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posted by martyb on Sunday November 22 2020, @03:43AM   Printer-friendly
from the down-for-the-count? dept.

Frequent, rapid testing could cripple COVID-19 within weeks, study shows: Research shows test turnaround-time, frequency far more important than sensitivity in curbing spread:

Testing half the population weekly with inexpensive, rapid-turnaround COVID-19 tests would drive the virus toward elimination within weeks—even if those tests are significantly less sensitive than gold-standard clinical tests, according to a new study published today by CU Boulder and Harvard University researchers.

Such a strategy could lead to "personalized stay-at-home orders" without shutting down restaurants, bars, retail stores and schools, the authors said.

"Our big picture finding is that, when it comes to public health, it's better to have a less sensitive test with results today than a more sensitive one with results tomorrow," said lead author Daniel Larremore, an assistant professor of computer science at CU Boulder. "Rather than telling everyone to stay home so you can be sure that one person who is sick doesn't spread it, we could give only the contagious people stay-at-home orders so everyone else can go about their lives."

[...] They then used mathematical modeling to forecast the impact of screening with different kinds of tests on three hypothetical scenarios: in 10,000 individuals; in a university-type setting of 20,000 people; and in a city of 8.4 million.

[...] When it came to curbing spread, they found that frequency and turnaround time are much more important than test sensitivity.

For instance, in one scenario in a large city, widespread twice-weekly testing with a rapid but less sensitive test reduced the degree of infectiousness, or R0 ("R naught"), of the virus by 80%. But twice-weekly testing with a more sensitive PCR (polymerase chain reaction) test, which takes up to 48 hours to return results, reduced infectiousness by only 58%. When the amount of testing was the same, the rapid test always reduced infectiousness better than the slower, more sensitive PCR test.

That's because about two-thirds of infected people have no symptoms and as they await their results, they continue to spread the virus.

"This paper is one of the first to show we should worry less about test sensitivity and, when it comes to public health, prioritize frequency and turnaround," said senior co-author Roy Parker, director of the BioFrontiers Institute and a Howard Hughes Medical Institute investigator.

Journal Reference:
Daniel B. Larremore, Bryan Wilder, Evan Lester, [et al]. Test sensitivity is secondary to frequency and turnaround time for COVID-19 screening. Science Advances, Nov. 20, 2020; DOI: 10.1126/sciadv.abd5393


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  • (Score: 5, Interesting) by c0lo on Sunday November 22 2020, @07:02AM (10 children)

    by c0lo (156) on Sunday November 22 2020, @07:02AM (#1080376) Journal

    The results of a precise test can be obtained in 24h or less if the pressure on the labs don't overflow their capacity. Worked a charm in Melbourne case.

    Took 111 days in which 75% of Melbournians stayed at home (and would have taken 2-3 weeks less if not for an idiot that lied the contact tracers and started two new clusters), but the results are wonderful - today's 3 weeks+ with 0 community cases and 0 deaths, we were announced no masks required outdoors if not in a crowd, restaurants allowing 150 people indoor (up from 30). We keep it like this for 1 more week, we get over the epidemiological threshold of 28 days and we'll likely have as close a normal Christmas as possible (i.e. keep an ear to the news, just in case some other unfortunate mistake let the virus escape from the repats quarantine).

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0
    Starting Score:    1  point
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    Extra 'Interesting' Modifier   0  
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  • (Score: -1, Troll) by Anonymous Coward on Sunday November 22 2020, @02:22PM (5 children)

    by Anonymous Coward on Sunday November 22 2020, @02:22PM (#1080433)

    here's by totally forgoten math:
    so 10% is super. we can map outcomes to digits 0 - 9.
    only one digit (10%) is interesting.
    so let's map this case to the digit "1". (win!) all others map to lose.
    now let's combine all possible combinations:
    0000000
    0000001
    ...
    9999999
    so we get 10 million combinations.
    let's see how many have a "1" and only one "1":
    1000000
    0100000
    0010000
    ...
    0000001
    so there are 7.
    so 7 devide by 10 million is the probability for 10% in 7 series?

    • (Score: -1, Redundant) by Anonymous Coward on Sunday November 22 2020, @02:55PM

      by Anonymous Coward on Sunday November 22 2020, @02:55PM (#1080442)

      oops.
      tbc ... remove one placeholder, so to account for "only one one" so 6 placeholders instead of 7.
      also the digit "1" is not usable, only "9" digits are available so
      count with "9" symbol to 6 placeholders
      9^6 = 531'441
      multiply all of 'em 531'441 unique symbol string made up of 9 unique symbols in 6 placeholders by 7 (7 places where a "1" could be and get 3'720'087.
      (100 x 3'720'087) devide by all possible symbolstring with 10 symbols and 7 placeholders (10'000'000) and get ... 37.20087?

    • (Score: 2) by c0lo on Sunday November 22 2020, @05:04PM (3 children)

      by c0lo (156) on Sunday November 22 2020, @05:04PM (#1080456) Journal

      let's see how many have a "1" and only one "1":

      Why "only one 1"? Should've been "at least one 1".

      1000000
      0100000
      0010000
      ...

      And why all the others digits are suddenly mapped on "0"? Even if the outcome is the same, if you mapped probabilities to 9, then you must use it to compute the number of cases.

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0
      • (Score: 0) by Anonymous Coward on Sunday November 22 2020, @09:48PM (2 children)

        by Anonymous Coward on Sunday November 22 2020, @09:48PM (#1080498)

        i thought the original "homework" was rolling a 10 side dice with only 1 green side (all others being red) for a total of 7 times; what are your chances to get one and only one green.
        anyways ... i was assuming no one wants green (not even once), cause that means you gotta stay home for two weeks?
        so what's the correct number then?

        • (Score: 2) by c0lo on Sunday November 22 2020, @10:31PM

          by c0lo (156) on Sunday November 22 2020, @10:31PM (#1080502) Journal

          To get "at least one green". Go check.

          Homework: if the probability of getting a false positive is 10%, what is the probability after 7 tests to get at least one false positive**?

          --
          https://www.youtube.com/watch?v=aoFiw2jMy-0
        • (Score: 0) by Anonymous Coward on Monday November 23 2020, @03:34AM

          by Anonymous Coward on Monday November 23 2020, @03:34AM (#1080552)

          1 - (1 - 0.10) ^ 7 = 0.521703
          ie. 52%

  • (Score: 0) by Anonymous Coward on Sunday November 22 2020, @09:15PM (3 children)

    by Anonymous Coward on Sunday November 22 2020, @09:15PM (#1080492)

    Took 111 days in which 75% of Melbournians stayed at home

    Meanwhile in Latvia, all summer new infections were in the single digits with NONE of that craziness. Magic?

    • (Score: 3, Informative) by c0lo on Sunday November 22 2020, @10:35PM (2 children)

      by c0lo (156) on Sunday November 22 2020, @10:35PM (#1080503) Journal

      Well, while Latvia [www.latvia.travel] were "all summer", we were "all winter". Magic?

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0
      • (Score: 0) by Anonymous Coward on Monday November 23 2020, @01:39AM (1 child)

        by Anonymous Coward on Monday November 23 2020, @01:39AM (#1080535)

        Well, while Latvia [www.latvia.travel] were "all summer", we were "all winter". Magic?

        Dude, the weather in what is called "winter" in Australia is a bit warmer than what is summer in Latvia (should you not know that already, as a professed ex-European?) It is rather to be expected for the respiratory illnesses there to peak differently.

        Like in this report from 2019: https://globalnews.ca/news/5435232/australia-flu-season-canada/ [globalnews.ca]
        "Usually, flu season doesn’t start until June or July, Booy said. This year, numbers started to pick up in mid-March."

        Now, looking at Australian COVID peaks of 2020, I observe end of March and end of July. Isn't the nature predictable?

        • (Score: 2) by c0lo on Monday November 23 2020, @03:17AM

          by c0lo (156) on Monday November 23 2020, @03:17AM (#1080550) Journal

          Dude, the weather in what is called "winter" in Australia is a bit warmer than what is summer in Latvia

          Do tell. Really? I wonder how I didn't notice. Perhaps because in winter Aussies gather in closed spaces too.

          Now, looking at Australian COVID peaks of 2020, I observe end of March and end of July. Isn't the nature predictable?

          Go ahead, mate, your ability to predict nature should make you rich in no time.

          --
          https://www.youtube.com/watch?v=aoFiw2jMy-0