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A Look at Each Vaccine: Hepatitis B Vaccine

The hepatitis B vaccine is given to prevent the severe liver disease that can develop when children or adults are infected with hepatitis B virus. The hepatitis B vaccine is given as a series of three shots. The first dose is given between birth and 2 months of age. The second dose is given one to two months after the first dose, and the third dose is given between 6 months and 18 months of age.

Are hepatitis B virus infections easily avoided?

Large quantities of hepatitis B virus are present in the blood of people with hepatitis B; in fact, as many as one billion infectious viruses can be found in a milliliter (one-fifth of a teaspoon) of blood from an infected individual. Therefore, hepatitis B virus is transmitted in the blood of infected individuals during activities that could result in exposure to blood, such as intravenous drug use, tattooing, or sex with people who are infected. However, it is also possible to catch hepatitis B virus through more casual contact, such as sharing washcloths, toothbrushes or razors. In each of these cases, unseen amounts of blood can contain enough viral particles to cause infection. In addition, because many people who are infected don't know that they are infected, it is very hard to avoid the chance of getting infected with hepatitis B virus.

What is hepatitis B virus?

Hepatitis B virus attacks the liver. Hepatitis B virus infections are known as the "silent epidemic" because many infected people don't experience symptoms until decades later when they develop hepatitis (inflammation of the liver), cirrhosis (severe liver disease), or cancer of the liver (hepatocellular carcinoma). Every year in the United States about 3,000 people die from hepatitis soon after they are infected, and another 10,000 go on to develop long-term hepatitis, putting them at high-risk for cirrhosis and liver cancer.

How do you catch hepatitis B virus?

Blood from a person infected with hepatitis B virus is heavily contaminated with the virus. As a result, contact with blood is the most likely way to catch hepatitis B. Even casual contact with the blood of someone who is infected (sharing of washcloths, toothbrushes, or razors) can cause infection.

Healthcare workers are at high risk of catching the disease, as are intravenous drug users and newborns of mothers infected with the virus. Sexual contact can also expose people to infection. The virus is also present in low levels in saliva.

Because the disease can be transmitted by casual contact, and because about 1 million people are infected with hepatitis B virus (many of whom don't know that they have it), it has been hard to control hepatitis B virus infections in the United States. The original strategy (started in the early 1980s) was to vaccinate only those at highest risk (for example, healthcare workers, patients on dialysis, and intravenous drug users). But because the disease can be transmitted to those who are not in high-risk groups, this vaccine strategy didn't work. The incidence of hepatitis B virus disease in the United States was unchanged 10 years after the vaccine was first used! For this reason, the vaccine strategy changed. Now all infants and young children are recommended to receive the hepatitis B vaccine and the incidence of hepatitis B virus infections in the United States is starting to decline. If we stick with this strategy, we have a chance to finally eliminate this devastating disease within one or two generations.

A vaccine to prevent cancer

Because hepatitis B virus can cause liver cancer, the hepatitis B vaccine prevents cancer. It is one of two vaccines that can prevent cancer. The other vaccine is the human papillomavirus (HPV) vaccine.

How is the hepatitis B vaccine made?

People are protected against hepatitis B virus infection by making an immune response to a protein that sits on the surface of the virus. When hepatitis B virus grows in the liver, an excess amount of this surface protein is made. The hepatitis B vaccine is made by taking the part of the virus that makes surface protein ("surface protein gene") and putting it into yeast cells. The yeast cells then produce many copies of the protein which are subsequently used to make the vaccine. When the surface protein is given to children in the vaccine, their immune systems make an immune response which provides protection against infection with the hepatitis B virus.

The first hepatitis B vaccine was made in the 1980s by taking blood from people infected with hepatitis B virus and separating or purifying the surface protein from the infectious virus. Because blood was used, there was a risk of contaminating the vaccine with other viruses that might be found in blood, such as HIV. Although contamination with HIV was a theoretical risk of the early, blood-derived, hepatitis B vaccine, no one ever got HIV from the hepatitis B vaccine. That is because the blood used to make vaccine was submitted to a series of chemical and physical treatments that inactivated any possible contaminating virus. Today, there is no risk of contaminating the vaccine with other viruses because the surface protein is manufactured in the laboratory.

Does the hepatitis B vaccine have side effects?

Some children will develop pain or soreness in the local area of the shot, and low-grade fever.

There is one extremely rare, but serious, side effect: 1 out of every 600,000 doses of the hepatitis B vaccine will cause a severe allergic reaction, called anaphylaxis, with symptoms including swelling of the mouth, difficulty breathing, low blood pressure or shock. Anaphylaxis usually occurs within 15 minutes of receiving the vaccine. Although anaphylaxis can be treated, it is quite frightening. People should remain at the doctor’s office for about 15 minutes after getting the vaccine.

Although the hepatitis B vaccine is made in yeast cells, no one has ever been shown to be allergic to the yeast proteins contained in the hepatitis B vaccine (see Yeast Allergies).

Why should I vaccinate my newborn child if I know that I am not infected with hepatitis B virus?

Before the hepatitis B vaccine, every year in the United States about 18,000 children were infected with hepatitis B virus by the time they were 10 years old. This statistic is especially important because people are much more likely to develop liver cancer or cirrhosis if they are infected early in life, rather than later in life (most people are infected with hepatitis B virus when they are adolescents and young adults).

About 9,000 of the 18,000 children infected in the first 10 years of life caught the virus from their mother during birth. However, many young children didn't catch the disease from their mother. They caught it from either another family member or someone else who came in contact with the child. Because hepatitis B can be transmitted by relatively casual contact with items contaminated with blood of an infected person, and because many people who are infected with hepatitis B virus don't know that they have it, it is virtually impossible to be "careful enough" to avoid this infection.

For these reasons, all young children are recommended to receive the hepatitis B vaccine. The best time to receive the first dose is right after birth. This will ensure that the child will be protected as early as possible from catching the disease from someone that doesn't know that he/she is infected with the virus.

Should teenagers and adults get the hepatitis B vaccine?

The hepatitis B vaccine should be given to all teenagers and adults who have not yet received the hepatitis B vaccine or been infected by hepatitis B virus.

Do the benefits of the hepatitis B vaccine outweigh its risks?

Every year in the United States about 3,000 people die soon after catching hepatitis B virus. In addition, every year about 10,000 people become chronically infected, putting them at high risk of developing the long-term consequences of hepatitis B virus infection: cirrhosis and liver cancer. In fact, with the exception of influenza virus, hepatitis B virus causes more severe disease and death in the United States than any other vaccine-preventable disease. On the other hand, the hepatitis B vaccine is an extremely rare cause of a severe allergic reaction called anaphylaxis. To date, no one has died from this reaction, but it is theoretically possible that this could occur.

Because hepatitis B virus is a common cause of severe disease and death in the United States, and the hepatitis B vaccine does not cause permanent damage or death, the benefits of the hepatitis B vaccine clearly outweigh its risks.

All newborns and infants
Anyone who has not previously received the hepatitis B vaccine
Disease Risks Vaccine Risks
  • Hepatitis (inflammation of the liver)
  • Cirrhosis (severe liver disease)
  • Cancer of the liver (hepatocellular carcinoma)
  • Disease can be fatal
  • Pain or soreness at the injection site
  • Low-grade fever
  • Severe allergic reaction (1 of 600,000 doses)


Plotkin SA, Orenstein W, and Offit PA. Hepatitis B Vaccines in Vaccines, 6th Edition. 2012, 205-234.

Reviewed by: Paul A. Offit, MD
Date: April 2013

Materials in this section are updated as new information becomes available. The Vaccine Education Center staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family's personal health. You should not use it to replace any relationship with a physician or other qualified healthcare professional. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult your physician or, in serious cases, seek immediate assistance from emergency personnel.


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