Can a 29-month-old child receive the 2nd dose of Hepatitis A (Hep A) vaccine?

Hepatitis A Vaccination for a 29-Month-Old Child

Yes, a 29-month-old child should receive the second dose of Hepatitis A vaccine, as long as at least 6 months have passed since the first dose. 1

Timing of Second Dose

The Hepatitis A vaccine for children is administered in a 2-dose series:

• First dose: Given at 12-23 months of age
• Second dose: Should be administered 6-18 months after the first dose 1

For the specific vaccines:

• Havrix: Second dose should be given 6-12 months after the first dose
• Vaqta: Second dose can be administered 6-18 months after the first dose 1

Immune Response Considerations

Clinical studies demonstrate excellent immune response in children who receive their second dose at the appropriate interval:

• One month after receiving the second dose of Hepatitis A vaccine at the recommended interval, nearly 100% of children develop protective antibody levels 2
• Children aged 23-25 months who received Hepatitis A vaccine on a 0- and 6-month schedule showed 100% vaccine response with high geometric mean antibody titers (1,911 mIU/mL) 2

Important Considerations

• Do not restart the vaccine series regardless of the time that has elapsed between doses 1
• If the immunization schedule is interrupted, only administer the required dose rather than restarting the series 1
• The second dose is crucial for long-term immunity 1

Potential Pitfalls to Avoid

1. Never administer the second dose earlier than 6 months after the first dose, as this may result in suboptimal immune response 3

2. Don't confuse postexposure prophylaxis with routine vaccination:

   • While a single dose may be sufficient for postexposure prophylaxis
   • Two doses at least 6 months apart are required for long-term immunity 3

3. Don't delay unnecessarily:

   • Although the series doesn't need to be restarted if delayed, completing the series provides optimal protection
   • Studies show that when the booster dose was delayed until 1 year after the initial dose, 95.2% of subjects remained seropositive, and all subjects developed full protection after receiving the second dose 2

Storage and Administration

• Administer the vaccine intramuscularly
• Store between 2-8°C (36-46°F)
• Do not freeze the vaccine as this will destroy potency 1

In summary, a 29-month-old child is at an appropriate age to receive the second dose of Hepatitis A vaccine, provided at least 6 months have passed since the first dose.