Covid-19 Antibody Testing

Is COVID-19 antibody testing useful?

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COVID-19 vaccinations are underway, a crucial step in the evolving effort to curb the spread and lethality of the global pandemic.

SIU Medicine wants our patients and the public to have confidence in the process. We encourage questions about your concerns and how to best protect against the virus. Sharing information will help the community stay safer and better informed.

One question frequently heard is: Can I get an antibody test if I have had the vaccine?

Understanding antibodies

Antibodies are proteins produced by immune cells that circulate in your body. They help fight off infectious diseases and may prevent you from becoming ill or make the illness very minor by boosting your body’s defenses.

Your immune system can create antibodies following exposure to almost anything considered “foreign.” In the context of this pandemic, this would include:

  • Actual infection from the virus that causes COVID-19 or
  • Receiving one of the COVID-19 vaccines that trains your immune system to recognize pieces of that foreign virus

Antibodies act like "tags" that help your immune system quickly recognize, neutralize and recruit other immune cells to elicit protection.

With some small differences, antibodies that are developed after vaccination are often the same as antibodies that develop after getting infected. The variety of antibodies produced can vary depending on whether they were produced naturally or from a vaccine. The length of time antibodies can provide protection (immunity) can differ depending on several factors, including the specific disease, the individual person and if there is repeated exposure.

Since COVID-19 is new, we don't fully understand how long the COVID-19 antibodies remain in our bodies to provide protection. However, based on the best-available evidence, experts agree that getting vaccinated against COVID-19  is one of the best ways to prevent the spread of the disease and keep yourself, your family and your community safer.

COVID-19 antibody tests after the vaccine: what you need to know

A COVID-19 antibody test is a blood test that can detect whether your blood contains antibodies that protect against SARS-CoV-2, the virus that causes COVID-19. If you have previously been infected with COVID-19 or if you received a COVID-19 vaccine and then receive an antibody test, it's likely that you'd get a positive result on a COVID-19 antibody test. There are a lot of different antibody tests on the market that vary in sensitivity and which type of antibody is being tested.

Keep in mind that SARS-CoV-2 comes from a large family of viruses called coronavirus, and many other types of coronaviruses exist. For this reason, it is critical that an appropriate SARS-CoV-2-specific antibody test is used. Selection of the appropriate antibody test should be discussed with your physician.

A positive COVID-19 antibody test does not necessarily mean you can’t become infected with the virus that causes COVID-19 later on. While extremely rare, cases have been reported of people testing positive for COVID-19 virus after they already had recovered from COVID-19 or after they have been vaccinated for it. In addition, a positive COVID-19 antibody test does not mean you cannot spread the virus to others. 

Overall, an antibody test after vaccination for COVID-19 is not required, and a positive antibody test will not necessarily prove you are completely immune to COVID-19. These help explain why experts still recommend continuing preventive measures like masks, hand washing and social distancing even after you get the COVID-19 vaccine.

If you're wondering whether you need a COVID-19 antibody test, check with your health care provider. You can also contact SIU Medicine at 217-545-8000 to stay up-to-date on COVID-related news, including our current testing locations for the month of February.

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