Role of Hepatitis B Immunoglobulins (HBIG) in Preventing HBV Infection
Hepatitis B immunoglobulin (HBIG) is highly effective in preventing HBV infection when administered promptly after exposure, particularly when combined with hepatitis B vaccination, providing both immediate and long-term protection against HBV infection. 1
Mechanism and Efficacy
HBIG provides passive immunization by delivering pre-formed antibodies against hepatitis B surface antigen (HBsAg). Key characteristics include:
- Provides temporary protection lasting 3-6 months 1, 2
- Detectable antibody levels typically persist for approximately 2 months 2
- Mean half-life ranges between 17.5-25 days 2
- When used alone, HBIG is approximately 75% effective in preventing HBV infection after percutaneous exposure 2
Clinical Indications for HBIG
HBIG is indicated for post-exposure prophylaxis in the following situations:
1. Perinatal Exposure
- For infants born to HBsAg-positive mothers, especially if the mother is HBeAg-positive 2
- Combined approach (HBIG + vaccine) is 85-95% effective in preventing the HBV carrier state 2
- HBIG alone has only 50% efficacy in this setting 2
- Administration should occur as soon as possible after birth 1
2. Percutaneous or Mucosal Exposure to HBsAg-positive Blood/Body Fluids
- For unvaccinated persons: HBIG (0.06 mL/kg) + first dose of hepatitis B vaccine 1
- For vaccinated persons with unknown response status: Test for anti-HBs and administer HBIG if levels are <10 mIU/mL and source is HBsAg-positive 1
- For known non-responders to vaccination: HBIG + hepatitis B vaccine 1
- Two-dose regimen of HBIG (one at exposure, one a month later) is about 75% effective 2
3. Sexual Exposure to HBsAg-positive Persons
- Single dose of HBIG within 2 weeks of last sexual exposure is 75% effective 2
- Should be followed by hepatitis B vaccination 1
4. Household Exposure to Persons with Acute HBV Infection
- Particularly important for infants <12 months of age 2
- Combined HBIG and hepatitis B vaccine recommended 1, 2
Administration Guidelines
Dosing
- Standard dose: 0.06 mL/kg body weight 1
- Timing: As soon as possible after exposure, preferably within 24 hours 1
- Route: Intramuscular injection 2
Combination with Hepatitis B Vaccine
- HBIG should be administered simultaneously with hepatitis B vaccine at separate anatomic sites 1
- Combined approach provides both immediate (HBIG) and long-term (vaccine) protection 2
- HBIG does not interfere with the immune response to hepatitis B vaccine 2
Special Considerations
Healthcare Workers
- For unvaccinated healthcare workers with exposure to HBsAg-positive blood: HBIG + complete vaccine series 1
- For previously vaccinated healthcare workers with anti-HBs <10 mIU/mL: HBIG + vaccine booster 1
- For non-responders after two complete vaccine series: Two doses of HBIG (one immediately, one at 1 month) 1
Liver Transplantation
- HBIG is indicated for liver transplantation patients to prevent HBV recurrence 3
Common Pitfalls and Caveats
Delayed administration: Efficacy decreases with time - HBIG should be administered as soon as possible after exposure (preferably within 24 hours) 1
Relying on HBIG alone: While effective, combining HBIG with hepatitis B vaccination provides superior protection and long-term immunity 1, 2
Failure to complete vaccination: After initial HBIG, completing the full hepatitis B vaccine series is essential for long-term protection 1
Missing follow-up testing: For healthcare workers, post-vaccination testing is important to confirm adequate antibody response 1
Overlooking pre-exposure vaccination: Pre-exposure vaccination remains the most effective strategy for preventing HBV infection in high-risk individuals 1
HBIG provides a critical tool for post-exposure prophylaxis against HBV infection, particularly when combined with hepatitis B vaccination. Its prompt administration after exposure can significantly reduce the risk of HBV infection and its long-term consequences.