An antibody test, also known as a serology test, detects antibodies in your blood. These antibodies are proteins your immune system produces to fight off infections. The test reveals if your body has encountered a specific disease, like measles, mumps, chickenpox, shingles, hepatitis, or HIV, or has developed immunity to it. It can also be used to identify if someone has recovered from an infection, such as COVID-19.
How Antibody Tests Work
Antibody tests work by analyzing a blood sample (or sometimes oral fluid) for the presence of specific antibodies. If antibodies are present, it suggests past exposure to the disease. The absence of antibodies does not always guarantee the absence of infection, especially in the early stages.
Types of Antibodies Detected:
Several types of antibodies exist, including IgG, IgM, and IgA. These antibody types appear and disappear at different points during and after an infection, providing insights into the stage of infection.
- IgG: Generally appears later in the infection and indicates a longer-term immune response or prior exposure.
- IgM: Usually shows up early during an infection.
- IgA: Found mainly in mucous membranes.
Uses of Antibody Tests:
Antibody tests are used for various purposes:
- Diagnosing infections: Detecting current or past exposure to a specific disease.
- Monitoring disease progression: Tracking the body's immune response over time.
- Assessing immunity: Determining if an individual is immune to certain diseases, such as after vaccination.
- Identifying autoimmune diseases: Detecting antibodies targeting the body's own tissues. For example, thyroid antibody tests look for antibodies affecting the thyroid gland.
- Confirming recovery from disease: Determining if someone has recovered from an infection like COVID-19.
Accuracy of Antibody Tests:
The accuracy of an antibody test depends on its sensitivity (how well it identifies those with the disease) and its specificity (how well it avoids identifying those without the disease).
Examples of Antibody Tests:
- COVID-19 antibody test: Detects antibodies against the SARS-CoV-2 virus.
- Hepatitis C antibody test: Detects antibodies to the hepatitis C virus.
- HIV antibody test: Detects antibodies to the HIV virus.
- Measles, mumps, and rubella (MMR) antibody test: Checks for antibodies to measles, mumps, and rubella viruses.
- Thyroid antibody tests: Detects antibodies that target the thyroid gland.
