A serology test is a blood test that detects antibodies or antigens in your blood to determine whether you have been exposed to a specific infection or have developed immunity against it. Unlike tests that look for the pathogen itself (such as PCR swabs), serology tests measure your immune system's response to an infection or vaccination.

When your body encounters a virus or bacterium, your immune system produces different types of protective proteins known as antibodies.

By identifying which antibodies are present, a serology test can reveal whether an infection is recent, past, or whether you are immune. This makes serology testing useful for a wide range of purposes, from diagnosing active infections to confirming immunity before vaccination.

A serology test works by analysing a blood sample for specific antibodies or antigens produced in response to infections. A small blood sample is drawn, typically from a vein in your arm, and sent to a laboratory for analysis.

The laboratory uses techniques such as enzyme-linked immunosorbent assay (ELISA) or chemiluminescent immunoassay (CLIA) to detect and measure antibody levels. The two most commonly tested antibody types are:

• IgM antibodies are the first antibodies your immune system produces when it encounters a new infection, usually within the first one to two weeks. Their presence typically indicates a recent or active infection.
• IgG antibodies are produced later and often remain in the bloodstream long-term. Their presence usually indicates a past infection or successful vaccination, meaning you have likely developed immunity.

Some serology tests also detect antigens, which are proteins from the pathogen itself rather than antibodies from your immune system. Hepatitis B surface antigen (HBsAg) testing is a common example.

Serology tests cover a broad range of infections and conditions. They can be grouped by their purpose: immunity testing, infection screening, and autoimmune detection.

Immunity and Vaccination Serology Tests

Infection Screening Serology Tests

These tests detect whether you currently have or have previously been infected with a specific pathogen. They are commonly used in STD screening, antenatal care, and general health assessments.

Examples include:

• HIV antigen (Ag) / antibody (Ab) screens for HIV infection by detecting both antigens and antibodies
• Syphilis TP antibody screens for syphilis infection
• Hepatitis B surface antigen (HBsAg) detects active hepatitis B infection
• Herpes Simplex IgG (Type 1 and Type 2) identifies past exposure to herpes simplex virus
• Dengue IgG and IgM help diagnose current or recent dengue infection
• Cytomegalovirus (CMV) IgG and IgM detect past or recent CMV infection

Autoimmune Serology Tests

Autoimmune serology tests detect antibodies that mistakenly target the body's own tissues, which can indicate autoimmune conditions.

Examples include:

• Anti-Nuclear Antibody (ANA) screens for autoimmune conditions such as lupus
• Anti-ds DNA helps confirm a diagnosis of systemic lupus erythematosus (SLE)
• Rheumatoid Factor (RF) supports the evaluation of rheumatoid arthritis

Premarital and Pregnancy Screening

Serology tests form a key part of premarital screening and antenatal care. Tests for rubella immunity, hepatitis B, HIV, and syphilis are routinely included in pregnancy blood panels to help identify risks to both mother and child early.

STD Screening

Blood-based serology tests are a commonly used method for screening infections such as HIV, syphilis, hepatitis B, hepatitis C, and herpes simplex. These can be done as individual tests or as part of a comprehensive STD screening panel.

Confirming Immunity Before Vaccination

If you are unsure whether you have been vaccinated or had a particular disease, a serology test can check your antibody levels before deciding on vaccination. This avoids unnecessary doses and confirms whether boosters are needed.

Diagnosing Active or Past Infections

When symptoms suggest a possible infection, serology tests can help identify the cause. For example, dengue serology can indicate whether an infection is current or past based on the type of antibodies detected, though results may require clinical interpretation in some cases.

No, you do not need to fast before a serology test. Unlike cholesterol or blood glucose tests, serology tests measure antibodies and antigens that are not affected by food intake. You can eat and drink normally before your appointment.

The blood draw itself takes only a few minutes. Results are typically available within a few working days, depending on the specific test.

Serology test results are typically reported as reactive (positive) or non-reactive (negative), and some tests also include antibody levels (titres).

Some tests report numerical antibody levels (titres) rather than a simple positive or negative. Higher titres generally suggest stronger immunity, though for infection screening tests, titres may reflect disease activity rather than protection.

Your doctor will interpret your results based on the specific test and the antibody levels required for protection or diagnosis.

At ATA Medical, we offer a comprehensive range of serology tests. The following prices apply:

*Prices are NETT and inclusive of GST.
^Prices last updated on Apr 02, 2026. While every effort is made to keep pricing information up to date, please contact our team to confirm the latest rates.

For a full list of available tests, visit our blood test page.

If you are looking for STD-related serology, our STD test page includes bundled screening packages. You may also wish to consult our women's health doctor or men's health doctor if you have specific concerns.

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