What is the recommended approach for hepatitis B (HB) prophylaxis?

Hepatitis B Prophylaxis

Hepatitis B prophylaxis depends on the clinical scenario: for perinatal exposure, administer both HBIG (0.5 mL) and hepatitis B vaccine within 12-24 hours of birth; for occupational or sexual exposure, use HBIG (0.06 mL/kg) plus vaccine within 24 hours for needlestick injuries or within 14 days for sexual contact; for cancer patients with HBsAg-positive status, initiate entecavir, tenofovir disoproxil fumarate (TDF), or tenofovir alafenamide (TAF) before immunosuppressive therapy. 1, 2

Perinatal Prophylaxis (Infants Born to HBsAg-Positive Mothers)

Combined passive-active immunoprophylaxis is the standard of care for preventing vertical transmission. 1

• Administer HBIG 0.5 mL intramuscularly within 12 hours of birth (efficacy decreases markedly if delayed beyond 48 hours) 1, 2
• Begin hepatitis B vaccine series (first dose 10 μg) within 7 days of birth, preferably within 24 hours 1
• This combination is 85-95% effective in preventing both acute infection and chronic carrier state 1
• Vaccine alone (without HBIG) is 70-95% effective when started within 24 hours 1

Vaccination schedule: Administer at 0,1, and 6 months of age 1, 2

Post-prophylaxis testing: Test for anti-HBs and HBsAg at 9-15 months of age to confirm successful immunoprophylaxis and identify the rare infant who becomes a carrier 1

Long-term protection: Studies demonstrate that properly immunized infants maintain protection for at least 20 years despite declining antibody levels, with no need for booster doses during adolescence 3

Occupational Exposure (Needlestick/Sharp Injuries)

The approach depends on the vaccination status of the exposed healthcare worker and the HBsAg status of the source patient. 1, 2

For Unvaccinated Exposed Persons:

• Source HBsAg-positive: Administer HBIG (0.06 mL/kg, maximum 5 mL) immediately plus begin hepatitis B vaccine series 1, 2
• Source HBsAg-negative or unknown: Begin hepatitis B vaccine series 1

For Previously Vaccinated Persons Who Responded:

• No treatment necessary regardless of source status 1

For Previously Vaccinated Non-Responders:

• Source HBsAg-positive: Give HBIG immediately and in 1 month, or HBIG plus vaccine booster 1, 2
• Source HBsAg-negative: No treatment 1

For Vaccinated Persons with Unknown Response:

• Source HBsAg-positive: Test exposed person for anti-HBs; if negative, give 1 dose HBIG and 1 dose vaccine, then retest at 4-6 months 1

Critical timing: Initiate prophylaxis within 24 hours of exposure for maximum effectiveness 1, 2

Sexual Exposure to HBsAg-Positive Person

• Administer HBIG 0.06 mL/kg as a single dose within 14 days of last sexual contact 1, 2
• Begin hepatitis B vaccine series simultaneously at a different injection site 1, 2
• The vaccine provides long-lasting protection beyond the temporary 3-6 month protection from HBIG 1

Prophylaxis for Cancer Patients Receiving Immunosuppressive Therapy

All cancer patients should be screened with HBsAg, anti-HBc, and anti-HBs before starting anticancer therapy. 1

HBsAg-Positive Patients:

• Initiate antiviral prophylaxis before or simultaneously with immunosuppressive therapy 1
• Use high-barrier agents: entecavir, TDF, or TAF (avoid lamivudine due to resistance) 1
• Continue prophylaxis during therapy and for at least 6 months after completion (12 months for anti-CD20 therapies like rituximab, 18 months for stem cell transplant) 1

HBsAg-Negative, Anti-HBc-Positive Patients:

• For rituximab or stem cell transplant: Initiate prophylaxis with entecavir, TDF, or TAF 1
• For other chemotherapy: Monitor ALT, HBV DNA, and HBsAg every 1-3 months with intent for on-demand therapy 1
• Start preemptive therapy immediately if HBsAg or HBV DNA becomes positive 1

Monitoring during prophylaxis: Check ALT and HBV DNA at baseline and every 6 months during antiviral therapy 1

Vaccination Schedules and Efficacy

Standard three-dose schedule (0,1,6 months) induces protective antibody response in >90% of healthy adults and >95% of infants, children, and adolescents. 1

Administration Details:

• Administer intramuscularly in the deltoid muscle for adults and children 1
• Use anterolateral thigh for neonates and infants 1
• Never inject in the buttock (substantially lower immunogenicity in adults) 1

Alternative Schedules:

• Accelerated schedule (0,1,2,12 months): Provides earlier seroconversion for high-risk individuals while maintaining long-term protection 4
• Schedule (0,1,12 months): Produces higher geometric mean titers (19,912 IU/L) compared to standard schedule (5,846 IU/L), potentially preferable for long-lasting protection 4

Post-Vaccination Testing and Revaccination

Routine post-vaccination testing is not necessary for healthy infants, children, or adolescents. 1, 5

Testing IS Recommended For:

• Infants born to HBsAg-positive mothers (test at 9-15 months) 1
• Dialysis patients and staff 1
• Persons with HIV infection 1
• Healthcare workers with occupational exposure risk 1

Timing of post-vaccination testing: Perform 1-6 months after completion of vaccine series 1

For Non-Responders:

• Revaccination produces adequate antibody response in 15-25% after one additional dose and 30-50% after three additional doses 1
• Consider revaccination with one or more additional doses 1

Duration of Protection and Booster Doses

Immunocompetent individuals who complete the full 3-dose series remain protected for 30 years or more, even when antibody levels decline below detectable levels. 5

• Booster doses are NOT recommended for children and adults with normal immune status 5
• Protection persists through immunologic memory via memory B-cells that rapidly produce antibodies upon exposure 5
• Long-term studies demonstrate intact immunologic memory for at least 9 years, conferring protection against chronic infection even with undetectable anti-HBs 5

Exceptions Requiring Monitoring/Boosters:

• Hemodialysis patients: Require annual antibody testing with booster doses when levels decline 5
• Immunocompromised individuals: May require more frequent monitoring and potential booster doses 5

Common Pitfalls to Avoid

• Do not delay perinatal prophylaxis: HBIG efficacy decreases markedly if not given within 48 hours of birth 1, 2
• Do not use buttock injection site: This substantially reduces vaccine immunogenicity in adults 1
• Do not assume HBsAb indicates immunity when HBsAg is also positive: This represents chronic infection with antibody response, not protective immunity 6
• Do not use lamivudine as first-line prophylaxis: Resistance rates reach up to 70% after 5 years 1, 6
• Do not discontinue antiviral prophylaxis prematurely in cancer patients: This can lead to severe hepatitis flares 6
• Do not assume waning antibody levels indicate loss of protection: Immunologic memory persists despite undetectable anti-HBs in immunocompetent individuals 5, 3