What is the role of Hepatitis B immunoglobulins (HBIG) in preventing Hepatitis B virus (HBV) infection?

Role of Hepatitis B Immunoglobulins in Preventing HBV Infection

Hepatitis B immunoglobulin (HBIG) is most effective when used as an adjunct to hepatitis B vaccination for post-exposure prophylaxis, providing immediate passive immunity while the vaccine develops long-term active immunity.

Mechanism of Action and Effectiveness

HBIG provides passive immunization through high titers of antibodies to hepatitis B surface antigen (anti-HBs). When administered properly:

• HBIG provides temporary protection lasting approximately 3-6 months 1
• Detectable anti-HBs levels typically persist for about 2 months 2
• Passively acquired anti-HBs can be detected for 4-6 months after administration 1

Clinical Indications for HBIG

HBIG is indicated in the following specific scenarios:

1. Acute Exposure to HBsAg-Positive Blood or Body Fluids

• For unvaccinated or incompletely vaccinated persons: Administer HBIG (0.06 mL/kg body weight) AND first dose of hepatitis B vaccine as soon as possible, preferably within 24 hours of exposure 1, 2
• For previously vaccinated persons without documented response: Administer HBIG and hepatitis B vaccine booster 1
• For documented vaccine responders: No HBIG needed (protected by previous vaccination) 1

2. Perinatal Exposure of Infants Born to HBsAg-Positive Mothers

• Combination of HBIG at birth with hepatitis B vaccine series is 85-95% effective in preventing development of the HBV carrier state 2, 3
• HBIG alone has only 50% efficacy, making the combination approach critical 2

3. Sexual Exposure to HBsAg-Positive Persons

• Single dose of HBIG is 75% effective if administered within 2 weeks of last sexual exposure 2
• Should be followed by complete hepatitis B vaccination series 1

4. Household Exposure to Persons with Acute HBV Infection

• Particularly important for infants under 12 months of age 2
• Combination of HBIG and hepatitis B vaccine recommended 1

5. Liver Transplantation

• HBIG is indicated for prophylaxis in liver transplantation 4

Post-Exposure Prophylaxis Protocol

For optimal protection following exposure to HBV:

1. Timing is critical: Administer HBIG as soon as possible after exposure, ideally within 24 hours 1
2. Dosage: Standard dose is 0.06 mL/kg body weight 1, 2
3. Administration: HBIG should be given at a separate anatomical site from the hepatitis B vaccine 1
4. Follow-up: Complete the full hepatitis B vaccine series according to schedule 1

Important Clinical Considerations

• HBIG does not interfere with vaccine response: Administration of HBIG either preceding or concurrent with hepatitis B vaccination does not interfere with the immune response to the vaccine 2
• HBIG is not indicated for treatment: HBIG is for prophylaxis only and not for treatment of established acute or chronic hepatitis B infection 4
• Combination approach is superior: The combination of HBIG plus vaccination provides both immediate and long-term protection and is more effective than either intervention alone 2, 3

Common Pitfalls to Avoid

1. Delayed administration: Effectiveness decreases with time after exposure; HBIG should be administered as soon as possible, preferably within 24 hours 1
2. Relying on HBIG alone: Always combine with hepatitis B vaccination for optimal protection unless the person is a documented vaccine responder 1, 2
3. Inappropriate testing: Testing unvaccinated persons for anti-HBs after exposure is unnecessary and potentially misleading 1
4. Missing follow-up doses: Ensure completion of the full hepatitis B vaccine series after HBIG administration 1

For healthcare workers with occupational exposure, a systematic approach based on vaccination status is essential, with HBIG administration determined by the HBsAg status of the source patient and the anti-HBs status of the exposed individual 1.