Hepatitis A vaccine

Examples

This vaccine is given as a shot (injection) most often into the upper arm (deltoid) muscle.

How It Works

In response to the vaccine, which contains an inactive form of hepatitis A virus (HAV), the body makes antibodies against HAV. This response is known as active immunity.

Why It Is Used

Immunization with hepatitis A vaccine is recommended for all children beginning at 1 year of age. Two separate doses are given at least 6 months apart.¹

The Centers for Disease Control and Prevention made this recommendation in early 2006. Many young children and adolescents have not had the hepatitis A vaccine.

Immunization is also recommended for children and adolescents who have not had the hepatitis A vaccine and who are in the following situations:

• A community outbreak of the disease has recently occurred.
• They live in a state or community that has set up routine vaccination because the disease occurs there more often than in other areas.

In general, the hepatitis A vaccine is also recommended for people whose travel, job, medical condition, or lifestyle puts them at risk of exposure to the virus. This includes:²

• People who will travel to a foreign country where sanitary conditions are poor and hepatitis A is common. Plan for vaccination 6 months before travel, if possible. If not, vaccination at least 1 month before travel offers some protection, and 2 weeks before travel may also be effective³.
• People who have anal contact with a sex partner.
• People who work with monkeys that are infected with HAV and those who work with HAV in a research setting.
• People who have long-term (chronic) liver disease.
• People who have blood-clotting disorders, such as hemophilia, and must receive clotting factors from human donors.
• People who are awaiting or who have had a liver transplant.

Routine vaccination of hospital workers, food handlers, and child care center workers and attendees is not recommended at this time because their risk of infection generally is no greater than that of the wider community. If outbreaks of HAV infection do occur in those settings, people who were exposed to the virus should receive a shot of immune globulin (IG).⁴

The hepatitis A vaccine also may be given to someone after being exposed to the hepatitis A virus. The vaccine can prevent hepatitis A infection when given within 2 weeks of the exposure.⁵

The hepatitis A vaccine is believed to prevent HAV infection for at least 20 years.⁶

How Well It Works

Hepatitis A vaccine is 94% to 100% effective in preventing HAV infection when both shots in the vaccination series are given.⁷

The vaccine offers some protection within 2 weeks after the first dose.⁸ But to have long-term protection, adults and children need to have a second dose 6 to 18 months later (depending on the recommendation of the vaccine manufacturer).

Side Effects

Although the hepatitis A vaccine contains components derived from human blood or plasma, there is no risk of exposure to blood-borne diseases.

The vaccine is safe and effective for people 1 year of age or older who have no known allergies to the contents of the vaccine.

Reactions to the vaccine are mild and usually do not last for more than 24 hours. The most common side effects include:

• Soreness, redness, and swelling at the injection site.
• Headache.
• Tiredness, fever, and feeling sick to your stomach (nausea).

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

The vaccine provides some protection against hepatitis A virus (HAV) infection after the first shot.⁵ If you are exposed to the virus within 2 weeks of getting the first shot, you may also receive a dose of IG. The vaccine can be given safely with IG without altering the effectiveness of either. IG should be injected into a different site on the arm.

People who are allergic to the vaccine should receive IG if they will be at risk of exposure to the hepatitis A virus.

A combination vaccine (Twinrix) that protects against both hepatitis A and hepatitis B also is available.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

References

Citations

1. Centers for Disease Control and Prevention (2008). Recommended immunization schedules for persons aged 0–18 years—United States, 2008. MMWR, 57(01): Q1–Q4. Also available online: http://www.cdc.gov/mmwr/pdf/wk/mm5701-immunization.pdf. [Erratum in MMWR, 57(12): 319. Also available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5712a6.htm.]
2. Centers for Disease Control and Prevention (2006). Hepatitis A vaccine: What you need to know. Vaccine Information Statement. Department of Health and Human Services, National Immunization Program (3/21/06). Available online: www.cdc.gov/vaccines/pubs/vis/downloads/vis-hep-a.pdf.
3. Bell BP, et al. (2005). Hepatitis A virus. In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 6th edition, vol. 2, pp. 2162–2185. Philadelphia: Elsevier.
4. Centers for Disease Control and Prevention (2006). Prevention of hepatitis A through active or passive immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 55 (RR-7): 1–23. Also available online: http://www.cdc.gov/mmwr/PDF/rr/rr5507.pdf.
5. Centers for Disease Control and Prevention (2007). 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, 56(RR-41): 1080–1084. Also available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5641a3.htm.
6. Craig AS, Schaffner W (2004). Prevention of hepatitis A with the hepatitis A vaccine. New England Journal of Medicine, 350(5): 476–481.
7. American Academy of Pediatrics (2006). Hepatitis A. In LK Pickering et al., eds., Red Book: 2006 Report of the Committee on Infectious Diseases, 27th ed., pp. 326–335. Elk Grove Village, IL: American Academy of Pediatrics.
8. Victor JC, et al. (2007). Hepatitis A vaccine versus immune globulin for postexposure prophylaxis. New England Journal of Medicine, 357(17): 1685–1694.