doctor are still sick. Remember, the hypothesis is that there are a large number of infections mild enough to not be reported, tested, or hospitalized.
      • ajross 7y ago
        Yes, but if they are the same disease, then the asymptomatic/symptomatic fraction of cases must be the same over time[1]. So a bunch of people who had the disease asymptomatically weeks ago should have shown up in a spike of people with symptoms, and it didn't. [1] Or if they weren't, that would be a BIG result and very surprising. It's absolutely not something you can assume to make an argument.
        • guscost 7y ago
          Pathogens evolve: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463 https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr...
          • ajross 7y ago
            Actually SARS-CoV-2 has been found to have a comparatively low mutation rate. But my point was that now you're not just positing a very large undetected outbreak of COVID-19, you're positing a very large undetected outbreak of an itself-undtected variant strain of COVID-19 that just happens to have the properties needed to produce the overmeasurement that you want to see in the case fatality rate. See the problem with that logic?
            • 7y ago
• indecisive_user 7y ago
  Correct me if I'm wrong, but this used PCR testing to determine the number of _currently_ infected people. It says nothing about the number of people that _were_ infected, but fought off the virus and are now potentially immune.
  • coldcode 7y ago
    I think that requires an antibody test
    • fsh 7y ago
      Indeed PCR tests only test for the presence of the virus itself. Their big advantage is an extremely high specificity. Antibody tests are plagued by large numbers of false positives.
  • Retric 7y ago
    Simple exposure is not enough to become immune. You need a significant infection which triggers a strong immune system response to build long term immunity. Thus in the initial stages of an outbreak you can basically ignore people that became infected weeks ago, had a significant infection, and are now immune due to the exponential growth curve. It’s only after the rate of infection stayed the same or falls for a month+ that you need to adjust for such people.
    • indecisive_user 7y ago
      >You need a significant infection which triggers a strong immune system response to build long term immunity. I don't think this is true. I get the flu shot every year and have never had a strong immune response to it, yet I'm still immune to the major flu strains each year. Point being, it's possible for your body to create long term immunity to a virus without suffering from a severe infection.
      • Retric 7y ago
        I am specifically referring to COVID-19 where we don’t have a vaccine. Vaccines fake a significant infection to get that same strong immune response. This is also why some vaccines require multiple doses over a short period.