By Katherine Hoyer, Panhandle Health District
and Andrea Nagel, Kootenai Health
Reports in national media lately have been all
about antibody testing (also known as serologic testing) and the excitement of
being one step closer to understanding the total impact of COVID-19. This news
is hopeful and encouraging, but where are we at in our area?
A common anecdote we hear is, “I think I had
COVID-19 a few months ago. I was never tested, but could I have immunity proven
through the antibody test?”
There is important value in understanding
individual immunity as well as potential herd immunity among our community.
With the science on COVID-19 still evolving, there is a lot we need to
learn about antibody tests and how well they can help us answer our questions.
“Serologic testing has the potential to
provide a powerful tool in the management of the COVID-19 pandemic,” Michael
Harvey, M.D., medical director of Laboratory Services at Kootenai Health, said.
“This testing methodology will play a vital role in assessing how prevalent the
disease actually is.”
Here is some information from the FDA on
serological testing.
How
the Test Works
Unlike
a test designed to diagnose an active COVID-19 infection (specifically from the
SARS-CoV-2 virus), serological tests can help identify individuals who have
developed an immune response to the virus, either as part of an active
infection or a prior infection. The test detects the presence of antibodies in
the blood – if antibodies are present, that indicates that the person has been
exposed to the virus and developed antibodies against it, which may mean that
person has at least some immunity to the virus. In the early days of an infection
when the body’s immune response is still building, antibodies may not be
detected, which is why serological tests should not be used as the sole basis
to diagnose or exclude infection with the SARS-CoV-2 virus.
There
is still a great deal about COVID-19 immunity that we don’t yet fully
understand. For example, we don’t yet know that just because someone has
developed antibodies, that they are fully protected from reinfection, or how
long any immunity lasts. We do expect that data from more widespread serological
testing will help us track the spread of the virus nationwide and assess the
impact of our public health efforts now, while also informing our COVID-19
response as we continue to move forward. Determining the next steps in our
response to COVID-19 is partially dependent on an accurate assessment of our
national efforts thus far, and the quality of data for making this decision is
dependent on accurate testing products.
How reliable are the tests?
Most antibody tests have not been sufficiently
evaluated to know how reliable they are. The Infectious Disease Society of
America advises that antibody test results should not be used to make staffing
decisions or decisions regarding the need for personal protective equipment.
Because of the COVID-19 emergency, the FDA has
allowed serology tests to be marketed based on the manufacturer’s evaluation
only and without the usual FDA evaluation – few serology tests have been evaluated by the FDA
at this time.
“Within the past several weeks, multiple
companies have introduced rapid point-of-care testing kits for the detection of
antibodies against COVID-19,” Dr. Harvey said. “We’ve see fundamental
reliability issues with many of these tests. Because this is a new virus, there
is no gold standard to serve as a comparison to these new tests. One common
issue is cross-reactivity with non-COVID-19 coronaviruses, such as the virus
that causes the common cold or the one that causes SARS. This means a positive
antibody test could be detecting antibodies from the wrong coronavirus, a false
positive.”
FDA is currently working with the National
Institutes of Health (NIH) and the Centers for Disease Control and Prevention
(CDC) to evaluate serological tests. Dr. Harvey and other medical leaders in
our community are monitoring developments and will continue to provide guidance
on the issue. He said as soon as a reliable test is available, he and his team
will organize a plan to implement serologic testing in our community.
What else can you do to help?
According to the FDA, if you have fully
recovered from COVID-19, you may be able to help patients currently fighting
the infection by donating your plasma. Because you fought the infection, your
plasma now contains COVID-19 antibodies. These antibodies provided one way for
your immune system to fight the virus when you were sick, so your plasma may be
able to be used to help others fight off the disease.
Several
resources are available regarding options to donate convalescent plasma. To
learn more and find the site nearest you visit:
·
COVIDPlasma.org
·
America’s Blood Centers
·
American Red Cross
·
Blood Centers of America
·
CoVIg-19 Plasma Alliance
·
National COVID-19 Convalescent Plasma
Project
·
Plasma Protein Therapeutics Association
Kootenai Health and the Panhandle Health District are
actively working to share information about COVID-19 with our community. You
can find the latest updates and ways to protect yourself at cdc.gov/covid19. If you have questions about
COVID-19 or think you may have the virus, call the Panhandle Health District
COVID-19 hotline at 1-877-415-5225.
