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Key Takeaways
- A positive HBsAb blood test means you are immune to hepatitis B.
- A negative HBsAb test means you are not immune and may need a vaccine.
The hepatitis B surface antibody test (HBsAb) checks if you’re immune to the hepatitis B virus, indicating your protection level against the infection through vaccination or prior infection. A positive blood test result indicates immunity, while a negative result means you may not be protected from the virus.
Illustration by Julie Bang for Verywell Health
Why Get Tested for Hepatitis B Immunity?
The HBsAb test checks for the presence and amount of hepatitis B virus (HBV) antibodies in your blood. It indicates your level of immunity to the virus.
Your immune system creates antibodies when exposed to HBV through blood or sexual contact, or after getting the hepatitis B vaccine. These antibodies help your body combat the virus if it reappears.
Types of Antibodies in Response to HBV
There are two types of antibodies produced in response to the hepatitis B virus:
- Immunoglobulin M (IgM): The first antibody to attack the virus but eventually fades.
- Immunoglobulin G (IgG): Provides long-term immune protection that lasts for years, though it gradually decreases over time.
The HBsAb test can check for a previous exposure to HBV and tell how recent it was. By comparing levels of IgM and IgG, a healthcare provider can also use the test to monitor your recovery from an acute HBV infection.
The HBsAb test checks if your vaccine protection is adequate. It can show whether you are successfully vaccinated, not successfully vaccinated, or indeterminately vaccinated. You might need a booster if your HBsAb level drops below protective levels.
The HBsAb test is not the same as the hepatitis B surface antigen (HBsAg) test or the hepatitis B core antibody (HBcAb) test. Those tests are used to determine if you have been infected with HBV.
Who Should Get a Hepatitis B Antibody Test?
A hepatitis B surface antibody test is recommended for:
- Infants born to people who may have hepatitis B
- Workers with potential exposure to blood and body fluids
- People undergoing kidney dialysis
- Immunocompromised individuals
- Those with a hepatitis B-positive partner
How the HBsAb Test Is Done
The HBsAb test is done by taking a blood sample that can be sent to the lab. Your healthcare provider will check the results against your vaccination history, symptoms, and exposure risk, as well as the results of other hepatitis tests.
Understanding Your Test Results
Your HBsAb test can be positive or negative. Your healthcare provider will consider the results along with other tests, like HBsAg and HBcAb, to interpret your condition.
Positive
If your HBsAb result is positive or “reactive”—meaning the surface antibodies are present—it usually means that you have recovered from a recent or previous hepatitis B infection and that you are immune to the virus. If both the HBsAb and HBcAb are positive, you are said to be immune due to natural infection.
If you’ve had the hepatitis B vaccine, a positive HBsAb result alone confirms your immunity.
Negative
A negative or “non-reactive” HBsAb test generally means you are not immune to the virus.
The chart presents several ways to interpret HBsAb test results based on the results of the other hepatitis B tests.
| Test | Result | Interpretation |
| HBsAb HBsAg HBcAb |
Negative Negative Negative |
Not infected |
| HBsAb HBsAg HBcAb |
IgM Positive IgG Negative Negative |
Acute (recent) infection |
| HBsAb HBsAg HBcAb |
Negative Positive Positive |
Chronic (ongoing) infection |
| HBsAb HBsAg HBcAb |
Negative Negative Positive |
Three possibilities: 1. Resolved infection 2. False positive 3. Low-level chronic infection |
Next Steps After Your Hepatitis B Test
If your HBsAb is positive, you cannot infect others and do not need vaccination.
If all three tests are negative—meaning that you have never been exposed to the virus—you will be advised to get the HBV vaccine.
If your HBsAb test is negative but the other tests are positive, your healthcare provider will need to evaluate you further. Whether your infection is acute or chronic, you still have the ability to infect others and need to take steps to avoid spreading the virus.
If the results are unclear, all three tests will be repeated.
Treatment Options for Hepatitis B
If your hepatitis B surface antibody test is positive, your provider will review your other blood tests to decide if you need treatment.
Medications for hepatitis B may include:
- Immune modulators: hese help your immune system eliminate hepatitis B. They are usually given as shots for six months to a year.
- Antivirals: These oral medications assist your body in clearing the hepatitis virus. They typically require daily use for at least a year or longer.