Hepatitis B surface antibody (anti-HBs)

Hepatitis B surface antibody (anti-HBs)

November 27, 2020

Hepatitis B Immunity

What is Hepatitis B surface antibody?

Hepatitis B surface antibodies (anti-HBs) are produced by our immune system in response to the hepatitis B surface antigen – the protein on the surface of the hepatitis B virus which indicates infection. The presence of these antibodies provide us with immunity against hepatitis B infection. Measurement of anti-HBs can identify previous hepatitis B infection or successful vaccination against hepatitis B. The test is usually performed between 1 to 4 months (preferably 3 months) after the completion of a course (3 shots) of the Hepatitis B vaccine.

Why is this analysis important?

Hepatitis B is an infectious disease caused by the hepatitis B virus that can lead to an acute or chronic liver infection that can severely damage the liver. It is transmitted by contact with infected blood or bodily fluids. Vaccination against hepatitis B is recommended for adults and children that are at high risk of infection which may be due to occupational exposure, or travel to certain areas of the world.


The anti-HBs test is a quantitative assay that measures anti-HBs levels between 3.1–1000.0 mIU/mL with high sensitivity and specificity. The clinical sensitivity for vaccinated or naturally infected individuals is 99.5% (95% confidence interval 97.45%–99.99%) and clinical specificity is 99.8% (95% confidence interval 98.92%–100%).

A strong positive anti-HBs test may be associated with:

  • Successful hepatitis B vaccination

  • Previous hepatitis B infection

A weak positive anti-HBs test may be associated with:

  • The need for booster hepatitis B vaccination

  • Previous hepatitis B infection

A negative anti-HBs test may be associated with:

  • Unsuccessful hepatitis B vaccination

  • Susceptibility to hepatitis B infections

Other Considerations

About 10% of adults do not respond well to the hepatitis B vaccine. The exact reasons for this are in many cases unclear. Age over 40 years, obesity, smoking and chronic disease might lower the response rate to vaccination. If you test negative for anti-HBs after repeated vaccination attempts, you are recommended to contact your GP for further investigations.


World Health Organization (‎2017)‎. Hepatitis B vaccines: WHO position paper – July 2017. Weekly Epidemiological Record, 92 (‎27)‎, 369 - 392. World Health Organization. https://apps.who.int/iris/handle/10665/255873