The novel coronavirus (COVID-19) pandemic has been confusing at times due to the ever-changing data reported daily. Adding to the confusion are three different types of tests that can be administered, but according to Memorial Medical Center (MMC), people are confused about which test to take.
On Friday, July 3, MMC posted on its Facebook, the three tests being used, but only two of them can determine a positive or negative result for an active infection.
The two tests that can determine a positive or negative result for an active infection are a PCR test or an Antigen test, more commonly known as a nasal or throat swab tests.
According to the Texas Department of State Health Services (DSHS), a PCR test looks for pieces of SARS-CoV-2, the virus that causes COVID-19, in the nose, throat, or other areas in the respiratory tract to determine if the person has an active infection, while the antigen tests look for proteins that make up the SARS- CoV-2 virus to determine if the person has an active infection.
In most cases, for both the PCR and Antigen tests, a nasal or throat swab is taken by a healthcare provider and tested.
“Sometimes, the test can be run while you wait, and sometimes the swab needs to be sent to a lab for testing,” DSHS website states.
If someone tests positive with a PCR or Antigen test, that means the person being tested has an active COVID-19 infection. A negative result in a PCR test means the person is probably not infected at the time their sample was taken
When someone tests positive using the PCR test, the health department will conduct a case investigation. Contact tracing will be performed to identify individuals who might have been exposed to the PCR- positive person when they could have spread COVID-19, according to the website.
If positive with the Antigen test, the health department will interview the antigen-positive person about symptoms and if they were around someone who had COVID-19. Contact tracing will be performed.
An Antigen test with a negative result means SARS-CoV-2 viral proteins were not detected.
“However, a negative test does not rule out COVID-19. If there is still concern that a person has COVID-19 after a negative antigen test, then that person should be tested again with a PCR test,” the website explains.
If someone tests negative in either the PCR or Antigen test, no public health activities will be performed.
The third test that is being performed is the Antibody (Serology) test, which uses a blood sample that is sent to a lab for testing. The Antibody test looks for antibodies against SARS-CoV-2 in the blood to determine if there was a past infection.
According to the state’s website, a positive antibody test means that the person being tested was infected with COVID-19 in the past and that their immune system developed antibodies to try to fight it off. On the other hand, if negative, the person may not have had COVID-19 in the past. However, they could still have a current infection, and the antibody test was collected too soon to give a positive result.
In addition, the state’s website says they do not know yet if having antibodies to the virus that causes COVID-19 can protect someone from getting infected again or, if they do, how long this protection might last.
“Until scientists get more information about whether antibodies protect against reinfection with this virus, everyone should continue to take steps to protect themselves and others, including staying at least 6 feet away from other people outside of their home (social distancing), even if they have had a positive antibody test,” the state said.
Before a person gets tested, they need to be aware of the test they need and get the correct test administered.
“Some labs in the area are offering “rapid COVID-19 blood testing”. Please be aware that blood testing is not used to diagnose an active COVID-19 infection, and advertising this sort of testing is misleading,” MMC’s Facebook says.