Hepatitis B Surface Antibody (HBsAb) Test

The hepatitis B surface antibody test (HBsAb) detects proteins called antibodies that are produced by the immune system in response to the hepatitis B virus (HBV). This test is used to determine if you are immune to the virus after natural exposure or vaccination.

This test should not be confused with the hepatitis B surface antigen (HBsAg) test or the hepatitis B core antibody (HBcAb) test, both of which are used to determine if you have HBV infection.

This article explains what hepatitis B surface antibodies are, when to use them, and how to test them. It also provides insights into what positive and negative test results mean.

What are Hepatitis B Surface Antibodies?

When you are exposed to HBV, your body builds an immune defense system to specifically target and neutralize the invader. Unlike innate immunity, which provides a comprehensive defense against all invaders, this type of immunity (called acquired immunity) is disease-specific.

This immune response occurs whether you have been exposed to HBV through blood or sexual contact, or have been vaccinated against hepatitis B.

The virus has proteins called antigens on its surface that act as unique identification tags. When HBV enters the body, the immune system “encodes” specific antibodies against these antigens in order to recognize and attack the virus when it reappears.

There are two types of antibodies that are produced in response to the virus:

  • Immunoglobulin M (IgM) is an antibody that initiates an initial attack but eventually disappears.
  • Immunoglobulin G (IgG) is an antibody that provides long-lasting immune protection against HBV. Immunity can last for many years but gradually weaken over time.


Hepatitis B surface antibodies are specific for the hepatitis B virus. The immune system produces two types: short-acting antibodies (IgM) that initiate an initial attack, and long-acting antibodies (IgG) that provide sustained immunity.

Testing purposes

The HBsAb test determines the presence and amount of HBV antibodies in your blood to determine how immune you are to the virus.

It can be used to find out if you have been exposed to HBV before (and indicate how close it is). Health care practitioners can also use this test to monitor your recovery from acute HBV infection by comparing levels of IgM and IgG.

Additionally, the HBsAb test can reveal whether the hepatitis B vaccination was successful and help determine if you need a booster vaccine (given that HBV antibodies drop below protective levels over time).


The HBsAb test detects the presence and quantity of HBV antibodies in the blood. It is used to determine your level of immunity to the virus.

How the test is done

The HBsAb test is done by taking a blood sample and sending it to a laboratory for analysis. Your healthcare provider will evaluate the results based on your vaccination history, symptoms and exposure risk, and the results of other hepatitis tests.

Interpret the results

Your HBsAb test result may be positive or negative, but the interpretation may vary depending on your HBsAg and HBcAb test results.


When the HBsAb result is positive (meaning the presence of surface antibodies), it usually means that you have recovered from a recent or previous hepatitis B infection and are immune to the virus. If both HBsAb and HBcAb are positive, a person is said to be immune due to natural infection.

If you have been vaccinated against hepatitis B, a positive HBsAb result itself indicates immunity.


If you test negative for HBsAb, it can mean many different things.Generally, this means that you are no immune to viruses.

Even so, there are different ways to interpret the results, depending on how they relate to other HBV tests.

test result explain
IgM positive
IgG negative
Acute (recent) infection
chronic (persistent) infection
Three possibilities:
1. Resolve the infection
2. False positives
3. Low-level chronic infection


A positive HBsAb result indicates that you are immune to HBV through natural infection or vaccination. Interpretation of negative results may vary with other HBV test results.

Interpreting the Hepatitis B Test

follow up

If you are HBsAb positive, you cannot infect others and do not need to be vaccinated.

If all three tests are negative – meaning you have never been exposed to the virus – you will be advised to get the HBV vaccine.

If your HBsAb test is negative, but other tests are positive, your healthcare provider will need to further evaluate you. Whether your infection is acute or chronic, you still have the ability to infect others and will be informed about ways to avoid it.

If the results are unclear, all three tests will be repeated.


The Hepatitis B Surface Antibody (HBsAb) test detects and measures the antibodies that the immune system makes against the hepatitis B virus. It is one of several tests used to diagnose hepatitis and is designed specifically to determine your level of immunity to the virus.

The test involves a simple blood draw that will return a positive or negative result. A positive result usually means you are immune to the virus and cannot infect others. Depending on the results of other tests, a negative result could mean any number of things.

VigorTip words

If all of your hepatitis tests are negative, you have not been exposed to the virus and are not immune. If this is the case, talk to your healthcare provider about getting vaccinated, regardless of whether you are at risk for hepatitis B.

Even if you are immune to hepatitis B, you may still be at risk for other types of hepatitis, including hepatitis C.

How to prevent viral hepatitis

Frequently Asked Questions

  • Can you beat hepatitis B?

    Yes. Most people fully recover from acute hepatitis B (hep B) infection. For mild symptoms, the best way to overcome an infection is to rest, drink fluids, eat well, and avoid alcohol, smoking, and drugs. About 5% of adults with acute hepatitis B develop chronic hepatitis B, which is incurable but manageable.

    understand more:

    living with hepatitis

  • What causes a positive hepatitis B surface antibody test?

    Having immunity to hepatitis B can result in a positive hepatitis B surface antibody test. This means that you have recovered from an infection or have been successfully vaccinated.

    understand more:

    Interpreting the results of a hepatitis B blood test

  • When should you be tested for hepatitis B antibodies?

    A hepatitis B surface antibody test is recommended to check hepatitis B immunity:

    • Babies whose mothers may have hepatitis B
    • Professionals who may be exposed to blood and body fluids
    • people on kidney dialysis
    • immunocompromised person
    • people with a hepatitis B positive partner

    understand more:

    Risk factors for hepatitis

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6 sources

VigorTip Health uses only high-quality resources, including peer-reviewed research, to support the facts in our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable and trustworthy.

  1. Song Zhe, Jindi. Diagnosis of Hepatitis B. Ann Translation Medicine2016;4(18):338. doi: 10.21037/atm.2016.09.11

  2. Hepatitis B Foundation. Vaccination.

  3. Centers for Disease Control and Prevention. Interpretation of hepatitis B serological test results.

  4. Centers for Disease Control and Prevention. Hepatitis B Q&A for Health Professionals.

  5. Hepatitis B Foundation. Hepatitis B blood test.

  6. Immunization Action Coalition. Hepatitis B.

Additional reading

  • Kasper, Dennis L.., Anthony S. Fauci and Stephen L.. Hauser. Harrison’s Principles of Internal Medicine. New York: McGraw-Hill Education. Print.

  • Kumar, Vinay, Abul K. Abbas and Jon C. Aster. Robbins and Cortland. Pathological basis of the disease. Philadelphia: Elsevier-Saunders. Print.

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