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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: -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?

    Starting Score:    0  points
    Moderation   -1  
       Troll=1, Total=1
    Extra 'Troll' Modifier   0  

    Total Score:   -1  
  • (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%