What is the recommended hepatitis B (HB) titre for Hepatitis B Immunoglobulin (HBIG) administration?

Recommended Hepatitis B Titre for HBIG Administration

The recommended hepatitis B titre for Hepatitis B Immunoglobulin (HBIG) administration is indicated when anti-HBs levels are less than 10 mIU/mL in exposed individuals.

Understanding HBIG and Anti-HBs Titres

Hepatitis B Immune Globulin (HBIG) is a purified solution of human immunoglobulin with high titres of antibody to hepatitis B surface antigen (anti-HBs). It provides temporary protection (3-6 months) from HBV infection and is typically used as post-exposure prophylaxis (PEP) in specific situations 1.

The anti-HBs titre threshold of 10 mIU/mL is considered the critical value for determining protection against HBV infection:

• Anti-HBs ≥10 mIU/mL: Considered protective against HBV infection
• Anti-HBs <10 mIU/mL: Considered non-protective, requiring HBIG administration in exposure scenarios

Indications for HBIG Administration

HBIG is administered in the following scenarios when anti-HBs levels are <10 mIU/mL:

1. Unvaccinated or incompletely vaccinated persons exposed to HBsAg-positive source 1

   • Should receive HBIG (0.06 mL/kg body weight) as soon as possible after exposure (preferably within 24 hours)
   • Should simultaneously begin or complete hepatitis B vaccine series

2. Previously vaccinated persons who are non-responders (anti-HBs <10 mIU/mL after complete vaccination series) 1

   • Should receive 1 dose of HBIG and begin revaccination if exposed to HBsAg-positive source
   • Those who failed to respond to two complete vaccine series should receive 2 doses of HBIG, 1 month apart

3. Perinatal exposure of infants born to HBsAg-positive mothers 2

4. Sexual contact with HBsAg-positive persons 2

5. Post-liver transplantation prophylaxis for patients with prior HBV infection 2

Dosage and Administration

• The recommended dose of HBIG is 0.06 mL/kg body weight 1
• HBIG should be administered intramuscularly
• When administered with hepatitis B vaccine, HBIG should be given at a separate anatomical site 1

Post-HBIG Monitoring

For individuals who receive HBIG and hepatitis B vaccination:

• Post-vaccination testing should be performed 1-2 months after the final vaccine dose 1
• For those who received HBIG, anti-HBs testing should be delayed until HBIG-derived antibodies are no longer detectable (4-6 months after administration) 1

Important Clinical Considerations

• HBIG provides only temporary protection (3-6 months) and should be used in conjunction with hepatitis B vaccination for long-term protection 1
• The effectiveness of HBIG decreases when administered >7 days after exposure 1
• Vaccinated individuals with documented immunity (anti-HBs ≥10 mIU/mL) do not require HBIG after exposure 1
• While some older guidelines suggested higher protective thresholds (e.g., >100 IU/L) 3, current consensus from more recent guidelines clearly establishes ≥10 mIU/mL as the protective threshold 1

Common Pitfalls to Avoid

1. Delaying HBIG administration - HBIG should be given as soon as possible after exposure (preferably within 24 hours)
2. Administering HBIG and vaccine at the same site - This can reduce immune response to the vaccine 4
3. Relying on anti-HBs testing too soon after HBIG - Testing should be delayed 4-6 months after HBIG administration to avoid detecting passively acquired antibodies
4. Unnecessary revaccination - Immunocompetent persons with documented anti-HBs ≥10 mIU/mL do not need routine booster doses or periodic antibody testing 5

By following these guidelines, clinicians can ensure appropriate use of HBIG for post-exposure prophylaxis against hepatitis B virus infection.