Antibody Titer Test

About the Test

Purpose of the test

The purpose of this test is to check the levels of certain antibodies in the blood. These levels are known as antibody titers. When titers are above a certain threshold, it demonstrates that the immune system has had prior exposure to either a vaccine or pathogen.

An antibody titer test can be used in several different situations:

• Assessing past disease exposure: The presence of antibodies can reflect previous exposure to a pathogen.
• Determining vaccination history In people who do not have complete or reliable medical records, an antibody titer test may identify the vaccines that they have already received. Most often, this occurs with children or adults immigrating to the United States without detailed medical records. In this context, it may be referred to as an immunization test.
• Meeting requirements for schools, employers, or assisted-living facilities: Proof of vaccination is required in various contexts, and when medical records cannot provide this proof, an antibody titer test may be an option to prove that you have received a certain vaccine.
• Assessing past disease exposure: The presence of antibodies can reflect previous exposure to a pathogen.
• Evaluating immune function: People with some immune diseases do not properly develop antibodies after pathogen exposure or vaccine administration. This can cause recurring infections or leave them susceptible to vaccine-preventable illnesses. A titer test may be used after vaccination to see if their immune system responds properly.
• Diagnosing autoimmune diseases: In some conditions, the immune system attacks the body’s own cells. The presence of certain types of antibodies can be an indication of an autoimmune problem.
• Protecting healthcare workers: Medical workers may need a titer test to ensure that they have antibodies to viruses to which they have frequent exposure.

What does the test measure?

The test measures antibody titers. This is a technical term for levels of a type of protein produced by the immune system. Specific antibodies are produced in response to specific pathogens like viruses.

The presence of a certain amount of antibodies can demonstrate that a person has been vaccinated or has been exposed to a particular pathogen. A few examples of antibodies in the blood that may be measured to learn about immunization or past infection include:

• Measles and mumps
• Rubella
• Varicella zoster virus, which causes chickenpox and shingles
• Hepatitis A, Hepatitis B
• Tetanus and diphtheria
• COVID-19

Blood can be analyzed to measure dozens of other specific antibodies associated with a broad range of medical conditions. Several different test methods are available depending on the kind of antibodies being measured.

When measuring antibody titers related to immunization, it is important to remember that the presence of antibodies does not guarantee protection. There is no test to definitively prove complete immunity to a pathogen. Also, the absence of specific antibodies does not mean that the body could not mount an immune response against that specific disease. This is because there are other segments of the immune system responsible for fighting pathogens.

When should I get immunization testing?

Antibody titer testing to evaluate immune function or identify active or past infections are tailored to your specific circumstances. Your doctor is in the best position to review the potential benefits and downsides of testing in your situation. Talk with a doctor to determine whether antibody testing is right for you.

In some cases, antibody titer testing may be used to inform a schedule for vaccines. However, when vaccination status is unclear, doctors may recommend age-appropriate vaccinations without doing immunization testing.