What is the recommended course of action for a healthy adult patient with a low titre level after receiving the hepatitis B (HB) vaccination?

Management of Low Hepatitis B Antibody Titers After Vaccination in Healthy Adults

For healthy adults with low anti-HBs titers (<10 mIU/mL) after completing a standard hepatitis B vaccination series, administer a single additional vaccine dose first, then test antibody levels 1-2 months later—if still non-responsive, complete a second full 3-dose series. 1

Initial Assessment and Testing

• Test anti-HBs levels 1-2 months after completing the initial 3-dose vaccination series to determine if protective immunity (≥10 mIU/mL) has been achieved 1
• A non-responder is defined as having anti-HBs <10 mIU/mL after the complete primary series 1
• Before proceeding with revaccination, ensure the patient received the appropriate age-specific dose: for adults ≥20 years, this is 10 μg (Recombivax HB) or 20 μg (Engerix-B) per dose 2

Revaccination Algorithm

Step 1: Single Booster Dose

• Administer one additional dose of hepatitis B vaccine as the first-line approach for non-responders 1
• This single dose produces protective antibody levels in 25-50% of initial non-responders 1
• Test anti-HBs levels 1-2 months after this additional dose 1

Step 2: Second Complete Series (If Still Non-Responsive)

• If anti-HBs remains <10 mIU/mL after the single booster, complete a second full 3-dose series using the standard 0,1, and 6-month schedule 1
• This approach achieves seroprotection in 44-100% of non-responders 1, 2
• Perform final anti-HBs testing 1-2 months after completing the second series to document response status 1

Step 3: Persistent Non-Responders

• Do not administer more than two complete vaccine series (total of 6-7 doses including the initial booster) 1
• Test for HBsAg to rule out chronic HBV infection in persistent non-responders 1
• Counsel these individuals that if exposed to HBV in the future, they should receive two doses of hepatitis B immune globulin (HBIG) 1

Important Clinical Considerations

Factors Affecting Response

• Age >40 years significantly reduces vaccine response, with only 75% of people aged 60+ developing protective antibodies compared to >95% in younger adults 1, 3
• Obesity, smoking, and genetic factors also contribute to non-response 1
• The GMT among seroconverters over age 40 is substantially lower (610 mIU/mL) compared to younger adults 3

Critical Distinction: Non-Response vs. Waning Immunity

• Immunocompetent adults who previously achieved anti-HBs ≥10 mIU/mL do NOT need routine antibody testing or booster doses, even if titers subsequently fall below 10 mIU/mL 2, 4
• Immunological memory persists for at least 15 years in immunocompetent individuals, providing protection through anamnestic response upon exposure 4
• Studies demonstrate that 85% of healthy vaccinees maintain protection 6.5 years post-vaccination, with robust anamnestic responses (geometric mean titer 609 mIU/mL) to booster doses 5

When NOT to Revaccinate

• Persons with documented completion of a vaccination series at any point should not receive additional doses unless they fall into specific high-risk categories 2
• Only accept dated vaccination records as evidence of prior vaccination 2
• Periodic testing and boosters are unnecessary for immunocompetent persons 2

Common Pitfalls to Avoid

• Do not confuse initial non-response with waning immunity: A person who never achieved anti-HBs ≥10 mIU/mL requires revaccination, while someone whose titers declined after initially achieving protective levels does not 1, 4
• Ensure proper vaccine administration: Hepatitis B vaccine must be given intramuscularly in the deltoid muscle for adults; buttock administration results in substantially lower immunogenicity 2
• Avoid intradermal administration: This route produces inadequate antibody responses (55-81% seroconversion vs. >90% with intramuscular) and should only be used in research protocols 2
• Do not delay testing after HBIG administration: If HBIG is given, wait approximately 6 months before testing anti-HBs, as passive antibody will interfere with results 1

Special Populations Requiring Different Management

While this guidance applies to healthy adults, note that immunocompromised patients, hemodialysis patients, and those with chronic liver disease require different dosing schedules, regular antibody monitoring, and booster doses when titers fall below 10 mIU/mL 2, 6, 7, 4. These populations should be managed according to specific guidelines for their conditions.