Hepatitis A Vaccination Timing
All children in the United States should receive their first dose of Hepatitis A vaccine at 12-23 months of age, with the second dose administered at least 6 months later (6-12 months for Havrix, 6-18 months for Vaqta). 1, 2
Routine Childhood Vaccination Schedule
- First dose: Administer at 12-23 months of age 1, 2
- Second dose: Give 6-12 months after the first dose for Havrix, or 6-18 months after the first dose for Vaqta 1, 2
- Critical timing rule: The second dose must not be administered sooner than 6 months after the first dose, regardless of exposure risk 1
- Interchangeability: The two-dose series can be completed with either vaccine preparation (Havrix or Vaqta), though using the same product is preferable 1, 2
Special Timing Considerations
International Travel (Infants 6-11 months)
- Infants traveling internationally should receive one dose before departure 1
- This early dose does not count toward the routine 2-dose series, which must still be initiated at 12 months of age 1
Postexposure Prophylaxis
- Administer within 14 days of exposure for maximum effectiveness 1
- For healthy persons aged 12 months-40 years: Give one dose of vaccine as soon as possible 1
- For persons >40 years: Give one dose of vaccine; immune globulin may also be administered based on provider's risk assessment 1
- For immunocompromised persons or those with chronic liver disease (≥12 months): Give both vaccine and immune globulin simultaneously at different anatomic sites 1, 2
- The second dose is not required for postexposure prophylaxis, but should be given at least 6 months later for long-term immunity 1
Preexposure Protection for Travelers
- Administer the first dose as soon as travel is planned, ideally at least 2 weeks before departure for optimal protection 1, 2
- Protection begins as early as 2 weeks after the first dose, with reliable protection by 4 weeks 1
Important Clinical Pitfalls
Do not restart the series if interrupted - if the vaccination schedule is delayed, simply administer the remaining required dose without restarting 1, 2. This is a common error that leads to unnecessary additional doses.
Avoid premature second dosing - the minimum 6-month interval between doses must be respected, even in high-risk situations or after exposure 1. Giving the second dose earlier does not improve protection and violates the approved schedule.
MMR vaccine interaction - if immune globulin is administered (for infants <12 months or high-risk adults), do not give MMR or varicella vaccines for at least 3 months afterward 1.