What Is Immunity?

Immunity is when antibodies — proteins your body generates — are present that can help the body resist harmful microorganisms or toxins. Antibodies are disease-specific and there is no broad-based “immunity” that protects the body. Immunity can be active or passive. When you are exposed to an infectious agent (such as a virus or bacteria) that triggers the body to produce antibodies, you may develop active immunity, which you can achieve naturally or by getting vaccinated.

Either way, if your body is exposed to a disease-causing agent and your immune system recognizes it, then it may respond by producing antibodies to fight it. Passive immunity is when you are given antibodies to a disease rather than your body producing disease-fighting proteins. Active immunity can take time to develop while passive immunity is immediate but not as long-lasting.

The Role of Immunity Testing

You can test for the presence or level of an antibody in blood using a serology test. The test can show whether your body could protect you from getting an infection or from getting severe disease symptoms.

Who should get an immunity test?

Antibody testing can identify antibodies for a specific disease-causing agent. You can also get antibody testing to identify a potential autoimmune disease.

To find out if you’ve had a recent or past infection, you may need an antibody test – especially if you may have been infected but are asymptomatic and want to protect others’ health. Antibody tests can identify your vaccination status or may determine whether a vaccination is effective and your body has enough protection. Some employers or organizations require an antibody titer test as proof of vaccination.

More Immunity Tests

Getting Tested for Immunity

Serology tests show whether the body has antibodies present for a specific disease. These tests do not indicate whether the antibodies are from a past or current infection, or vaccination. Immunity testing is not used for diagnosis. Antibody tests can show a level or titer, or they can indicate reactive or non-reactive negative for specific antibodies.

Cost of immunity testing

The cost of an immunity (serology antibody) test will vary by location and test type. Some clinics, usually community or nonprofit clinics, offer free or low-cost testing. Labs, clinics, and at-home testing companies may accept insurance to cover or lower your cost of testing.

Types of sample collection

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.

Getting immunity test results

Usually, you will receive test results within a few business days of providing a blood sample to the lab. It is always a good idea to review results with your doctor, who might suggest further evaluation, testing, or vaccination to protect your immunity.

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 or you’ve been vaccinated against a certain disease.
  • Low levels of certain antibodies were found – this may indicate that 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 – these are a type of antibody that attacks healthy cells by mistake, and may reveal you have an autoimmune disease.


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