Questions & Answers

What kind of vaccine is hepatitis A vaccine?
Hepatitis A vaccine is an inactivated virus vaccine. No part of the vaccine is "live."

How is hepatitis A vaccine administered?
The vaccine is given by an injection into the muscle of the upper arm for adults and older children and in the thigh muscle of toddlers.

Who should get this vaccine?
Many people are recommended to receive hepatitis A vaccine, including people at increased risk for exposure to hepatitis A virus infection and people who are more likely to get seriously ill if infected with the virus. According to CDC recommendations, people who should be vaccinated include:

• All children starting at age 1 year (12–23 months)
• People age 12 months or older who are traveling to or working in an area of the world except the United States, Canada, Western Europe, Japan, New Zealand, and Australia
• Men who have sex with men
• Users of illicit drugs, injectable or noninjectable
• People who anticipate having close personal contact with an international adoptee from a country of high or intermediate endemicity during the first 60 days following the adoptee's arrival in the United States
• People who have blood clotting disorders
• People who work with HAV-infected primates or with hepatitis A virus in a research laboratory setting (no other groups have been shown to be at increased risk for HAV infection because of occupational exposure)
• People with chronic liver disease
• Any person who wishes to be protected from hepatitis A virus infection

Hepatitis A vaccine is not routinely recommended for healthcare workers, sewage workers, or daycare providers. Children who are not vaccinated by age two years should be vaccinated as soon as possible.

How many doses of hepatitis A vaccine are recommended for full protection?
Two doses are recommended. The second dose is given no sooner than six months after the first dose.

I'm not in a group for which hepatitis A vaccine is recommended. Can I still get vaccinated to protect myself against infection?
Yes. Hepatitis A vaccine is safe and effective and is licensed for use in any person age 12 months and older. Any person who wishes to be immune to infection with hepatitis A virus is recommended to receive the vaccine.

How long does hepatitis A vaccine protect you?
Estimates for long-term protection for fully vaccinated people (i.e., full two-dose series) suggest that protection from hepatitis A virus infection could last for at least 25 years in adults and at least 14–20 years in children. Experts continue to study the long-term effectiveness of this vaccine to determine whether a booster dose will be needed.

What organizations recommend hepatitis A vaccine?
The Centers for Disease Control and Prevention, the American Academy of Pediatrics, the American Academy of Family Physicians, the American College of Obstetricians and Gynecologists, and the American College of Physicians recommend the vaccine.

Is hepatitis A vaccine safe?
Yes, hepatitis A vaccine is very safe. No serious adverse events have been attributed definitively to hepatitis A vaccine. Since the licensure of the first hepatitis A vaccine in 1995, millions of doses of hepatitis A vaccine have been distributed and administered worldwide as well as in the United States.

What side effects have been reported with this vaccine?
The most common side effect is a sore arm, which happens to one out of two adults and one out of five children. Less common side effects include headache, loss of appetite, low-grade fever, or tiredness. When these problems happen, they usually start 3–5 days after vaccination and usually last for one or two days. A very rare but serious side effect is a generalized allergic reaction. If this happens, it typically occurs within a few minutes to a few hours following the injection.

How effective is hepatitis A vaccine?
Hepatitis A vaccine is very effective. It appears that all adults, adolescents, and children become immune to hepatitis A virus infection after getting two doses. After one dose, at least 94 out of 100 people become immune for the short term. It is very important to get the full two-dose series!

Who should not receive hepatitis A vaccine?
People who have had a serious allergic reaction to hepatitis A vaccine in the past, or who are known to be allergic to any part of the hepatitis A vaccine, should not receive it. People with moderate or severe acute illness should wait to receive hepatitis A vaccine until their condition has improved.

Can I receive hepatitis A vaccine when I am pregnant?
The answer to this question is not well studied, but because hepatitis A vaccine is produced from inactivated hepatitis A virus, the theoretical risk to the developing fetus is expected to be low. The risk associated with vaccination, however, should be weighed against the risk for hepatitis A in women who may be at high risk for exposure to hepatitis A virus.

Can the vaccine cause hepatitis A infection?
No.

Is there a vaccine that protects against both hepatitis A and hepatitis B virus infections?
Yes. Twinrix, the hepatitis A and hepatitis B combination vaccine manufactured by GlaxoSmithKline, was licensed for use in the United States in 2001 for people 18 years of age and older. Three doses of Twinrix are necessary for full protection against hepatitis A and hepatitis B virus infections.

What is immune globulin (IG)?
IG is a preparation of antibodies that can be given before exposure to hepatitis A virus for short-term protection against hepatitis A infection and to people who have already been exposed to hepatitis A virus. IG must be given within 2 weeks after exposure to the virus for maximum protection.

What are the recommendations for the use of IG and/or hepatitis A vaccine prior to travel?
All susceptible people (individuals who have never had the infection or the vaccine) traveling to or working in countries except the United States, Canada, Western Europe, Japan, New Zealand and Australia should receive hepatitis A vaccine or IG before departure. (If traveling to the Caribbean, people should consider getting hepatitis A vaccine or IG if travel is to areas of questionable sanitation.)

For unvaccinated people ages 1 through 40 years, the first dose of hepatitis A vaccine should be administered as soon as travel is considered, actually any time prior to travel. The second dose should be given at least 6 months after the first dose. For the best protection, individuals who are over age 40, immunocompromised people (e.g., people with HIV infection), and people with chronic liver disease or other chronic medical conditions planning to travel in 2 weeks or less should receive the initial dose of hepatitis A vaccine and IG at the same time. The second dose of the 2-dose hepatitis A vaccine series should be given no sooner than six months after the first dose. This second dose is needed to ensure long-lasting protection. Travelers who choose not to get the hepatitis A vaccine, who are less than 12 months old, or who are allergic to the vaccine should be given IG only. The dosage of IG depends on how long you plan to travel and how much you weigh.

What should be done for travelers who are younger than age 12 months to protect them from infection with hepatitis A virus?
Recommendations have not changed for this age group as noted in the previous question. IG is recommended for travelers younger than age 12 months because hepatitis A vaccine is not licensed for use in this age group.

Can hepatitis A vaccine be given after exposure to hepatitis A virus?
Yes. The recommendations for the use of hepatitis A vaccine after exposure to hepatitis A virus have changed. People who recently have been exposed to hepatitis A and who previously have not had hepatitis A vaccine should be given a single dose of hepatitis A vaccine or IG as soon as possible. Hepatitis A vaccine is preferred for healthy people age 12 months through 40 years of age. For people over 40 years of age, IG is preferred, but hepatitis A vaccine can be used if IG is unavailable. IG should be given to children younger than 12 months of age, immunocompromised people, people who have diagnosed chronic liver disease, and people for whom vaccine is contraindicated.
 

Questions and answers about hepatitis A disease

Technical content reviewed by the Centers for Disease Control and Prevention, March 2011