US May Shift Strategy on COVID Testing

'Pool testing' may be more effective
By John Johnson,  Newser Staff
Posted Jun 26, 2020 9:53 AM CDT

(Newser) – The US is considering a major shift in strategy in regard to COVID-19: It's called "pool testing." The general idea is to make testing more efficient by taking a shortcut of sorts. Samples would be taken from a group of people and then combined, and then one test would be used for the entire group. Only if it comes back positive would people in the group be tested individually. Details and coverage:

  • Fauci: Dr. Anthony Fauci tells the Washington Post that "intense discussions" are underway among US health officials about adopting the practice where possible. Why? "Something's not working," he says of the current testing strategy. "I mean, you can do all the diagramming you want, but something is not working."

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  • More efficient: "Pooling would give us the capacity to go from a half a million tests a day to potentially 5 million individuals tested per day," Dr. Deborah Birx of the White House coronavirus team told the American Society for Microbiology during a virtual conference this week, reports STAT News.
  • An example: Scientific American provides an example of how this works. Let's say a warehouse wanted to test 100 people. Instead of running diagnostic tests on all 100 individuals, they'd be divided into five groups of 20. "That gives you five pools with 20 samples, and you use one test per pool," the magazine notes. "If the first four sample pools test negative, you have eliminated 80 people with four tests. If the last pool tests positive, you retest each sample in that last pool individually to identify the one with the disease. In the end, you did 25 tests instead of 100."
  • A catch: Pool testing is a "numbers game," notes SA, and it would work best in areas where you'd actually expect most people to test negative. That is, if too many of the pools test positive, that defeats the whole point of trying to make the testing more efficient. "You wouldn't want to be doing it right now in Texas, but you could do it in Massachusetts," Paul Sax, an infectious disease specialist, tells STAT.
  • Bigger picture: Pool testing is about identifying asymptomatic or presymptomatic people in areas where officials weren't aware the virus was in circulation. That way, authorities could use aggressive contact tracing as a way to prevent bigger outbreaks, says Birx.
  • Logistics: Labs already are working on ways to pool samples, and Medical News Today has specifics on an approach being used in Germany. The idea is about "trying to do more with the same number of tests," says Tomer Hertz of Ben-Gurion University of the Negev in Israel, which is also working on the process.
(Read more COVID-19 stories.)

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