Vaccines and Preventable Diseases:
Hepatitis A - Submitted Q&A
Questions submitted during immunization satellite broadcasts or through NIPINFO
For Health Professionals:
General Questions
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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?
Prior to October, 2007, IG was recommended in addition to hepatitis A vaccine for preexposure prophylaxis for travelers to countries with high or intermediate hepatitis A endemicity who were scheduled to depart <4 weeks after receiving the initial vaccine dose. In October, 2007, ACIP updated its recommendations regarding use of vaccine and IG for international travelers, concluding, in part, that "hepatitis A vaccine alone can be . . . recommended for healthy international travelers aged <40 years regardless of their scheduled dates for departure."
- All susceptible persons traveling to or working in countries that have high or intermediate hepatitis A endemicity should be vaccinated or receive IG before departure. Hepatitis A vaccine at the age-appropriate dose is preferred to IG. The first dose of hepatitis A vaccine should be administered as soon as travel is considered.
- One dose of single-antigen hepatitis A vaccine administered at any time before departure can provide adequate protection for most healthy persons.
- Older adults, immunocompromised persons and persons with chronic liver disease or other chronic medical conditions planning to depart to an area in <2 weeks should receive the initial dose of vaccine and also simultaneously can be administered IG (0.02 mL/kg) at a separate anatomic injection site.
- Travelers who elect not to receive vaccine, are aged <12 months, or are allergic to a vaccine component, should receive a single dose of IG (0.02 mL/kg), which provides effective protection for up to 3 months.
Update: Prevention of Hepatitis A After Exposure to Hepatitis A Virus and in International Travelers. Updated Recommendations of the Advisory Committee on Immunization Practices (ACIP), MMWR October 19, 2007 / 56(41);1080-1084 (6/26/03, revised 9/18/07) -
If a person has a documented history of hepatitis A infection, does the person need hepatitis A vaccine?
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. The vaccine will not harm someone who is already immune. (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) -
Are there any projections to require hepatitis A vaccine for healthcare workers?
No. ACIP does not recommend routine hepatitis A vaccination of healthcare workers because as an occupation they have not been shown to be at increased risk. However, many adults have non-occupational indications such as travel, for which the vaccine is indicated. (8/10/06) -
Should we be vaccinating all persons younger than 18 years of age for hepatitis A?
All children should receive hepatitis A vaccine at age 1 year (i.e., 12–23 months). Vaccination should be completed according to the licensed schedules and integrated into the routine childhood vaccination schedule. Children who are not vaccinated by age 2 years can be vaccinated at subsequent visits. States, counties, and communities with existing hepatitis A vaccination programs for children aged 2–18 years are encouraged to maintain these programs. In these areas, new efforts focused on routine vaccination of children aged 1 year should enhance, not replace, ongoing programs directed at a broader population of children. In areas without existing hepatitis A vaccination programs, catch-up vaccination of unvaccinated children aged 2–18 years can be considered. Such programs might especially be warranted in the context of increasing incidence or ongoing outbreaks among children or adolescents. (8/10/06) -
Can Twinrix be interchanged with hepatitis A and hepatitis B vaccines if the person is started on the single-antigen vaccines and then switched to Twinrix and vice versa?
Because the hepatitis B component of Twinrix is equivalent to a standard adult dose of hepatitis B vaccine, the schedule is the same whether Twinrix or single-antigen hepatitis B vaccine is used.Single-antigen hepatitis A vaccine may be used to complete a series begun with Twinrix and vice versa. A person who receives one dose of Twinrix may complete the hepatitis A series with two doses of adult formulation hepatitis A vaccine separated by at least 5 months. A person who receives two doses of Twinrix may complete the hepatitis A series with one dose of adult formulation hepatitis A vaccine or Twinrix 5 months after the second dose. A person who begins the hepatitis A series with a dose of single-antigen hepatitis A vaccine may complete the series with two doses of Twinrix. (8/10/06)
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Why was the age requirement for hepatitis A lowered to one year of age?
The age was lowered to one year based on safety and efficacy data presented by the vaccine manufacturers to the FDA. (8/10/06) -
If a child is older than 2 years of age and has received one dose of hepatitis A vaccine, does ACIP recommend the 2nd dose of vaccine?
Yes. For long-term protection the person should complete the series with the second dose. (8/10/06)
Schedule
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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, www.immunize.org/catg.d/2081ab.pdf (exit). (6/26/03)
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Content last reviewed on November 6, 2007
Content Source: National Center for Immunization and Respiratory Diseases