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A Look at Each Vaccine: Hepatitis A Vaccine

The hepatitis A vaccine is given to people who are traveling to parts of the world where hepatitis A virus infections are common. The hepatitis A vaccine is also now recommended for all children living in the United States.

The hepatitis A vaccine should be given as a series of two shots — the second administered six to 12 months after the first. Children receiving the first shot should be at least 1 year old.

The threat of hepatitis A virus

Although the threat of hepatitis A virus infection is very common in developing countries, the United States is not, by any means, hepatitis A virus-free. Each year, about 7,000 people in the United States, many of whom are children, contract hepatitis A virus. And every year about 50 people die from hepatitis A virus infection. As a result, the Centers for Disease Control and Prevention (CDC) has now recommended that all children between 12 and 23 months of age should get the hepatitis A virus vaccine.

What is hepatitis A virus?

Hepatitis A is a virus that causes hepatitis (inflammation of the liver). Symptoms include fever, jaundice (a yellowing of the skin), nausea and vomiting. Young children are much less likely to develop symptoms when they are infected with hepatitis A virus than adults.

Are infections caused by hepatitis A virus similar to those caused by hepatitis B virus?

Although hepatitis A virus sounds like it would be similar to hepatitis B virus, the viral infections are really quite different. Hepatitis B virus can cause long-term problems, such as cirrhosis (chronic liver damage) and liver cancer. On the other hand, hepatitis A virus doesn't cause long-term problems. Also hepatitis B virus kills about 750 people every year whereas hepatitis A virus kills about 50 people every year. Finally, whereas hepatitis B virus is transmitted solely by coming in contact with someone else who is infected, hepatitis A virus is also transmitted in contaminated food or water.

How do you catch hepatitis A virus?

People infected with hepatitis A virus excrete the virus in their stools. You can catch the virus in a number of ways.

• Babies with hepatitis A virus will have diapers that are contaminated with the virus. Adults changing these diapers are likely to get infected with the virus if they don't carefully wash their hands with soap and water after handling the diaper.
• Because hepatitis A virus is present in the stools of people who are infected, countries or cities with low standards for the handling and disposal of sewage have an enormous problem with hepatitis A virus infections. The problem is that the virus quickly enters the water supply and contaminates anything that comes in contact with the water. It is probably not unrealistic to think about many developing countries as having a thin layer of hepatitis A virus that covers anything that you could put into your mouth.

How can you avoid catching hepatitis A virus when traveling?

Anyone traveling to countries where hepatitis A virus infections are common should avoid the following:

• Ice and unbottled water
• Uncooked shellfish
• Uncooked or unpeeled vegetables and fruit
• Food from street vendors
• Salads

How is the hepatitis A vaccine made?

The hepatitis A vaccine is made by taking whole hepatitis A virus and killing it with the chemical formaldehyde. Because the virus is inactivated, it cannot possibly cause hepatitis (see How Are Vaccines Made?).

Does the hepatitis A vaccine have side effects?

The hepatitis A vaccine can cause pain, redness and tenderness where the shot was given. The vaccine can also cause headache in about 5 percent of recipients. The hepatitis A vaccine has now been given to millions of people without serious side effects.

Who should get the hepatitis A vaccine?

The hepatitis A vaccine should be given to two general groups of people:

• Travelers to countries that have a high incidence of hepatitis A infections such as Asia, Central America, South America, the Mediterranean Basin, the Middle East, Southern Europe, the Caribbean and Mexico.
• All children living in the United States are now recommended to get the Hepatitis A vaccine.
• All household contacts of international adoptees. Those traveling to get the child should be immunized about two weeks before departure.
• Anyone who wants to avoid infection with hepatitis A.

How long should I wait after getting the hepatitis A vaccine before I travel?

The hepatitis A vaccine is most effective if given at least four weeks before traveling. But the vaccine is still somewhat effective if given at least two weeks before traveling. If you are going to travel within two weeks of receiving the vaccine, it is probably better to get a shot of something called "immune serum globulin." This is a preparation of antibodies that also contains antibodies directed against hepatitis A virus. You don't develop long-lived protection by giving "immune serum globulin," but at least it will get you through your trip. Protection afforded by immune serum globulin lasts several months.

Do the benefits of the hepatitis A vaccine outweigh the risks?

Hepatitis A virus infections are very common throughout the world. So common, in fact, that it is really easier to list the countries where you are unlikely to catch the infection than countries where you are likely to catch the infection. Also the United States still has about 7,000 cases of hepatitis A virus infections every year. Although hepatitis A virus infections do not cause long-term liver damage, still about 50 people die every year from severe, overwhelming infection with hepatitis A virus. Because the vaccine does not have serious side effects, the benefits of the vaccine clearly outweigh its risks.

Reviewed by: Paul A. Offit, MD
Date: March 2009