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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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