Hepatitis A Vaccination Schedule for Adults
For adults requiring hepatitis A protection, administer a 2-dose series of single-antigen vaccine (Havrix or Vaqta) at month 0 and month 6–12 (Havrix) or month 6–18 (Vaqta), or alternatively use the combined hepatitis A/B vaccine (Twinrix) as a 3-dose series at months 0,1, and 6 when protection against both viruses is indicated. 1
Standard Single-Antigen Hepatitis A Vaccine Schedules
The ACIP recommends the following standard regimens for adults:
- Havrix: 2 doses administered at month 0 and month 6–12 1
- Vaqta: 2 doses administered at month 0 and month 6–18 1
Both vaccines provide excellent seroprotection, with virtually 100% of recipients achieving protective antibody levels after completing the 2-dose series. 1 The first dose should ideally be given at least 2 weeks before anticipated exposure (such as international travel) to ensure adequate immune response. 2
Combined Hepatitis A and B Vaccine (Twinrix)
When protection against both hepatitis A and B is clinically indicated, Twinrix offers two scheduling options:
Standard Schedule
- 3 doses at months 0,1, and 6 1
- Each 1 mL dose contains 720 EL.U. of hepatitis A antigen and 20 µg of hepatitis B surface antigen 2
Accelerated Schedule (for rapid protection)
- 4 doses administered on day 0, day 7, and day 21–30, followed by a mandatory booster at month 12 1, 2
- This accelerated regimen is particularly useful for last-minute travelers or individuals requiring urgent protection 3
- The 12-month booster is essential and must not be omitted, as it is required for durable long-term immunity 2
After the first two doses of the standard Twinrix schedule (months 0 and 1), most adults achieve substantial immunity against both viruses, allowing travel without waiting for the third dose. 2
Who Should Receive Hepatitis A Vaccination
The ACIP recommends hepatitis A vaccination for the following populations:
- Persons experiencing homelessness (added as an indication in October 2018) 1
- Men who have sex with men 1
- Persons who use injection or noninjection drugs 1
- Persons with chronic liver disease or clotting factor disorders 1
- Travelers to countries with high or intermediate hepatitis A endemicity 1
- Persons with close personal contact with an international adoptee during the first 60 days after arrival from an endemic country 1
- Laboratory workers handling hepatitis A virus or nonhuman primates infected with the virus 1
- Any person seeking protection from hepatitis A, regardless of risk factors 1
Immunogenicity and Timing
Within 1 month of receiving the first dose, approximately 97% of children/adolescents and 95% of adults develop protective antibody concentrations, with the second dose resulting in virtually 100% protection. 1 The vaccine is highly effective at preventing hepatitis A infection and severe disease.
Key Clinical Pitfalls to Avoid
Do not use Twinrix solely for hepatitis A vaccination when the patient has no indication for hepatitis B protection, as this exposes them to unnecessary hepatitis B antigen. 2 Use single-antigen hepatitis A vaccine (Havrix or Vaqta) in these cases.
Do not omit the 12-month booster when using the accelerated Twinrix schedule (day 0,7,21–30), as this dose is mandatory for long-term immunity. 2
Do not delay vaccination in eligible populations. The vaccine should be administered as soon as an indication is identified, particularly for travelers who should receive the first dose at least 2 weeks before departure. 2
Do not restart an interrupted series. If the hepatitis A vaccination schedule is interrupted, simply continue with the next dose when the patient returns—there is no maximum interval between doses. 2