What is the appropriate dose and administration of hepatitis B immune globulin (HBIG) for an adult after a percutaneous (pin‑prick) exposure?

Hepatitis B Immune Globulin Dosing for Needlestick Injury

For an adult after a needlestick exposure, administer HBIG at a dose of 0.06 mL/kg body weight intramuscularly as soon as possible, preferably within 24 hours of exposure. 1

Immediate Management Algorithm

The appropriate dose and timing depend on your vaccination status and the source patient's HBsAg status:

If You Are Unvaccinated or Incompletely Vaccinated

• Administer HBIG 0.06 mL/kg intramuscularly immediately (preferably within 24 hours, though effectiveness up to 7 days is acceptable) 2, 1
• Simultaneously initiate the hepatitis B vaccine series at a separate anatomic site (first dose given at the same time as HBIG, with subsequent doses at 1 and 6 months) 2, 1
• This dual approach applies when the source is HBsAg-positive or unknown high-risk 2, 1

If You Are Vaccinated with Known Immunity

• No HBIG or additional vaccination is needed if you have documented anti-HBs ≥10 mIU/mL 2, 3
• This is the most common scenario for healthcare workers with complete vaccination series and documented response 3

If You Are Vaccinated but Response Status Unknown

• Draw blood immediately for anti-HBs testing, but do not wait for results 3, 4
• If the source is HBsAg-positive, administer HBIG 0.06 mL/kg immediately plus one vaccine booster dose at a separate site 2, 1
• The risk of treating someone who may already be immune is negligible compared to the risk of not treating someone who lacks protection 3

If You Are a Known Vaccine Non-Responder

• Administer HBIG 0.06 mL/kg immediately if source is HBsAg-positive 2, 1
• Consider either: (1) a second dose of HBIG one month later, OR (2) HBIG plus initiation of a second complete 3-dose vaccine series 2, 1

Critical Timing Considerations

The effectiveness of HBIG decreases markedly after 7 days for percutaneous exposures, making immediate administration essential 2, 1. While guidelines emphasize administration within 24 hours, a Korean multicenter study of 143 healthcare workers found that HBIG given between 24 hours and 7 days post-exposure may be as effective as administration within 24 hours, with no seroconversions occurring in either group 5. However, do not delay beyond 7 days, as efficacy beyond this point is unclear 1.

Administration Details

• Inject intramuscularly in the deltoid muscle 2
• Use a separate anatomic site if administering vaccine simultaneously to avoid interference 1
• Maximum single dose is 5 mL for weight-based dosing in very large adults 2

Follow-Up Testing Considerations

• If you received HBIG, delay post-vaccination anti-HBs testing until 4-6 months after administration to avoid detecting passively acquired antibodies from the immunoglobulin 2, 3
• Perform anti-HBs testing 1-2 months after completing the vaccine series (if HBIG was not given) to document protective levels ≥10 mIU/mL 2, 6

Common Pitfalls to Avoid

• Never delay HBIG administration while awaiting serologic test results when the source is HBsAg-positive and your immunity status is unknown 3, 4
• Do not administer HBIG and vaccine at the same injection site, as this may reduce vaccine immunogenicity 4, 1
• Do not assume immunity without documented anti-HBs testing after vaccination 3
• Do not fail to complete the full 3-dose vaccine series after initiating post-exposure prophylaxis 6

Source Patient Assessment

Immediately identify and test the source patient for HBsAg to guide your management 2, 6. If the source cannot be tested or is unknown, base your decision on the likelihood of HBV exposure considering the type of needle and clinical context 2. For high-risk unknown sources (e.g., needles from sharps containers in high-prevalence settings), treat as if the source were HBsAg-positive 2, 1.