What to do with a patient with Hepatitis B surface antibody (HBsAb) quantitation result of less than 3.5 milli-international units per milliliter (mIU/mL)?

Management of Patient with Hepatitis B Surface Antibody <3.5 mIU/mL

A patient with hepatitis B surface antibody (HBsAb) level less than 3.5 mIU/mL should receive revaccination with a hepatitis B vaccine dose, as this level indicates inadequate protection against hepatitis B virus infection.

Understanding the Result

A hepatitis B surface antibody (HBsAb) level less than 3.5 mIU/mL indicates:

• Non-protective immunity against hepatitis B virus (HBV) infection
• Levels ≥10 mIU/mL are generally considered protective 1
• The patient either:
  • Has never been vaccinated
  • Was previously vaccinated but did not develop adequate antibody response
  • Had waning antibody levels after previous vaccination

Management Algorithm

Step 1: Assess Vaccination History and Risk Factors

• Determine if the patient has received a complete hepatitis B vaccination series
• Assess risk factors for HBV exposure (healthcare worker, sexual contacts of HBsAg-positive persons, etc.)

Step 2: Additional Testing

• Consider testing for HBsAg and total anti-HBc to rule out current or past HBV infection 1
• Interpretation of serologic markers:
  • If HBsAg negative, anti-HBc negative: Never infected (susceptible)
  • If HBsAg positive: Current HBV infection
  • If HBsAg negative, anti-HBc positive, anti-HBs negative: Past infection or "low-level" chronic infection 1

Step 3: Management Based on Previous Vaccination Status

For Previously Vaccinated Persons:

1. Administer one additional dose of hepatitis B vaccine 1
2. Test for anti-HBs 1-2 months after vaccination
3. If anti-HBs remains <10 mIU/mL after this dose:
   • Administer 2 more doses of hepatitis B vaccine to complete a second series
   • Test anti-HBs 1-2 months after final dose 1
4. If anti-HBs remains <10 mIU/mL after a complete second series (total 6 doses):
   • Consider the person a "non-responder"
   • Test for HBsAg to rule out chronic HBV infection
   • Counsel about precautions to prevent HBV infection
   • Need for HBIG prophylaxis after any known exposure to HBsAg-positive blood 1

For Unvaccinated Persons:

1. Initiate the complete hepatitis B vaccine series (typically 3 doses at 0,1, and 6 months) 1
2. Test for anti-HBs 1-2 months after completing the series

Special Considerations

For Healthcare Workers

• Healthcare institutions should ensure all HCPs with anti-HBs <10 mIU/mL receive additional vaccination 1
• This helps ensure protection in case of occupational exposure to HBV-containing blood or body fluids

For Immunocompromised Patients

• May require annual testing to assess anti-HBs concentrations 1
• May need more frequent booster doses to maintain immunity

For Hemodialysis Patients

• Should receive annual anti-HBs testing
• Administer booster dose when anti-HBs levels decline to <10 mIU/mL 1

Common Pitfalls to Avoid

1. Not distinguishing between vaccination response and natural immunity:

   • Anti-HBs positive with anti-HBc negative indicates vaccine-derived immunity
   • Anti-HBs positive with anti-HBc positive indicates immunity from natural infection 1

2. Misinterpreting low positive anti-HBs results:

   • Different assays have different cutoff values
   • Refer to the specific test's package insert for accurate interpretation 1

3. Delaying revaccination:

   • Non-protective antibody levels leave patients vulnerable to HBV infection
   • Prompt revaccination is essential, especially for high-risk individuals

4. Not completing post-vaccination serologic testing:

   • Testing should be performed 1-2 months after final dose
   • This confirms protective immunity has been achieved 1

By following this approach, you can ensure appropriate management of patients with non-protective hepatitis B surface antibody levels and reduce their risk of HBV infection.