What is the recommended regimen for the hepatitis A vaccine (HAV)

Hepatitis A Vaccine Regimen

All children in the United States should receive a 2-dose hepatitis A vaccine series starting at 12-23 months of age, with the second dose administered 6-12 months later for Havrix or 6-18 months later for Vaqta. 1, 2

Standard Vaccination Schedule by Age

Children (Primary Recommendation)

• First dose: Administer at 12-23 months of age 1, 2
• Second dose timing:
  • Havrix: 6-12 months after first dose 1, 2
  • Vaqta: 6-18 months after first dose 1, 2
• Dosing: 0.5 mL (pediatric formulation) administered intramuscularly 1

Adults

• First dose: Administer as soon as indicated 2
• Second dose timing:
  • Havrix: 6-12 months after first dose 2
  • Vaqta: 6-18 months after first dose 2
• Dosing: 1.0 mL administered intramuscularly 3

Combination Vaccine (Twinrix)

• Schedule: 3-dose series at 0,1, and 6 months 1
• Use: For combined hepatitis A and B protection 1

Administration Guidelines

The vaccine must be administered intramuscularly in the deltoid muscle, with needle length appropriate for patient age and size. 1, 2

• Shake vaccine well before administration to achieve a slightly opaque, white-colored suspension 1, 2
• Different brands (Havrix and Vaqta) are interchangeable for completing the series 1, 2
• If the schedule is interrupted, resume with the next required dose without restarting the series 1, 2

Special Populations

Immunocompromised Patients and Chronic Liver Disease

These patients should receive the standard 2-dose vaccine series on the same schedule as immunocompetent individuals. 1, 2

• Immunocompromising conditions are NOT a contraindication to vaccination 1
• The vaccine is inactivated and poses no increased safety risk 1
• For postexposure prophylaxis in this population, both vaccine AND immune globulin (0.1 mL/kg) must be given simultaneously at different anatomic sites 1, 2

International Travelers

Travelers to endemic areas should receive the first dose as soon as travel is considered, ideally at least 4 weeks before departure. 1, 2

• Protection is reliably present by 4 weeks after the first dose 1
• May provide protection as early as 2 weeks after immunization 1
• Complete the 2-dose series according to standard schedule for long-term immunity 2

Special consideration for infants 6-11 months traveling internationally:

• Administer one dose before travel 1, 2
• This dose does NOT count toward the routine 2-dose series 1
• Begin the standard 2-dose series at 12 months of age 1

High-Risk Groups Requiring Vaccination

• Men who have sex with men 1
• Users of injectable or non-injectable illicit drugs 1
• Persons working with hepatitis A virus or non-human primates 3
• Recipients of clotting factors 1

Postexposure Prophylaxis

For healthy persons aged 12 months to 40 years exposed within the past 14 days: administer one dose of hepatitis A vaccine as soon as possible. 1, 2

Age-Specific PEP Recommendations

Infants <12 months:

• Give immune globulin (0.1 mL/kg) only, NOT vaccine 1
• MMR and varicella vaccines must be delayed at least 3 months after IG administration 1

Ages 12 months to 40 years (healthy):

• Give one dose of hepatitis A vaccine 1, 2
• No immune globulin needed 1

Ages >40 years (healthy):

• Give one dose of hepatitis A vaccine 1, 2
• Consider adding immune globulin (0.1 mL/kg) based on provider's risk assessment 1, 2
• If both are given, administer at different anatomic sites 1

Immunocompromised or chronic liver disease (≥12 months):

• Give BOTH hepatitis A vaccine AND immune globulin (0.1 mL/kg) simultaneously at different anatomic sites 1, 2

Important PEP Caveats

• The second dose is NOT required for postexposure prophylaxis efficacy 1
• However, complete the 2-dose series (second dose at least 6 months after first) for long-term immunity 1, 2
• Never administer the second dose sooner than 6 months after the first, regardless of exposure risk 1

Contraindications and Precautions

Absolute contraindications:

• Life-threatening allergic reaction to a previous dose 1
• Severe allergy to any vaccine component (aluminum hydroxide, phenoxyethanol) 1

For contraindicated patients exposed to HAV:

• Use immune globulin (0.1 mL/kg) instead of vaccine 1

Storage Requirements

Store vaccine between 2°C and 8°C (36°F and 46°F); never freeze. 1, 2

• Freezing destroys vaccine potency 1, 2
• Vaccine tolerates storage up to 37°C (98°F) for up to 1 week without affecting immunogenicity or reactogenicity 1

Testing Recommendations

Routine serologic testing before or after vaccination is NOT recommended for the general population. 1, 2