Your Guide to Testing for Active Coronavirus Infection

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Woman getting a nasal swab; Guide to Testing for Active Coronavirus

Diagnostic testing for active COVID-19 is confusing. Not only are there different types of tests, health care professionals can get samples by swabbing different areas – from your nose, mouth, throat and more. Dr. Rossana Rosa, Infectious Disease Specialist for UnityPoint Health, helps us understand your current testing options and why it’s important for you to know the latest testing developments.

Which COVID-19 Test Should I Get?

There are two diagnostic tests that identify active COVID-19 infection in people. A third type of test, an antibody test, works to find evidence you’ve previously had COVID-19.

How Do Antigen Tests for COVID Work? 

An antigen test detects proteins produced by the virus. These tests are less sensitive and often less accurate. Antigen tests are performed with nose or throat swabs to search for an active COVID-19 infection.

How Do Molecular COVID Tests Work? 

A molecular test includes the rt-PCR test, commonly called PCR test. Molecular tests detect the genetic material that makes up the virus. These tests are very sensitive and often more accurate. Molecular tests look at samples from the nose, saliva, sputum (saliva and mucus) or nasopharyngeal (area right past your nostril) to search for an active COVID-19 infection.

“Molecular tests pick up very small fragments of the virus, even beyond the point that someone is contagious or ill, but, perhaps, you are still sheading the virus. That’s why you can get a positive test result from a molecular test, even though you might not have an active COVID-19 infection.” Dr. Rosa says.

How Do Antibody COVID Tests Work? 

An antibody test does not test for active COVID-19 infection. Instead, an antibody (or serology) test, uses a blood sample to determine if you have developed antibodies against the COVID-19 virus. If antibodies are identified, it’s a sign you might have previously contracted COVID-19. 

Where Can I get a COVID-19 Test?

If you’re still not sure which COVID-19 test you need or where to get tested, call your health care provider or clinic for guidance. Testing is also available at walk-in clinics like UnityPoint Clinic – Urgent Care or UnityPoint Clinic – Express. If you start to feel very ill and need emergent medical attention, go to the emergency department or call 911. In the Emergency Department, you can be assessed for symptoms and be tested for COVID-19, if needed.

Why Are There So Many Coronavirus Test Types?

“There have always been different options for testing different respiratory viruses. We are now just more aware of what they are, since there is more testing occurring in our communities during this pandemic,” Dr. Rosa says.

What COVID-19 Test is Most Accurate?

Dr. Rosa says what test you use all depends on your situation.

“If a test is done because someone has symptoms of COVID-19, then it’s best to get a PCR test (molecular test), because it is the most sensitive. It will detect even the smallest fragments of the virus. If a person with symptoms gets a negative result with an antigen test, then it would need to be confirmed with a PCR test. On the other hand, if a test is done because someone was exposed, but doesn’t have symptoms, a less sensitive type of test could be used, whether molecular or antigen. However, in this last scenario it’s important to remember that even if you receive a negative test result you can still develop an infection later, so you still need to quarantine for 14 days,” Dr. Rosa says.

If you haven’t been exposed and don’t have symptoms, it’s referred to as testing for “contagiousness.” She says this strategy isn’t widely used or supported yet. It would only work if testing is done at frequent intervals. Testing to diagnose active disease as opposed to testing to detect contagiousness are two very different things.

How Long Does It Take to Get COVID-19 Test Results?

Usually antigen tests will give you results in less than an hour. Molecular tests take longer. For PCR, which is a common type of molecular test, results typically return in 24-48 hours. However, in times of high demand, results may be delayed up to seven days. Timing depends on how many tests the lab is handling and how quickly technicians can get to your sample. If you get a test at UnityPoint Health, you can sign up for a MyUnityPoint account to view your results as soon as they are available. 

What Happens to My COVID-19 Test Sample?

Antigen tests are put into relatively small machines or “cartridges.” It works similarly to a pregnancy test, which is why you get a rapid result.

“For PCR tests, the sample is taken to a central lab and prepared by technicians who put samples in a machine called a thermocycler. These machines multiply the genetic material several times, sort of like making copies on a copy machine, to determine if any virus is present.”

When Should I Get Tested for COVID-19?

If you have symptoms consistent with COVID-19, you’ve had a high-risk exposure (within six feet, for 15 minutes or more) to the virus and/or testing is advised by your health care provider or local/state department of public health.   

Symptoms of COVID-19, as identified by the CDC, include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Why Aren’t Asymptomatic Test Results Reliable?

“This is very important. If you have been exposed to COVID-19, you need to quarantine for 14 days even if you receive a negative test in the middle of your quarantine. This is because an infection can develop at any time during your 14-day self-quarantine,” Dr. Rosa says.

What Does My COVID-19 Test Result Mean?

Test results for antigen or molecular tests can come back in two ways:

  • Positive. You have been infected.
  • Negative. You are not currently infected.

However, Dr. Rosa says your test could be a false negative or a false positive. 

  • False negative. You are infected, but the test says you are not infected.
  • False positive. You are not infected, but the test says you are infected.

If you think you’ve received an inaccurate test result, discuss it with your doctor. For example, you get a negative test result, but you have symptoms consistent with COVID-19. Your health care provider might suggest taking a second test to confirm your results.

When Will COVID-19 Testing Change?

COVID-19 testing is rapidly changing. 

“There is some technology in development that would allow you to test for the virus at home using strips. But it’s not widely available yet. It’s important for everyone to stay up-to-date on the latest recommendations and advances to make the best use of the science and technology to reduce the spread of COVID-19.”