Hepatitis A Vaccine Schedule
The standard hepatitis A vaccine schedule consists of a 2-dose series: an initial dose followed by a booster dose administered 6-12 months later. 12
Age-Specific Dosing
Children and Adolescents (12 months through 18 years)
- Initial dose: 0.5 mL intramuscularly
- Booster dose: 0.5 mL administered 6-12 months after the first dose 2
Adults (≥19 years)
- Initial dose: 1.0 mL intramuscularly
- Booster dose: 1.0 mL administered 6-12 months after the first dose 2
Key Timing Considerations
The second dose should NOT be administered sooner than 6 months after the first dose, regardless of exposure risk. 1 This minimum 6-month interval is critical for optimal long-term immunity.
The booster can be given anytime between 6-12 months after the initial dose, providing some scheduling flexibility without compromising immunogenicity 12.
Special Populations
Infants 6-11 Months (Travel Only)
For infants traveling internationally where hepatitis A protection is needed:
- Give one 0.5 mL dose before travel
- This travel dose does NOT count toward the routine 2-dose series
- Begin the standard 2-dose series at 12 months of age 11
Immunocompromised or Chronic Liver Disease
Follow the same 2-dose schedule (initial dose plus booster at 6-12 months), but these patients may require additional immune globulin depending on exposure circumstances 11
Important Clinical Pearls
Primary immunization should be administered at least 2 weeks prior to expected HAV exposure to allow adequate antibody development 22. Seroconversion occurs in 88-96% of recipients by 2 weeks and 97-100% by 1 month after a single dose 3.
For postexposure prophylaxis, only ONE dose is required for immediate protection—the second dose is not necessary for PEP but should still be completed 6-12 months later for long-term immunity 11.
The vaccine is administered intramuscularly, typically in the deltoid muscle. Never mix hepatitis A vaccine with other vaccines in the same syringe 2.