Hepatitis A and B vaccination

Hepatitis A Vaccine - Un-A-vailing the Virus

• Type: Inactivated (killed), whole-virus vaccine.
• Administration: Intramuscular (IM) injection.
• Schedule (Routine): All children receive 2 doses:
  • First dose at 12-23 months.
  • Second dose 6-18 months after the first.
• Indications (High-Risk):
  • Travelers to endemic regions.
  • Men who have sex with men (MSM).
  • Users of injection & non-injection illicit drugs.
  • Chronic liver disease (including Hepatitis B or C).

⭐ Post-Exposure Prophylaxis (PEP): For healthy individuals aged 1-40 years, the Hepatitis A vaccine is preferred over immunoglobulin for PEP as it provides long-term active immunity.

Hepatitis B Vaccine - Serology & Strategy

• Mechanism: Recombinant HBsAg vaccine induces production of anti-HBs antibodies.
• Goal: Achieve protective anti-HBs titer ≥10 mIU/mL.
• Schedule: Standard 3-dose series (0, 1, 6 months).

Key Serology:

• Anti-HBs: Immunity from vaccination or prior infection. This is the only positive marker in a successfully vaccinated person.
• HBsAg: Active infection (acute or chronic).
• Anti-HBc: Marker of past or current infection (IgM = acute; IgG = chronic/resolved). Not present after vaccination.

⭐ A vaccinated individual is Anti-HBs positive but Anti-HBc negative. An individual with resolved natural infection is positive for both Anti-HBs and Anti-HBc IgG.

Post-Exposure Management Flowchart

Schedules & Special Cases - The Vax Playbook

• Hepatitis A (HAV) - Inactivated Virus
  • Routine: Children at age 1 (12-23 months). 2-dose series, with doses separated by 6-18 months.
  • High-Risk Adults: Travelers to endemic regions, MSM, IV drug users, chronic liver disease, occupational exposure.
• Hepatitis B (HBV) - Recombinant Subunit
  • Routine Infant: 3-dose series at 0, 1-2, and 6-18 months.
  • High-Risk Adults: Healthcare workers, patients with ESRD/diabetes/HIV/chronic liver disease, partners of HBsAg-positive individuals.
  • ⚠️ Dialysis/Immunocompromised: May require higher vaccine doses or a special formulation (e.g., Heplisav-B) and post-vaccination serologic testing.
• Combination Vaccine (Twinrix: HAV/HBV)
  • For adults ≥18 years.
  • Standard schedule: 3 doses at 0, 1, and 6 months.

⭐ For an infant born to an HBsAg-positive mother, administer both HBV vaccine and Hepatitis B Immune Globulin (HBIG) within 12 hours of birth to prevent vertical transmission.

High‑Yield Points - ⚡ Biggest Takeaways

• The Hepatitis A vaccine is an inactivated virus vaccine; it's recommended for all children at age 1 and for high-risk adults.
• The Hepatitis B vaccine contains recombinant HBsAg and is a key part of routine infant vaccination.
• Post-exposure prophylaxis for Hepatitis A involves the vaccine or immune globulin (IG).
• For Hepatitis B exposure, both HBIG and the vaccine series are crucial.
• Healthcare workers require Hepatitis B vaccination and proof of immunity (anti-HBs titers).