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Antigen Testing Now Available from BestMed Urgent Care

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BestMed Urgent Care is now offering the Sofia 2 SARS Antigen FIA rapid point-of-care test for the detection of COVID-19 to symptomatic and asymptomatic patients that have had contact exposure. The antigen test is available in BestMed’s Urgent Care’s service areas of Lane, Linn, Douglas, and Gallatin Counties. Antigen tests are critical to the overall response against COVID-19 as they can be produced at a lower cost than polymerase chain reaction (PCR) antibody tests, and accelerate the time to diagnosis and potential treatment of COVID- 19 for the patient.

The Sofia 2 is the first antigen test authorized by the Food and Drug Administration (FDA) under its Emergency Use Authorization (EUA) to quickly detect proteins from the virus that causes COVID-19 in respiratory specimens such as nasal swabs. Test results may be provided within 15 minutes using this methodology.

What Does the Antigen Test’s Authorization Under the FDA’s EUA Mean?

When there are no FDA-approved or cleared tests for a virus available and other criteria are met, the FDA can make tests available under an emergency access mechanism called an EUA. The EUA for this test is supported by the Secretary of Health and Human Service’s (HHS’s) declaration that circumstances exist to justify the emergency use of in vitro diagnostics (IVD) for the detection and/or diagnosis of the virus that causes COVID-19. This EUA will remain in effect (meaning this test can be used) for the duration of the COVID-19 declaration justifying emergency use of IVDs unless it is terminated or revoked by the FDA.

What is the Difference Between an Antigen Test and an Antibody Test?

BestMed has also been providing the PCR antibody test to area patients for the past several weeks. While the PCR test can be incredibly accurate, running the tests and analyzing the results takes time. The PCR is a molecular test that detects genetic material from the virus. Antigen tests, like the Sofia 2 SARS Antigen FIA, detect proteins from the virus within minutes. Antigen tests are highly specific for the virus. Still, they are not as sensitive as molecular tests, which means that a positive result is highly accurate, but a negative result does not rule out infection.

More specifically:

Regarding Antigen Tests:

  • An antigen is a molecule or structure present on the outside of a pathogen
  • Antigen tests are typically used for early identification of an active infection in symptomatic patients
  • These tests identify the virus through detection of nucleoproteins, similar to influenza tests
  • Viral antigens can often be detected in samples taken from nasal passages and the throat
  • The U.S. Centers for Disease Control and Prevention (CDC) recommends using a test that detects the SARS-CoV-2 virus, such as one that checks respiratory samples to test for active infection.

Regarding Antibody Tests:

  • Antibodies are proteins that the body’s white blood cells produce to fight infection, which may remain in the blood long after the infection clears
  • Antibody tests identify active (IgM) or past (IgG) infections by looking for antibodies against the specific virus
  • Antibody tests look for exposure to a pathogen resulting in the generation of an immune response, e.g., increase in IgG/IgM antibodies; the immune response may take days or weeks to appear in a serology assay post-exposure
  • Antibodies are typically detected in blood samples; either whole blood or serum/plasma
  • Antibody tests typically cannot diagnose the disease immediately after exposure, as antibodies may take one to three weeks to develop
  • A positive antibody test indicates that a person had an immune response to SARS-CoV-2 regardless of the presence of symptoms
  • Whether antibodies may indicate immunity to further infection is still being investigated by the healthcare community

If I Believe I Have Been Exposed to COVID-19, Why Should I Obtain the Antigen Test?

If you test positive, the results, along with other information, can help your healthcare provider make informed recommendations about your care, and the test results may help limit the spread of COVID-19 to your family and others in your community.

Are There Potential Risks of Receiving the Sofia 2 SARS Antigen FIA Test?

Possible side effects include potential mild discomfort or other complications that can happen during sample collection. As an additional risk factor, the test may produce an incorrect test result.

What Does it Mean if I Receive a Positive Antigen Test Result?

If you receive a positive test result, you have likely contracted COVID-19 because proteins from the virus that causes COVID-19 were found in your sample. Therefore, it is also likely that you may be placed in isolation to avoid spreading the virus to others. There is a small chance that this test can give a positive result that is wrong (a false-positive result). Your healthcare provider will work with you to determine how best to care for you based on your test results, along with your medical history and symptoms.

What Does it Mean if I Receive a Negative Antigen Test Result?

A negative test result means that proteins from the virus that causes COVID-19 were not found in your sample. This test can give a false-negative result in some individuals with COVID-19, which means that you could still have COVID-19 even though the test is negative. If your test result is negative, your healthcare provider will consider the test result together with all other aspects of your medical history in deciding how to care for you.

If your test result is negative, you should discuss with your healthcare provider whether an additional PCR test would help with your care, and when you should discontinue home isolation. If you do not have an additional test to determine if you are infected and may spread the infection to others, the CDC currently recommends that you should stay home until three things have happened:

  • You have had no fever for at least 72 hours (without the use of medicine that reduces fevers); and
  • Other symptoms have improved; and
  • At least seven days have passed since your symptoms first appeared.

For more information, refer to the CDC’s guidance on how to prevent the spread of COVID-19 if you are sick.

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