Understanding Antibody Testing

Can you become immune once you have COVID-19? According to the Centers for Disease Control and Prevention (CDC), there is currently not enough information to determine if people who recover from COVID-19 can be infected again, or if antibodies prevent it. The answers below can help you gain a better understanding of antibodies and antibody testing related to COVID-19.

What are antibodies?
Antibodies are proteins produced by the body's immune system in response to an infection or disease. Since antibodies are specific to a disease or virus, they can help fight off current infections and prevent against the disease in the future.

What is an antibody test?
An antibody test, also known as a serology test, is a blood test that helps determine if you have already had a virus or disease such as COVID-19. While the test cannot detect if you are currently infected, it can detect the presence of antibodies. According to the CDC, antibody testing may help support a diagnosis of COVID-19 in people who continue to experience symptoms many days or weeks after the symptoms started. This is because COVID-19 antibodies will start to form whether or not the person has recovered. Until scientists are able to gather additional data on whether antibodies protect against reinfection of COVID-19, the CDC does not recommend using antibody testing to determine immunity.

Where do I go for an antibody test?
Antibody testing is not recommended for most people. You can ask your doctor or health care professional whether you should be tested and where to go for antibody testing. You can also visit your state or local health department websites to see if antibody testing is available near you.

Is a nasal swab used to administer the antibody test?
No, a health care professional will draw blood from a vein in your arm or prick your finger. The blood sample is then tested in a lab to detect antibodies.

What do my antibody test results mean?
You should talk with your doctor or health care professional about what your test results mean for you.

Keep in mind that you may test negative for COVID-19 antibodies if:

• You have never had it.
• You still have COVID-19, and your body has not developed antibodies yet. It takes one to three weeks after infection for your body to make antibodies. In some it may take even longer.
• You were infected, but never developed antibodies.
• The test gives you an incorrect result.

Your test may also come back positive for COVID-19 antibodies if:

• The virus you had is in the same coronavirus family, but not from the same virus that causes COVID-19.
• You had the virus, but never showed symptoms of COVID-19.
• The test gives you an incorrect result.

If my antibody test is positive, would donating my blood plasma help others?
Researchers are studying how COVID-19 antibodies in blood plasma may help boost a person's ability to fight off the virus or help those with serious complications. There are programs focused on increasing blood plasma donations from people who have had COVID-19.

For example, The Fight Is In Us is a public-private coalition working to find new treatments for patients with COVID-19 using blood plasma. This organization encourages COVID-19 survivors to donate within two months of their recovery to help ensure that their blood plasma contains enough antibodies to make a positive impact. Visit their website to find a donation location close to you.

We all play a part in helping to stop the spread of COVID-19. Staying informed can help you keep yourself and others safe and healthy.