What it measures
- Hepatitis B core antibody (anti-HBc)
Past or current infection?
Core antibodies are only made after a real hepatitis B infection, never after vaccination. A positive result means you’ve been infected at some point. Together with the surface antigen test, it shows whether the infection has cleared or is ongoing.
This is important before treatments that suppress the immune system, such as chemotherapy or some arthritis medicines, which can reactivate an old infection.
Who it’s for
- Working out whether immunity comes from vaccination or past infection
- Screening before some medical treatments
- Possible past exposure to hepatitis B
How to prepare
- Drink plenty of water beforehand; it makes the sample quicker and easier to take.
- You don’t need to fast.
Hepatitis B Core Antibody (HBcAb) Blood Test: your questions
Will my hepatitis B vaccine make this test positive?
No. The vaccine only produces surface antibodies (anti-HBs). Core antibodies only appear after a natural infection.
Information on this page is general and doesn’t replace advice from your GP, midwife or consultant. If you feel unwell or are worried about symptoms, contact your GP, call NHS 111 or, in an emergency, 999.