Types of COVID-19 Testing

Published on by Shanthy (SGR)

There comes a point when the thought crosses our mind whether we are immune or have we already been impacted by the virus and never realized it as we were home-borne.

How do we know whether we have been impacted and never realized, or are we immune? If we have recovered without our knowledge, can we donate plasma to others? CDC and FDA seems to have provided answers to some of these questions recently.

Broadly, there are 3 types of tests

Molecular tests – Detect genetic material from the virus. A nasal / throat swab collect infected cells. Tests tell us whether we are infected now.

Antigen tests – Detect antigens – pieces of the virus that the immune system recognizes. A nasal swab collects infected cells. Tests tell us whether we are infected now.

Antibody tests – Detect antibodies made by the immune response to fight the virus and disable/mark it for destruction. Blood draw collects antibodies produced by immune cells. Tests measure whether these antibodies bind to the virus. Tests tell us whether we have been infected in the past.

Quest launched IgG antibody serology testing by blood draw to help patients and healthcare professionals identify who may have recovered from a prior infection and may possibly have a lower risk of reinfection.

– Tests being run since April 2020

So, what is Plasma donation? Convalescent plasma is the liquid part of blood that is collected from patients who have recovered from the novel coronavirus disease, COVID-19, caused by the virus SARS-CoV-2. COVID-19 patients develop antibodies in the blood against the virus. Antibodies are proteins that might help fight the infection. Convalescent plasma is being investigated for the treatment of COVID-19 because there is no approved treatment for this disease and there is some information that suggests it might help some patients recover from COVID-19.

So, if you have recovered – can you donate Plasma to others?

FDA quotes – People who have fully recovered from COVID-19 for at least two weeks are encouraged to consider donating plasma, which may help save the lives of other patients. COVID-19 convalescent plasma must only be collected from recovered individuals if they are eligible to donate blood. Individuals must have had a prior diagnosis of COVID-19 documented by a laboratory test and meet other donor criteria. Individuals must have complete resolution of symptoms for at least 14 days prior to donation. A negative lab test for active COVID-19 disease is not necessary to qualify for donation. 

If you feel you have had COVID-19 symptoms and have recovered, you can discuss with your physician to see if you can have your antibody testing done (as part of your blood panel), or have a testing done at Quest or Labcorp. Based on the outcome of your discussion, you choose to donate plasma. Talk to your local hospital / Red cross on your nearby blood/plasma donation locations (you can google search for plasma donation location near me).

If your antibody test turns out to be positive

  • A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance a positive result means that you have antibodies from an infection with a virus from the same family of viruses (called coronaviruses), such as the one that causes the common cold.
  • Having antibodies to the virus that causes COVID-19 may provide protection from getting infected with the virus again.
  • Talk with your physician about your test result and the type of test you took to understand what your result means.
  • You may be prone to getting infected again – so, check with your physician on how to protect yourself
    • If you work in a job where you wear personal protective equipment (PPE), continue wearing PPE.
  • You may test positive for antibodies even if you have never had symptoms of COVID-19. This can happen if you had an infection without symptoms, which is called an asymptomatic infection.

If your antibody test turns out to be negative

  • You may not have ever had COVID-19.
  • You could still have a current infection.
    • The test may be negative because it typically takes 1–3 weeks after infection for your body to make antibodies. It’s possible you could still get sick if you have been exposed to the virus recently. This means you could still spread the virus.
    • Some people may take even longer to develop antibodies, and some people who are infected may not ever develop antibodies.
  • If you get symptoms after the antibody test, you might need another test called a viral test​.

For more information refer sources below:

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