A $5 rapid test for the coronavirus may be nearly as
effective as the slower, more complex polymerase chain
reaction test for identifying people who may spread the
coronavirus, a novel experiment has found. The study,
conducted by scientists at the University of California,
San Francisco, is among the first head-to-head comparisons
of a rapid test and the P.C.R. diagnostic tool under
real-world conditions. But the number of participants was
comparatively small, and the data have not been
peer-reviewed or published. A rapid test still cannot
conclusively determine that an individual is not infected;
the tests are intended primarily to detect the presence of
high levels of the virus, rather than its absence, and are
authorized only to evaluate symptomatic people. At the
moment, anyone who has been exposed to the virus should be
tested by P.C.R., said Joseph DeRisi, an infectious
disease expert at U.C.S.F. and a co-leader of the project.
Still, the finding offers hope that rapid tests can be
used even more widely to help contain a pandemic that is
resurging in the United States. Some epidemiologists have
argued that the country relies too heavily on cumbersome
P.C.R. tests for screening even as the coronavirus flies
through communities.
Jim Wilson/The New York Times
The new test, Abbott’s BinaxNOW, offers results in 15
minutes, compared with the days or weeks people may have
to wait for a P.C.R. result. The Trump administration
already has
purchased 150 million BinaxNOW tests and plans to ship them to states for use in schools,
nursing homes and meatpacking plants. The tests could also
be used to screen people in communities where time, trust
and resources are in short supply. The study assessed the
BinaxNOW in one such community, a largely Latino
neighborhood in San Francisco. On three mornings in late
September, as commuters emerged from a BART train station
in the Mission District, they were offered two nasal
swabs: one for a P.C.R. test, the other for the rapid test
with a simple readout. The commuters received only the
P.C.R. result, by text, but the researchers compared both
tests. Of the 878 people who took the tests at the train
station, only 26 tested positive on the researchers’
P.C.R. BinaxNOW identified only 15 of them.
researchers’ P.C.R.
But when they only considered P.C.R. results that
corresponded to high viral loads, the researchers found
that the BinaxNOW test detected 15 of the 16 people who
were most likely to transmit the virus. “This card will do
pretty well at detecting the most infectious people, the
people who are actually spreading virus,” Dr. DeRisi said,
referring to the BinaxNOW. “On the whole, I’m pretty
encouraged and very optimistic.”
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