When should Hepatitis B Immunoglobulin (HBIG) be administered after exposure to the Hepatitis B virus?

When to Give Hepatitis B Immunoglobulin (HBIG)

HBIG should be administered as soon as possible after exposure to hepatitis B virus, preferably within 24 hours, and must be given with the hepatitis B vaccine series simultaneously at a separate anatomic site for unvaccinated or incompletely vaccinated individuals exposed to HBsAg-positive sources. 1

Timing of Administration

The effectiveness of HBIG is critically time-dependent:

• Initiate HBIG within 24 hours of exposure for maximum efficacy 1, 2
• Effectiveness diminishes significantly after 7 days for percutaneous exposures (needlestick, bite) 1
• Effectiveness diminishes significantly after 14 days for sexual exposures 1
• For perinatal exposure, HBIG should be given within 12 hours of birth, though protection has been demonstrated when given up to 72 hours after birth 1
• HBIG efficacy decreases markedly if treatment is delayed beyond 48 hours in newborns 3

Clinical Situations Requiring HBIG

1. Perinatal Exposure (Newborns)

For infants born to HBsAg-positive mothers:

• Administer 0.5 mL HBIG intramuscularly within 12 hours of birth (preferably after physiologic stabilization) 1, 3
• Give first dose of hepatitis B vaccine simultaneously at a separate anatomic site within 7 days of birth 1, 3
• This passive-active prophylaxis is 85-95% effective in preventing acute and chronic HBV infection 1

2. Percutaneous or Mucosal Exposure (Needlestick, Bite, Splash)

For unvaccinated persons exposed to HBsAg-positive blood:

• Administer HBIG 0.06 mL/kg body weight intramuscularly as soon as possible 1, 2, 3
• Begin hepatitis B vaccine series simultaneously at a separate site 1, 2

For previously vaccinated persons with unknown antibody response:

• Give HBIG and a hepatitis B vaccine booster dose if the vaccine series was not completed or if previous vaccination occurred without testing 1

For persons with documented immunity (anti-HBs ≥10 mIU/mL):

• No HBIG is required 2

3. Sexual Exposure

For sexual partners of HBsAg-positive persons:

• Administer HBIG 0.06 mL/kg intramuscularly within 14 days of last sexual contact 3, 4
• Begin hepatitis B vaccine series simultaneously 3

4. Household Exposure

For infants <12 months exposed to a primary caregiver with acute hepatitis B:

• Give 0.5 mL HBIG plus hepatitis B vaccine 3

For other household contacts:

• HBIG is not indicated unless they had identifiable blood exposure (e.g., sharing toothbrushes or razors), which should be treated as sexual exposure 3

Who Does NOT Need HBIG

• Persons with documented immunity (anti-HBs ≥10 mIU/mL) after complete vaccination series 2
• Exposure to source with unknown HBsAg status: Give hepatitis B vaccine series only, not HBIG 1
• Persons who completed hepatitis B vaccine series with documented serologic response 1

Administration Guidelines

• Standard adult/child dose: 0.06 mL/kg body weight intramuscularly 1, 2, 3
• Newborn dose: 0.5 mL intramuscularly 1, 3
• Administer at a separate anatomic site from the hepatitis B vaccine 1, 2, 3
• Route: Intramuscular only; never administer intravenously 3

Follow-Up Testing Considerations

• Postvaccination testing should be performed 1-2 months after completing the vaccine series for healthcare personnel and high-risk groups 2, 5
• If HBIG was administered, delay postvaccination testing until 4-6 months after HBIG to avoid detecting passively acquired antibodies 2, 5

Common Pitfalls to Avoid

• Delaying HBIG administration beyond 24 hours, which significantly reduces effectiveness 2, 5
• Not administering both HBIG and vaccine simultaneously when indicated for HBsAg-positive exposures 2, 5
• Failing to complete the full hepatitis B vaccine series after initial post-exposure management 2, 5
• Assuming immunity without documented serologic testing after vaccination 2
• Giving HBIG to persons with documented immunity (anti-HBs ≥10 mIU/mL), which is unnecessary 2
• Administering HBIG and vaccine at the same injection site, which may impair immune response 1