What is the most efficacious vaccine for preventing hepatitis A?

Most Efficacious Vaccine for Preventing Hepatitis A

All licensed inactivated hepatitis A vaccines (HAVRIX, VAQTA, and TWINRIX) are highly efficacious with similar protective effects, with studies showing 94-100% efficacy in preventing clinical hepatitis A infection. 1

Available Hepatitis A Vaccines

Single-Antigen Vaccines

1. HAVRIX (GlaxoSmithKline)

   • Adults (≥19 years): 1,440 EL.U. per dose in a 2-dose schedule
   • Children/adolescents (12 months-18 years): 720 EL.U. per dose in a 2-dose schedule
   • Contains 2-phenoxyethanol as a preservative 1, 2

2. VAQTA (Merck & Co.)

   • Adults (≥19 years): 50 U per dose in a 2-dose schedule
   • Children/adolescents (12 months-18 years): 25 U per dose in a 2-dose schedule
   • Formulated without a preservative 1, 2

Combination Vaccine

1. TWINRIX (GlaxoSmithKline)
   • Combined hepatitis A and hepatitis B vaccine
   • Contains 720 EL.U. of hepatitis A antigen (half of the HAVRIX adult dose)
   • Licensed only for persons ≥18 years
   • Administered as a 3-dose series (0,1, and 6 months) 1, 3

Efficacy Data

• HAVRIX demonstrated 94% efficacy (95% CI: 79%-99%) in preventing clinical hepatitis A in a large trial in Thailand involving approximately 40,000 children 1, 2

• VAQTA showed 100% efficacy (lower bound of 95% CI: 87%) after administration of a single dose in a trial involving approximately 1,000 children in New York 1

• All licensed vaccines produce seroprotection rates of 94-100% after one dose and 100% after the second dose 1, 2

Immunogenicity

• After a single dose, protective antibody levels develop in:

  • 94-100% of adults within 1 month
  • 97-100% of children and adolescents within 1 month 1

• Timing of antibody development:

  • 54-62% develop neutralizing antibody within 14 days after first dose
  • 94-100% develop neutralizing antibody within 1 month 1

• After the second dose, 100% of recipients develop protective antibody levels 1, 2

Dosing Schedule

Standard schedule for all hepatitis A vaccines is a two-dose series:

• First dose at initial visit
• Second (booster) dose 6-12 months later 1, 2

Recent evidence suggests that a single dose of inactivated hepatitis A vaccine may provide long-term protection, with studies showing that the immune response to a booster dose is independent of the time since initial vaccination, even up to 10.67 years later 1. This indicates potential flexibility in booster administration timing.

Special Considerations

• Interchangeability: Evidence suggests hepatitis A vaccines are interchangeable. A study showed that using Avaxim as a second dose following first doses of either VAQTA or HAVRIX produced similar antibody responses compared to using the same vaccine for both doses 4

• Pregnancy: Hepatitis A vaccines are considered safe for use in pregnancy 5

• Immunocompromised persons: May have diminished immune response to vaccination 2

• Post-exposure prophylaxis: While immune globulin has traditionally been used for post-exposure prophylaxis, hepatitis A vaccine may also be effective when administered shortly after exposure 1

Practical Recommendations

1. For most individuals, any of the licensed inactivated hepatitis A vaccines will provide excellent protection when administered according to the recommended schedule

2. For adults who need protection against both hepatitis A and B, TWINRIX offers the convenience of combined protection

3. For those concerned about preservatives, VAQTA is formulated without preservatives

4. For rapid protection (e.g., imminent travel to endemic areas), vaccines induce protective antibody levels in most recipients within 2-4 weeks after a single dose 6, 7

The choice between vaccines should be based on availability, age of recipient, need for combined hepatitis B protection, and preservative preferences, as all licensed vaccines provide similar high levels of protection against hepatitis A virus infection.