What are antibody serology tests?

Antibody serology tests check for the presence or level of specific antibodies in the blood. Antibodies are proteins that your immune system makes to fight foreign substances. These substances are often pathogens, (disease-causing germs) such as viruses and bacteria. When you have an infection, your body makes antibodies that are targeted to those pathogen. These antibodies may protect you from getting another infection or from getting severe symptoms. A vaccine can also provide protection by triggering your immune system to make antibodies to pathogen.

An antibody serology test can show that your immune system can fight off certain diseases.

Other names: antibody titer test, antibody test, antibody serum test

What are they used for?

Antibody serology tests are used to look for antibodies to specific diseases. These include:

• COVID-19
• Measles and mumps
• Varicella zoster virus, which includes chickenpox and shingles
• Hepatitis
• Mononucleosis

The tests may also be used to check for certain antibodies that may be a sign of an autoimmune disease. Autoimmune diseases cause your immune system to attack your own cells, tissues, and/or organs by mistake.

Antibody serology tests are not used to diagnose diseases. They can show that you have antibodies to a disease. But they can't show if the antibodies are from a current or past infection or from a vaccination.

Why do I need an antibody serology test?

You may need this test:

• To find out if you've had a recent or past infection.
• To check your vaccination status. If your medical records are incomplete, you may need this test to find out if you've been vaccinated.
• To find out if a vaccine is effective. If you've already been vaccinated against a disease, the test can show if your vaccine is providing enough protection.
• As a requirement for your school or job. Some organizations may require proof of past infection or vaccination.
• To find out if you have an autoimmune disease, such as lupus.

What happens during an antibody serology test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for this test?

You don't need any special preparations for an antibody serology test.

Are there any risks to this test?

There is very little risk to having a blood test. There may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

Your results will depend on which antibodies were measured. Results may be given as titers (levels of antibodies) or as positive (you have antibodies) or negative (you do not have antibodies).

Common results include:

• Antibodies to a specific pathogen were found. This may mean you had a previous infection. It could also mean you've been vaccinated against a certain disease.
• Low levels of certain antibodies were found. This may mean a previous vaccination is not providing you with enough protection against a disease. It also means you may need a booster shot.
• Autoantibodies were found. Autoantibodies are a type of antibody that attacks healthy cells by mistake. This may mean you have an autoimmune disease.

If you have questions about your results, talk to your health care provider.

Learn more about laboratory tests, references ranges, understanding results.

Is there anything else I need to know about an antibody serology test?

Antibody serology tests can show that you have an immune response to a pathogen. But they cannot show if you have full protection from a disease or how long the protection lasts. In the case of a newer disease like COVID-19, it is not yet known how long protection lasts after being infected or vaccinated.