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SCIENCE Thursday 14 May 2020
New coronavirus test is imperfect step toward mass screening

By MATTHEW PERRONE
AP Health Writer
WASHINGTON (AP) — A
new type of coronavi-
rus test offers a cheaper,
quicker way to screen for
infections, moving the U.S.
toward the kind of mass
screening that experts say
is essential to returning mil-
lions of Americans to school
and work.
But the first so-called an-
tigen test — announced
Saturday by the Food and
Drug Administration — is
not quite the kind sought
by top government health
officials. It is less accurate
than the current gold stan-
dard for testing and can
only be run on specialized
equipment.
"It is too early to tell," said
lab researcher Patricia Sim-
ner of Johns Hopkins Uni-
versity, assessing the test's
impact. "It certainly has
the potential to aid in more
widespread testing."
Some questions and an-
swers about the new test:
WHAT'S DIFFERENT ABOUT
THIS TEST?
The test from Quidel Corp.
screens for new infections
but in a different way. It This undated electron microscope image made available by the U.S. National Institutes of Health in February 2020 shows the Novel
looks for protein traces of Coronavirus SARS-CoV-2, the virus causes COVID-19. Associated Press
the virus — known as anti-
gens. The same approach
is used in rapid tests for flu, machine, but it only does performed without profes- seasonal flu. be more accurate, easier
strep throat and other in- one sample at a time. sional oversight or special "They are going to pick to use and more suitable
fections that are run at the WHY IS ANTIGEN TESTING equipment. While an im- up fewer people that are for mass screenings.
hospital or doctor's office. IMPORTANT? portant stepping stone, the infected," said Simner of OraSure Technologies has
They represent a trade-off, The U.S. is still struggling to Quidel test isn't there yet. Johns Hopkins. "So that's a $710,000 federal contract
sacrificing some of the ac- increase testing to the lev- HOW DOES IT WORK? where you see a lot of skep- to develop a saliva-based
curacy of more rigorous els that most public health The new test uses a nasal ticism around using antigen antigen test that could be
tests for quicker results at experts say are essential. swab like other screening tests for the diagnosis of performed at home. The
a lower cost. "They allow Harvard researchers have tests, and delivers results in COVID-19." company has antigen tests
you to dramatically ex- projected that the nation about 15 minutes. For now, Simner and other for other viruses — includ-
pand testing and they're needs to be able to do The sample is put in a tube experts say negative test ing HIV and Ebola — and
very cheap," said Dr. Scott 900,000 daily tests to be with testing chemicals and results for people showing those have accuracy rates
Gottlieb, the former FDA able to track new cases then into a cassette that symptoms should be con- of over 95%. Along with ac-
commissioner, in an inter- and contain new out- goes into the company's firmed with the more accu- curacy, the company is
view Sunday with CBS. But breaks as the country re- electronic reading device. rate genetic test. focused on speed, aiming
he acknowledged antigen opens. That's more than There, it's exposed to a test- "But as you might imagine, to delivers results in 20 to 30
testing's reduced accu- three times the country's ing strip embedded with that's not a perfect scenar- minutes.
racy: "They're going to miss current daily testing rate of laboratory-made antibod- io because you have to do "If you are going to test
some patients who have about 275,000. ies, the specific blood pro- twice as many tests when people coming into work
COVID." Previously, the only White House adviser Dr. teins made by the body's the result isn't positive," said you can't make them line
way to diagnose active in- Deborah Birx and other immune system when it Dr. Robin Patel of the Mayo up at 3 a.m." OraSure CEO
fections was a test that de- federal officials have said detects an infection. If the Clinic. Stephen Tang said. "You
tects the genetic material a "breakthrough" in anti- antigens and antibodies in- WHAT'S NEXT? need to be able to get
of the virus. While highly ac- gen testing could open the teract, the test is positive. Many companies are work- their results quickly."q
curate, most of those tests way to daily testing before HOW ACCURATE IS THE ing on versions that would
take hours to develop on going to back to work or TEST?
machines mainly found at school. The new test is expected
commercial labs, hospitals The National Institutes of to detect about 80% of ac-
or universities. Abbott Lab- Health is pouring $1.5 bil- tive COVID-19 infections,
oratories makes a 15-min- lion into efforts to develop according to the FDA. That
ute version of the genetic highly accurate, easy-to- accuracy rate is similar to
test that runs on its portable use tests that could be other rapid antigen tests for linda.reijnders@cspnv.com