What tests are required after a hepatitis B (HBV) exposure?

Testing Required After Hepatitis B Exposure

After hepatitis B exposure, immediately test the source patient for HBsAg (if possible), determine the exposed person's vaccination status and anti-HBs level, and perform baseline testing on the exposed person if they are unvaccinated or have inadequate immunity. 1

Immediate Testing Protocol

Source Patient Testing

• Test the source patient for HBsAg to determine if they are hepatitis B surface antigen positive, which directly impacts prophylaxis decisions 1
• If the source patient cannot be identified or refuses testing, base management decisions on the likelihood of HBV exposure considering the exposure type and source 1
• FDA-approved rapid testing methods are available for expedited results 1

Exposed Person Testing

For unvaccinated or incompletely vaccinated individuals:

• Obtain baseline total anti-HBc (hepatitis B core antibody) immediately after exposure 1
• This baseline testing helps establish whether prior HBV infection existed before the exposure 1

For previously vaccinated individuals with unknown immunity:

• Test for anti-HBs (hepatitis B surface antibody) immediately to determine current immunity status 1
• Anti-HBs ≥10 mIU/mL indicates protective immunity and no further treatment is needed 1
• Anti-HBs <10 mIU/mL requires both prophylaxis and completion of testing protocol 1

Follow-Up Testing at 6 Months

For exposed persons who were unvaccinated or had inadequate immunity at the time of exposure:

• Perform HBsAg testing approximately 6 months post-exposure to detect chronic infection 1
• Perform total anti-HBc testing at 6 months to detect any HBV infection that may have occurred 1
• This dual testing approach at 6 months is critical because it identifies both acute infections that progressed to chronic infection (HBsAg positive) and resolved infections (anti-HBc positive, HBsAg negative) 1

For vaccinated persons who received a booster or completed vaccination series:

• Test anti-HBs 1-2 months after the final vaccine dose to document vaccine response for future exposures 1
• This is particularly important for healthcare personnel to establish their immune status in medical records 1

Additional Testing Considerations

HIV and Hepatitis C Co-Testing

• Test the exposed person for HIV antibody at baseline and repeat at 6 months post-exposure 1
• Test for hepatitis C antibody at baseline and repeat at 6 months post-exposure 1
• These bloodborne pathogens often share transmission routes with HBV, making co-testing essential 1

Documentation Requirements

• Document the exposure type (percutaneous, mucosal, sexual contact), blood involvement, and injury extent 1
• Maintain written records of all vaccination dates and serologic test results for future reference 1

Common Pitfalls to Avoid

• Do not delay baseline testing while waiting for source patient results—obtain exposed person's baseline immediately 1
• Do not skip the 6-month follow-up testing even if prophylaxis was administered, as breakthrough infections can occur 1
• Do not assume immunity based on vaccination history alone without documented anti-HBs levels, as vaccine-induced antibodies wane over time in some individuals 1
• Do not test for anti-HBs too early after vaccination—wait 1-2 months after the final dose for accurate assessment 1