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COVID-19 Testing: What You Need to Know

Updated: Nov 6, 2020

Source: https://www.wayneunc.org/wellness/health-talk-blog/health-talk/2020/covid-19-testing-need-know/


If you’ve experienced symptoms of what could be coronavirus infection, knowing if you’re infected can help protect not only your health, but the health of those around you.

“There has been some confusion over what it takes for a patient to get testing for COVID-19,” said Dr. Dave Tayloe Jr., Pediatrician with Goldsboro Pediatrics. “If your symptoms are manageable, your primary care provider is a good place to start.”

Dr. Tayloe also serves on the North Carolina Institute of Medicine Steering Committee to develop the state plan for implementing a COVID-19 immunization program.


COVID-19 Testing

There are three types of tests available for COVID-19:

  • Molecular and antigen tests for determining whether you are currently infected with COVID-19

  • Antibody (serology) tests, which determine whether you had COVID-19 recently

Molecular Tests

Molecular tests are considered the gold standard diagnostic test for COVID-19, and the ones most widely used in our community.

“This is the test you’ve probably heard about. A health care provider will insert a 6-inch long swab into one of your nostrils, rotating it deep into the back of your nasal passage – for about 15 seconds,” said Dr. Tayloe. “They will then repeat the process in the other nostril, insert the swab into a container, and send it off for testing.”

Molecular tests are considered the gold standard, because studies show these tests to be the most reliable when patients first begin showing symptoms, according to Dr. Melissa Miller, Director of the Clinical Microbiology and Molecular Microbiology Laboratories for UNC Health Care.

With molecular tests, you can typically expect results within 24-48 hours. The test uses a technique called reverse transcription polymerase chain reaction, or RT-PCR, where genetic material from your specimen is copied and compared to the genetic sequence of the COVID virus.

Antigen Tests

The antigen test is another test designed to determine whether you are currently infected with coronavirus.

“An antigen test is faster, but it is also less sensitive than the molecular test,” said Dr. Tayloe. “With an antigen test, you run a higher chance of seeing a false negative. This is when your test says you do not have COVID-19, but you are actually infected with the virus.”

Your healthcare provider will take a nasal or throat swab, similar to the molecular test. The provider will then place the swab into a tube with special chemicals that expose the proteins. The sample is then dispensed into a cassette that is placed into the testing device to get your results.

Antigen tests work by testing the proteins on the surface of the virus. When you hear doctors refer to rapid tests, they are referring to antigen tests, which provide results in about 15 minutes.

“If your antigen test comes back positive, it’s very likely that you have the virus,” said Dr. Tayloe. “If you have a negative result, your doctor may want to confirm that result using a molecular test.”

Due to limited supplies and reliability of results, providers are not routinely administering antigen tests in our area.

Antibody Tests

An antibody test can help determine if you’ve had COVID-19 recently, but it isn’t designed to diagnose a current infection.

Also called a serological test, the antibody test relies on detecting antibodies in a blood sample, usually from a simple finger prick or blood draw.

When you’re exposed to the COVID virus, your body develops antibodies over several days or a week. Antibodies are proteins your body makes when it mounts a response against viruses. If your blood contains antibodies for COVID-19, you may have had recent exposure to the virus.

Serological tests usually offer faster results than molecular tests, but the FDA is less certain of their accuracy.

“We’re still learning about the immune system’s antibody response to coronavirus,” said Dr. Tayloe. “For example, we don’t know how accurate these tests are for people who are asymptomatic or have mild symptoms, since their immune response can be different from that of people with severe illness.”

Antibody tests may be available during community blood drives or from your physician.

Positive Results

If you had a positive antigen or molecular (PCR) test for COVID-19, you’ll need to self-quarantine for 14 days, according to the U.S. Centers for Disease Control (CDC). During self-quarantine, you should stay inside your home – apart from other people in your household – and only leave home for medical care.

“If you have symptoms, or you’ve come in close contact with someone who has been diagnosed with COVID-19, you should start self-quarantining after you get tested and until you get your results,” said Dr. Tayloe. “Some tests can take a little longer to process. You want to make sure you’re keeping those around you safe.”

Close contact is defined as 15 or more minutes of exposure at less than six feet with a person who has been proven to be infected with COVID-19.

About 80% of patients with COVID have mild to moderate disease and can be managed at home, according to Dr. David J. Weber, Medical Director of Infection Prevention at UNC Hospitals.

If you have questions or concerns about your symptoms or need follow-up care, call your doctor. If your symptoms are severe, go to your nearest emergency room.

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