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 Several academic laboratories and medical companies are rushing to
produce these blood tests, which can quickly identify
disease-fighting antibodies in people who already have been infected
but may have had mild symptoms or none at all. This is different
from the current, sometimes hard-to-come-by diagnostic tests that
draw on a nasal swab to confirm active infection.
“Ultimately, this (antibody test) might help us figure out who can
get the country back to normal,” Florian Krammer, a professor in
vaccinology at Mount Sinai’s Icahn School of Medicine, told Reuters.
“People who are immune could be the first people to go back to
normal life and start everything up again.”
Krammer and his fellow researchers have developed one of the first
antibody tests in the United States for COVID-19, the disease caused
by the new coronavirus. Krammer said his lab is busy distributing
key ingredients for the tests to other organizations and sharing the
testing procedure. He is transferring the work to Mount Sinai’s
clinical lab this week so it can begin testing patient samples.
Antibody tests won’t face the same bureaucratic hurdles diagnostic
testing initially did. The U.S. Food and Drug Administration relaxed
its rules last month, and body-fluid tests can proceed to market
without full agency review and approval.
Several private companies have begun selling blood tests for
COVID-19 antibodies outside the United States, including
California-based Biomerica Inc <BOAA.PK> and South Korean test maker
Sugentech Inc <253840.KQ>. Biomerica said its test sells for less
than $10 and the company already has orders from Europe and the
Middle East. Chembio Diagnostics Inc <CMI.O> of New York said it
received a $4 million order from Brazil for its COVID-19 antibody
test, and it plans a study of the test at several sites in the
United States.
Such tests are relatively inexpensive and simple, usually using
blood from a finger prick. Some can produce results in 10 to 15
minutes. That could make ramping up screening much easier than for
diagnostic tests.
Many questions remain, including how long immunity lasts to this new
virus, how accurate the tests are and how testing would roll out,
according to researchers and infectious disease experts. For now,
the number of people who have been able to fight off the virus is
unknown.
If testing goes forward on a wider scale, some public health experts
and clinicians say healthcare workers and first responders should
take priority.
Detecting immunity among doctors, nurses and other healthcare
workers could spare them from quarantine and enable them to keep
treating the growing surge of coronavirus patients, they say. It
could also bolster the ranks of first responders, police officers
and other essential workers who have already been infected and have
at least some period of protection from the virus, the experts say.
“If I ever get the virus and then get over it, I'll want to get back
to the front lines ASAP,” said Dr. Adams Dudley, a pulmonologist and
professor at the University of Minnesota School of Medicine. “I
would have a period in which I am immune, effectively making me a
‘corona blocker’ who couldn’t pass the disease on.”
'VERY ATTRACTIVE'
Other workers sidelined by lockdowns also could potentially return
to their jobs, providing a much-needed boost to the foundering U.S.
economy. The number of Americans filing for unemployment benefits
has soared, and business activity slumped to a record low this month
as the pandemic battered the manufacturing and service sectors.
Dr. William Schaffner, a professor of infectious diseases at the
Vanderbilt University School of Medicine, said companies, schools,
colleges and professional sports teams could all flock to these
tests. He also said a broad sample of testing could give a governor
or mayor enough confidence to lift certain restrictions on
businesses and schools if there is a strong level of immunity.
“These tests would be very attractive if they’re cost effective,
readily available and easy to do,” he said.
Tony Mazzulli, chief microbiologist with Toronto's Sinai Health
system, sounded a note of caution. It is uncertain whether
antibodies would be sufficient protection if a person were to be
re-exposed to the virus in very large amounts. That could happen in
an emergency room or intensive-care unit, for instance.
The timing of a return to work and normal life also matters, he
said. Some people who have antibodies to the virus could still be
contagious, even if their symptoms have eased. Patients begin to
make antibodies while they are still sick, Mazzulli said, and they
continue to shed the virus for a few days after they have recovered.
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It would be “a bit premature” to use the tests to make staffing decisions now,
Mazzulli said. “The hope is … (antibodies) do confer protection and they can go
to work, ride the subways, whatever they do. But there's no guarantee.”
Meantime, at the Mayo Clinic <MAYO.UL> in Rochester, Minnesota, researchers are
preparing to start a clinical trial in which patients who test positive for
COVID-19 would have their blood collected at the time of diagnosis, and again 15
to 20 days after that in the patient’s home.
The trial is designed to show when people who have COVID-19 infections
“seroconvert” - when antibodies produced by the body begin to show up in blood
tests. That information will be useful in determining the best time to conduct
the tests.
“You don't want to do it too soon because of the risk of false negatives,” said
Elitza Theel, director of Mayo’s Infectious Diseases Serology Laboratory.
Mayo also is evaluating the performance of antibody tests from several
companies, including two from China.
The U.S. Centers for Disease Control and Prevention said it is working on its
own version of antibody tests, but it has not given a timetable. The agency has
said extensive research is underway. One challenge for the CDC and other labs is
to get enough blood samples from people who have already been infected to verify
the antibody results.
The agency faced heavy criticism for sending a faulty diagnostic test to state
and local labs early in the coronavirus epidemic and then taking weeks to fix
it. The federal government is still trying to expand diagnostic testing
capacity.
MONTHS OF IMMUNITY
The potential for antibody testing arises as U.S. President Donald Trump is
considering scaling back “social distancing” and stay-at-home advisories in the
weeks ahead. His political allies argue that the toll on the U.S. economy is too
severe. About half of Americans have been ordered to shelter in place as many
schools and businesses remain shuttered indefinitely.
On Tuesday, Trump said: “I would love to have the country opened up and just
raring to go by Easter.”
Reopening offices and businesses without fear of triggering more infections,
however, has been complicated by the lack of testing to diagnose COVID-19 cases
across much of the country.
On Monday, Dr. Deborah Birx, a member of the White House coronavirus task force,
said simple, finger-prick antibody tests could play an important role, and she
suggested the federal government is not waiting on the CDC’s version.
“Some are developed now. We are looking at the ones in Singapore,” Birx said
Monday at a White House press briefing. “We are very quality-oriented. We don’t
want false positives.”
False positives are erroneous results that, in this case, could lead to a
conclusion that someone has immunity when he or she does not.
Researchers at the Duke-National University of Singapore Medical School said
they quickly developed one antibody test that had about 90% accuracy and later
introduced a more sophisticated version that was more reliable, according to a
report in the Straits Times of Singapore.
Infectious disease experts say immunity against COVID-19 may last for several
months and perhaps a year or more based on their studies of other coronaviruses,
including Severe Acute Respiratory Syndrome (SARS), which emerged in 2003. But
they caution that there is no way to know precisely how long immunity would last
with COVID-19, and it may vary person to person.
“You are likely to have immunity for several months,” said Dr. Stanley Perlman,
a professor of microbiology and immunology at the University of Iowa. “We just
don’t know. This is an incredibly important question.”
Perlman said many of the new antibody tests coming on the market now may be
highly effective, but researchers want to see data to back that up.
“You want them to be sensitive enough to detect everyone who has had the
infection,” Perlman said, “but not so nonspecific that you are picking up other
coronaviruses.”
(Chad Terhune reported from Los Angeles, Julie Steenhuysen from Chicago and
Allison Martell from Toronto; Editing by Julie Marquis)
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