Last edited 06/2018 and last reviewed 03/2022

HBsAg (surface antigen)

  • this is the earliest indicator of HBV appearing 27-41 days after infection
  • may occur before icterus is clinically evident
  • persistence beyond 6 months defines a chronic infection
    • up to 50% of people with extended chronic infection will eventually clear HBsAg.
    • those with resolving acute HBV will clear HBsAg several months after initial infection.

anti-HBsAg (surface antibody)

  • rises once the acute disease is over and convalescence has started
  • levels are rarely high and are undetectable in 10-15% of patients with acute HBV
  • there is a gap of several weeks to months between the disappearance of HBsAg and the appearance of anti-HBs
    • during this period, anti-HBc total is detectable as a marker of HBV infection.


  • indicates acute HBV infection
  • normally present for a shorter time than HBsAg
  • seen soon after transaminase levels peak (i.e. after HBsAg)
  • persistence indicates continued active viral replication and continued infectivity.


  • indicates relatively low infectivity
  • suggests recovery from acute infection
    • but may occur in carriers and is generally a marker of reduced viral replication, indicating a less infectious state (1)

HBcAg - not detectable in the blood.


  • IgM anti-HBc:
    • high titres indicate acute infection
    • low titres indicate ongoing disease, usually chronic active hepatitis
  • IgG anti-HBc:
    • with +ve HBsAg indicates chronic HBV hepatitis
    • with -ve HBsAg indicates infection in the remote past HBV DNA - indicates a continued infectious state. PCR provides a highly sensitive and rapid method for it's detection.

The presence of concomitant infection with hepatitis D should be excluded in all patients with HBV infection.