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.
- The disease
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. Indeed, the new vaccine strategy has virtually eliminated the disease in children less than 19 years of age. If we stick with this strategy, we have a chance to finally eliminate this devastating disease within one or two generations.
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.
Facts about hepatitis B
- Two billion people, or one in three, have been infected with hepatitis B worldwide. Of these, more than 350 million live with chronic hepatitis B.
- One in 20 people living in the United States has been infected with hepatitis B, and up to 2 million of these are chronically infected putting them at increased risk of developing cirrhosis and liver cancer.
- Each year about 620,000 people die from hepatitis B worldwide, and 5,000 of these deaths occur in the United States.
- Hepatitis B is transmitted through blood and is 100 times more infectious than HIV; an estimated one billion infectious viruses are in one-fifth of a teaspoon of blood of an infected person, so exposure to even a minute amount, such as on a shared toothbrush can cause infection.
- Hepatitis B is sometimes referred to as the “silent epidemic” because most people who are infected do not experience any symptoms.
- Liver cancer caused by hepatitis B is the fifth most common cause of cancer deaths in males throughout the world and the eighth in women.
- The World Health Organization (WHO) recommends the inclusion of hepatitis B vaccine be in immunization programs of all countries; in 2011, 179 countries (of 193) had infant immunization programs.
- The 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 that 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 that 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 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 (Vaccine Ingredients – Yeast).
- Other questions you might have
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 hepatitis B from people who don’t know that they are 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 with hepatitis B virus.
Is it okay to get an extra dose of hepatitis B vaccine?
Yes. Although extra doses of vaccine are not recommended, you can think of the extra dose as another chance for the immune system to “see” the hepatitis B virus. A vaccine is not the only time the immune system will “see” the virus or bacteria contained in it. People may be exposed to the virus or bacteria at school or the store or when visiting family or friends. An extra dose of vaccine is like one more exposure, except the difference is that the virus or bacteria in any vaccine has been made safe, so it won’t make you ill.
I am a healthcare worker who did not develop hepatitis B antibodies after immunization. What should I do?
Not everyone responds to the hepatitis B vaccine. In fact, in a group of adults younger than 40 years of age who have received two doses of the vaccine only 75 of 100 will be protected. Following the third dose, this number will increase to 90 of 100. However, people older than 40 years of age will be less likely to respond to the vaccine with increasing age.
Even if a person does not respond to three doses, it does not mean that he or she is at high risk for hepatitis B. Because hepatitis B is transmitted primarily through blood and body fluids, using safety precautions while working will help decrease the chance of exposure to the disease. It is also possible that the immune response was not great enough to be measured by the laboratory test, but would still provide some level of protection upon exposure to hepatitis B. The CDC recommends getting the three-dose series again if an immune response is not generated following the first series.
About 10 of every 100 adults do not respond to the third dose of the hepatitis B vaccine and so will be reliant on those around them being immune to hepatitis B as an indirect form of protection. In other words, these people will be reliant on herd immunity.
- Relative risks and benefits
Do the benefits of the hepatitis B vaccine outweigh its risks?
Every year in the United States about 3,000 people die following an overwhelming hepatitis B virus infection. 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 because the hepatitis B vaccine does not cause permanent damage or death, the benefits of the hepatitis B vaccine clearly outweigh its 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.