East Texas public health expert, infectious disease specialist explain differences between COVID-19 tests

Types of Covid Tests

TYLER, Texas (KLTV) - East Texas school districts, employers, and even sports teams are developing testing policies for exposure to COVID-19 or those who exhibit symptoms of the virus. In some situations, testing can be a requirement for travel or in nursing homes.

Understanding the differences between the three available tests is an important step in responding to COVID-19, according to the Northeast Texas Public Health District (NET Health).

Polymerase Chain Reaction (PCR)

“That’s the one with the highest degree of accuracy in determining if someone has the virus,” said Dr. Ed Dominguez, KLTV 7 Med Team Doctor and infectious disease specialist.

PCR tests detects whether someone is currently infected with COVID-19 by identifying the virus through DNA. A sample is typically collected through a nasal or throat swab, then tested.

“The gold standard for being infectious, a danger to others, is the PCR,” said Russell Hopkins, director of Public Health Emergency Preparedness at NET Health.

Antigen

With antigen tests, a swab is also taken in the nose or throat, but this type looks for certain proteins to detect an active infection. Also, a negative test result doesn’t rule out COVID-19. According to the Texas Department of Health and Human Services, antigen tests are less sensitive than PCR tests, so there may be false negatives.

“That test is a good test, but it’s not a great test. And if it’s positive or if it’s negative, in the right setting, then it still has to be backed up with the nasal (PCR) test,” Dr. Dominguez.

Antibody (Serology)

The third type of test looks for antibodies, usually through a blood sample. It only looks for infection in the past, even if no symptoms were displayed.

“The tell us if somebody has been exposed, but it doesn’t tell us when they were exposed. Nor does it tell us if they are actively infected right now,” said Dr. Dominguez.

The Department of State Health Services reports it’s possible for someone with an active COVID-19 infection to test negative for antibodies if it’s used too close to the beginning of an infection.

Hopkins says each test can provide valuable information for individuals, organizations, the medical community, and public health professionals.

“Are you looking to go back to work, are you looking to change your behavior, cancel a trip? Those kinds of things will then come into play in what kinds of tests you should seek out.”

Click here for a detailed comparison of each test.

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