Fauci says states should consider pool testing for COVID-19

The nation's top infectious disease expert Dr. Anthony Fauci says states should consider adding a different testing strategy for COVID-19 known as “pool testing.” He says the White House Coronavirus Task Force is seriously considering it.

It’s a method that involves testing in batches verse individually. It can prove to be critical, especially now as some states are dealing with testing shortages. Experts say it can also prove to be a useful safety tool for colleges and universities that are preparing to welcome back some students. 

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“It is a good way for schools to be able to test a large number of their population and quickly get some idea of how prevalent the infection is. It shouldn't replace symptomatic testing so if you're feeling symptoms, you should be tested individually, but if you're doing a screening of your population, this is a good way to do it and get information in real-time,” said infectious disease expert and Johns Hopkins senior scholar Dr. Amesh Adalja. 

So how does pool testing work? 

People would still go in individually and get a coronavirus test, but in the lab, instead of testing each one, they would combine the specimens in small batches of maybe five, 10, or 15. Then they would run one test on all of them together

If that test is negative, then it's fair to say that batch of five, 10, or 15 people are all negative, but instead of utilizing 10 tests, they only used one, which saves resources. 

If the test comes back positive — then that’s when the lab would have to backtrack and re-test each specimen individually to find the infected person or persons. 

Mathematically, experts say you still save resources this way. 

“We’re doing really good right now, so at this point, we don't need in the (D.C.)and we're actually above the amount of testing we wanted to get to,” said Chris Geldart, D.C.’s Coronavirus Response Operations Chief. 

“When you combine multiple samples, you run the risk of sometimes decreasing sensitivity, so you may be diluting each individual sample which could mean you may have a lesser chance of detecting a positive. So that’s one of the cautions we have to balance,” said Dr. Jinlene Chan, Asst. Secretary Maryland Dept of Health.  

Dr. Chan has concerns about the possibility of "diluted" samples with this testing strategy. She says Maryland is looking into it, but has not rolled it out.

It’s also important that this testing strategy is done in a setting where the prevalence of infection is low, because if you're doing it in a place where high numbers of people are likely infected, then all your batches will be positive, and it won't serve its purpose.