What marker on Hepatitis B (HB) serology indicates immunity due to vaccination?

Hepatitis B Serology Marker for Vaccine-Induced Immunity

The presence of antibody to hepatitis B surface antigen (anti-HBs) alone, without antibody to hepatitis B core antigen (anti-HBc), is the serologic marker that indicates immunity due to vaccination against hepatitis B virus. 1

Understanding Hepatitis B Serologic Markers

Hepatitis B serologic testing involves several markers that help determine infection status or immunity:

• HBsAg (Hepatitis B Surface Antigen): Indicates active HBV infection
• Anti-HBs (Antibody to HBsAg): Indicates immunity to HBV
• Anti-HBc (Antibody to Hepatitis B Core Antigen): Indicates previous or ongoing HBV infection
• HBeAg (Hepatitis B e Antigen): Correlates with viral replication and high infectivity

Differentiating Natural Immunity from Vaccine-Induced Immunity

The key distinction in serologic patterns:

• Vaccine-induced immunity: Only anti-HBs positive (≥10 mIU/mL), with negative HBsAg and negative anti-HBc 1
• Natural immunity (recovery from infection): Both anti-HBs and anti-HBc positive, with negative HBsAg 1

Clinical Significance

Understanding this serologic pattern is crucial for:

1. Confirming successful vaccination: Anti-HBs levels ≥10 mIU/mL after vaccination are considered protective 1

2. Avoiding misinterpretation:

   • Transient HBsAg positivity can occur for up to 18 days after vaccination but is clinically insignificant 1
   • Anti-HBs can also be detected for several months after hepatitis B immune globulin (HBIG) administration 1

3. Identifying those who need vaccination:

   • Individuals negative for all markers (HBsAg, anti-HBs, anti-HBc) are susceptible to infection and should be vaccinated 1

Potential Pitfalls

• Waning antibody levels: Anti-HBs levels may decline over time after vaccination, but most vaccinated individuals maintain immune memory even when antibody levels fall below detectable levels 2

• Isolated anti-HBc: Some individuals show only anti-HBc positivity, which could represent:

  • Past infection with waning anti-HBs levels
  • False-positive result
  • Occult HBV infection (rare)

  These individuals often show an anamnestic response (rapid rise in anti-HBs) after a single booster dose of hepatitis B vaccine 3, 4

• False reassurance: Having anti-HBs from recent HBIG administration rather than from vaccination or natural immunity might provide temporary passive immunity but not long-term protection 1

By identifying the presence of isolated anti-HBs (without anti-HBc), clinicians can confidently determine that a patient has immunity specifically from vaccination rather than from prior natural infection.