Can a patient receive Havrix (Hepatitis A vaccine) if their first dose was Vaqta (Hepatitis A vaccine)?

Interchangeability of Havrix and Vaqta for Hepatitis A Vaccination

Yes, a patient can receive Havrix for their second dose if their first dose was Vaqta. The hepatitis A vaccines are interchangeable, and completing the series with a different brand than the initial dose is both safe and effective 1.

Evidence for Interchangeability

According to the American Academy of Pediatrics guidelines, while administration of 2 doses of the same hepatitis A vaccine is preferable, data clearly indicate that the vaccines are interchangeable. The 2-dose series may be completed with either of the vaccine preparations approved for the patient's age group 1.

This recommendation is based on clinical evidence showing:

• Both vaccines contain inactivated hepatitis A virus
• Both vaccines elicit similar immune responses
• Studies have demonstrated comparable immunogenicity when mixing the vaccines

Specific Vaccination Protocol

When completing a mixed-brand hepatitis A vaccination series:

1. Administer Havrix at the appropriate age-based dosage:

   • Ages 1-18 years: 720 ELU in 0.5 mL volume
   • Ages ≥19 years: 1440 ELU in 1.0 mL volume 1

2. Follow the recommended timing for the second dose:

   • For Havrix: 6-12 months after the first dose
   • The original Vaqta schedule would have been 6-18 months between doses 1

3. No need to restart the series - if the immunization schedule is interrupted, only the required immunization needs to be administered 1

Clinical Considerations

• Immunogenicity: Research has shown that a regimen of Havrix followed by Vaqta (or vice versa) is highly immunogenic 2
• Safety profile: When comparing the two vaccines, both have excellent safety profiles, though some studies suggest Vaqta may have fewer local injection site reactions 3
• Protection: Both vaccines provide long-term protection against hepatitis A infection, with protective antibody levels persisting for >40 years after completing the 2-dose series 1

Important Caveats

• Storage requirements are identical for both vaccines (2-8°C/36-46°F) 1
• Neither vaccine should be frozen as this destroys vaccine potency 1
• Pre-vaccination serologic testing is not routinely recommended for children due to low prevalence of prior infection 1
• Post-vaccination serologic testing is not indicated as most persons respond adequately to the vaccine 1

By completing the hepatitis A vaccination series with Havrix after an initial dose of Vaqta, the patient will receive full protection against hepatitis A virus infection, with no compromise in efficacy or safety.