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science Wednesday 1 July 2020
‘Pooled testing’ for COVID-19 holds promise, pitfalls

infected into quarantine.
"If you are trying to do
something rapid, this ac-
tually prolongs the turn-
around time," Kraft said.
She and others also have
concerns about accuracy,
since test performance
tends to drop when screen-
ing in larger groups of peo-
ple where the targeted dis-
ease is less common.
"If we can't trust the test re-
sults then there's no point in
doing the test," said Jenni-
fer Nuzzo, of the Johns Hop-
kins University's Covid-19
Testing Insights Initiative.q

In this Friday, May 15, 2020 file photo, people line up for coronavirus testing at a large factory in Wuhan in central China's Hubei
province.
Associated Press
By MATTHEW PERRONE pooled testing may be University of Southern Cali- Nebraska's state health
AP Health Writer available for mass screen- fornia. Lakdawalla and laboratory used batch test-
WASHINGTON (AP) — The ings at schools and busi- colleagues estimate that ing with special permission
nation's top health officials nesses. pooled testing could save from the governor and the
are banking on a new ap- The principle is simple: In- schools and businesses FDA beginning in March.
proach to dramatically stead of running each per- between 50% and 70% on The lab's director said they
boost U.S. screening for the son's test individually, labo- costs. Under their model, had to stop several weeks
coronavirus: combining ratories would combine a group of 100 employees ago when their positive
test samples in batches in- parts of nasal swab sam- could be divided into 20 rate jumped to 17% with
stead of running them one ples from several people batches of five people. As- outbreaks at meat packing
by one. and test them together. A suming 5% of people carry plants.
The potential benefits in- negative result would clear the virus, only five pools Reserving pooled testing
clude stretching laboratory everyone in the batch. A would test positive, requir- for large groups with low
supplies, reducing costs positive result would re- ing individual testing. Ulti- rates of infection dovetails
and expanding testing to quire each sample to be mately, 45 tests would be with the government's in-
millions more Americans individually retested. Pool- needed for the pooled ap- creasing focus on people
who may unknowingly be ing works best with lab-run proach, versus 100 individu- without symptoms spread-
spreading the virus. Health tests, which take hours — al tests. ing the virus, especially
officials think infected peo- not the much quicker indi- But pooling won't always younger people.
ple who aren't showing vidual tests used in clinics or be the best option. Impor- "It's a really good tool. It
symptoms are largely re- doctor's offices. tantly, it won't save time can be used in any of a
sponsible for the rising num- The idea for pooling dates or resources when used in number of circumstances,
ber of cases across more from World War II, when it COVID-19 hot spots, such including at the community
than half of states. was considered for quickly as an outbreak at a nurs- level or even in schools," Dr.
"Pooling would give us screening blood samples ing home. That's because Anthony Fauci, the nation's
the capacity to go from a from U.S. draftees for syphi- the logistical and financial top infectious-disease ex-
half-a-million tests per day lis. Since then it has been benefits of pooling only pert, told a Senate hearing
to potentially 5 million in- adopted to screen blood add up when a small num- Tuesday.
dividuals tested per day," samples for HIV and hepa- ber of pools test positive. Still, health officials may
Dr. Deborah Birx, the White titis. And developing coun- Experts generally recom- have to convince some
House's coronavirus re- tries have used pooled mend the technique when key players to adopt the
sponse coordinator, told a samples to stretch testing fewer than 10% of people method. LabCorp, one of
recent meeting of labora- supplies. are expected to test posi- the nation's biggest testing
tory experts. China reported using the tive. About 7% of U.S. tests chains, said in an email that
For now, federal health reg- approach as part of a re- have been positive for the it is familiar with pooled test-
ulators have not cleared cent campaign to test all virus in the past week, ac- ing but currently believes
any labs or test maker to 11 million residents of Wu- cording to an AP analysis, "individual patient testing is
use the technique. The han, the city where the vi- though rates vary widely the most effective and ef-
Food and Drug Adminis- rus first emerged late last from place to place. For ficient way" to screen for
tration issued guidelines year. example, pooling would COVID-19.
for test makers in mid-June "Americans think this is some not be cost-effective in Dr. Colleen Kraft of Emo-
and wants each to first new concept because or- Arizona, where a surge has ry University worries that
show that mixing samples dinarily we don't have this pushed positive test results batched testing — with its
doesn't reduce accuracy, challenge of having to to over 22%. But the ap- multiple rounds of screen-
one of the potential down- stretch testing capacity," proach could make sense ing for some patients —
sides. said Darius Lakdawalla, a in New Jersey, with a posi- could slow test results, a
So it's not clear when health economist at the tivity rate under 2%. key factor for getting those