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Questions and Answers
NIP Answers Your Questions
Hepatitis A
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General Questions

  • Is there any evidence that giving Hepatitis A vaccine only (no IG), to travelers with departure date <4 weeks, increases the risk of Hepatitis A infection? I believe that Canada recommends only Hep A vaccine (no IG). Can you comment on this?

    Here are the recommendations from the ACIP regarding traveler vaccination with Hepatitis A vaccine:

    "Travelers who are administered vaccine can be assumed to be protected by 4 weeks after receiving the first vaccine dose and therefore should receive this dose at least 4 weeks before departure. Although according to both vaccines' licensure information, the first dose can be given at least 2 weeks before departure, available data suggest that 40%-45% of vaccinated persons might lack neutralizing antibody at 14 days after receiving the first dose (see Immunogenicity in Adults on page 19). No data are currently available regarding the risk for hepatitis A among persons vaccinated 2-4 weeks before departure. Because protection might not be complete until 4 weeks after vaccination, persons traveling to a high-risk area less than 4 weeks after the initial dose also should be administered IG (0.02 mL/kg), but at a different anatomic injection site. A second vaccine dose administered according to the recommended schedule (Tables 5 and 6) is necessary for long-term protection.

    Travelers who are allergic to a vaccine component or who elect not to receive vaccine should receive a single dose of IG (0.02 mL/kg), which provides effective protection against hepatitis A for up to 3 months (Table 4). Travelers whose travel period exceeds 2 months should be administered IG at 0.06 mL/kg; administration must be repeated if the travel period exceeds 5 months (see Table 4)." Source: Prevention of Hepatitis A Through Active or Passive Immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). (6/26/03)

  • Should a thirty-year-old traveler get the hepatitis A vaccine after having the disease at 7 years of age?

    Once a person has been infected with hepatitis A, they are immune and do not need vaccination. However, if there is any doubt about whether the person actually had hepatitis A, you can either test for immunity or vaccinate them. Since two doses of vaccine are needed, testing may be more cost-effective. (6/26/03)

  • Is anti-HAV IgM antibody detectable in serum after vaccination?

    Yes, the presence of anti-HAV IgM is part of the normal immune response to exposure to hepatitis A virus whether it is wild virus or inactivated vaccine virus. Anti-HAV IgM is detectable in the serum about two weeks after vaccination and can continue to be detected for up to 6 weeks depending on the immune response mounted and the sensitivity of the test. (6/26/03)

  • If a person developed a severe local reaction after the first dose of hepatitis A vaccine, should we draw a titer before deciding whether to give the second dose?

    No. Whether a second dose is contraindicated depends on the nature of the reaction; the response to the first dose is not a factor. A subsequent dose of vaccine is contraindicated if the reaction was a life-threatening, anaphylactic-type reaction. Local reactions, even exaggerated ones, do not contraindicate subsequent doses. (2/12/03)



  • If the 2nd dose of Hepatitis A is given less than 6 months after the 1st dose it is invalid because it was given before the minimum interval. But when should this dose be repeated?

    The repeat dose should be spaced after the invalid dose by the recommended minimum interval, which is 6 months in this case. ACIP General Recommendations (2/13/03)

  • What are the ages to begin use of the adult formulations of Hepatitis A & B vaccines. The adult Hepatitis A dosage is indicated for persons 19 years of age and older. The adult Hepatitis B dosage is indicated for persons 20 years of age and older. Twinrix (hepatitis A & B combination) is licensed for use in persons 18 years of age and older. (6/26/03)

  • If the adult dose of hepatitis A vaccine is indicated for persons 19 years of age and older and the adult dose of hepatitis B vaccine is licensed for 20 years of age and older, why is Twinrix licensed for persons 18 years of age and older?

    Twinrix is licensed for persons 18 years of age and older because this was the population with whom Glaxo SmithKline conducted their clinical trials and the data which they presented to FDA with their licensure application. Twinrix contains a pediatric dose of hepatitis A vaccine and an adult dose of hepatitis B vaccine. The Immunization Action Coalition has produced a one-page fact sheet on hepatitis A and B dosages that you may find helpful, (6/26/03)


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This page last modified on April 22, 2004


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