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What you should know about coronavirus antibody tests

CORONAVIRUS UPDATE: As experts learn more about the novel coronavirus, news and information changes. For the latest on the COVID-19 pandemic, please visit the Centers for Disease Control and Prevention.

What is a coronavirus antibody test? | Who should be tested | How to get a test | Test results

When it comes to the novel coronavirus (COVID-19), most people have one primary concern. Have I been exposed? There are currently two ways to determine if you caught the virus: diagnostic testing and antibody testing. A diagnostic test tells you if you currently have the infection. Antibody testing reveals if you were previously exposed and developed antibodies. Continue reading to find out everything you need to know about COVID-19 antibody testing. 

What is a coronavirus antibody test?

A diagnostic test determines if you currently have COVID-19. The sample is obtained using a nasal swab or saliva sample. The coronavirus test looks for active viral infection with SARS-CoV-2, the virus that causes COVID-19. 

A coronavirus antibody test (also called serology testing) can tell you if you have been exposed to COVID-19. It looks for different types of antibodies that your immune system makes when it encounters the virus. Some antibody tests look for IgG antibodies; others look for both IgG and IgM antibodies. 

IgM antibodies: When IgM antibodies are present, they can indicate an active or recent infection. 

IgG antibodies: IgG antibodies develop later, about seven to 21 days after infection. The presence of IgG antibodies in your lab work can indicate a past infection. 

It’s important to note that a positive antibody test doesn’t mean that you can’t spread the virus to others, or catch it again

You may still be contagious, especially if IgM antibodies are also present. Having the antibodies does not necessarily mean that you are immune to infection. It’s unknown how long the antibodies last in your system, and scientists are still studying this. 

Why is the antibody test important? 

  • If the test shows that you have IgG antibodies, you may have some immunity. It indicates that you were likely infected with or exposed to COVID-19. However,  infectious disease experts don’t know yet if having antibodies means that you are protected against reinfection with COVID-19 in the future. Researchers are still studying this. 
  • If you have recovered from COVID-19, you may be eligible to donate plasma, which can treat patients who are very ill and help them fight the infection. This plasma is called convalescent plasma and it is being studied in trials. You can find out more about donating plasma here
  • Results of antibody testing will provide public health officials and researchers with more information about the prevalence of COVID-19, immunity, community spread, and other factors. 

Who should be tested for the coronavirus? 

You should get a COVID-19 antibody test if:

  • You think you have been exposed to COVID-19.
  • You have been diagnosed with COVID-19 and are fully recovered.
  • You previously had symptoms of COVID-19 but were not tested (perhaps due to lack of widespread testing at the time).

If you currently have coronavirus symptoms, you should contact your healthcare provider about a diagnostic test, not an antibody test. An antibody test will not tell you if you currently have COVID-19. 

How to get a COVID-19 antibody test

According to the CDC, antibody tests are currently available through healthcare providers and laboratories. Contact your healthcare provider to see if testing is offered. You can also go online at Quest Diagnostics or LabCorp and follow the steps to have a doctor order an antibody test, which you will take at a participating lab. 

The antibody test is a simple blood test. The blood sample will then be tested for the presence of antibodies. 

Currently, there are no antibody tests that use a home collection. Scanwell Health and Lemonaid Health are developing an at-home antibody test that might soon be available. 

RELATED: Compare COVID-19 at-home test kits

Can I trust the COVID-19 antibody test results?

There is a lot of talk about false test results and the accuracy of the antibody test results. 

False positives

If you have been diagnosed with or were exposed to another type of coronavirus, you may get a false-positive result. Or, if you test too soon after recovering from the virus, you may not have enough IgG antibodies to be detected and get a false negative result. 

Accuracy

It’s important to note that the COVID-19 testing kits currently available have been authorized under the U.S. Food and Drug Administration’s (FDA) EUA, or emergency use authorization program. The EUA allows unapproved medical products (or unapproved uses of already approved medical products) to be used in an emergency for the diagnosis, treatment, or prevention of life-threatening diseases or conditions when there are no adequate, accepted, and available alternatives. 

However, that doesn’t mean that the companies aren’t being held accountable. The FDA is taking steps to ensure that more testing is available and that the coronavirus and antibodies tests are accurate, by collecting validation data and ensuring tests meet specific recommendations for specificity and sensitivity. 

What do my antibody test results mean? 

The CDC outlines actionable steps for people who receive either a positive or negative test results here. No matter what your results show, you should still follow these measures, such as frequent handwashing, wearing a mask, and avoiding close contact, to protect yourself and others. 

A positive test result doesn’t necessarily mean that you’re immune to COVID-19, or that you can go back to work. You may need a negative diagnostic test for an active COVID-19 infection first.

If you aren’t experiencing any symptoms, ask your healthcare provider if it is okay to go back to work, taking all the appropriate precautions (wearing a mask, social distancing, etc.). 

If you are currently having symptoms, a negative antibody result may be from a current COVID-19 infection, and you will need a follow-up test. Your healthcare provider will guide you to the appropriate steps to take.