Hepatitis B: The Disease & Vaccines
Many people think of hepatitis B as a disease spread through sex and injection drug use. This causes some to question the need for a birth dose of hepatitis B vaccine. The reality is more complex. Yes, hepatitis B virus is most often spread through sexual contact and injection drug use, particularly from sharing needles. But each year, people are infected in other ways. Often, they do not even know they were exposed to hepatitis B virus. This is especially true for children who often do not have symptoms when they are infected with hepatitis B. People can live for decades with chronic hepatitis B infection and only to later develop liver disease or liver cancer. During the years between infection and diagnosis, they can unknowingly spread the virus to others. This combination of many people not knowing they have hepatitis B and subsequent spread to others is why hepatitis B infections are known as the “silent epidemic.”
The disease
What is hepatitis B virus?
Hepatitis B virus attacks the liver. People often don't have symptoms until decades later when they develop:
- Hepatitis — inflammation of the liver
- Cirrhosis — severe liver disease
- Liver cancer — known as hepatocellular carcinoma
Every year in the U.S., about 22,000 people are infected with hepatitis B, and about 2,000 people die from their infections.
How do you catch hepatitis B virus?
People most often get hepatitis B from contact with blood. Blood from a person infected with hepatitis B virus is heavily contaminated with the virus. The virus is present at such high levels that it can be spread by contact with quantities of blood too small to see. The virus can also survive on surfaces longer than most viruses — up to seven days. As a result, even casual contact with the blood of someone who is infected can cause infection. Casual contact can include sharing of washcloths, toothbrushes, or razors. The virus can also spread among team members, particularly for contact sports where exposure to blood is more common. People have also been occasionally known to get hepatitis B from contaminated tattooing and medical equipment.
People more likely to come into contact with the blood of infected individuals are at increased risk for hepatitis B. This includes healthcare workers, intravenous drug users and newborns of mothers infected with the virus. People can also be infected through sexual contact. The virus is present in semen and vaginal fluids. Hepatitis B virus can be found in low levels in saliva, but it is not thought to spread by saliva. The virus is also not spread through air, food or water.
The spread of hepatitis B virus has been difficult to control in the U.S. because the disease can be transmitted by casual contact and because so many chronically infected people don’t know they are infected. It’s estimated that about three-quarters of a million to 2 million people in the U.S. are chronically infected with hepatitis B virus. The original strategy aimed at controlling hepatitis B in the U.S. started in the early 1980s. The goal at that time 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 U.S. remained unchanged 10 years after the strategy was first used! So, the vaccine strategy was changed. Starting in 1991, all infants and young children were recommended to receive the hepatitis B vaccine. As a result, the incidence of hepatitis B virus infections in the U.S. started to decline. Indeed, this strategy has virtually eliminated the disease in children less than 19 years of age. If we stick with it, we have a chance to finally eliminate this devastating disease within one or two generations.
For a more detailed look at hepatitis B vaccine recommendations over time, check the “My baby isn’t that baby: The argument against hepatitis B vaccine at birth” section of the July 2025 Parents PACK article, “9,000 Reasons for Routine Childhood Hepatitis B Vaccination.”
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 of blood from an infected individual. A milliliter is about one-fifth of a teaspoon. Therefore, amounts of blood too small to be seen can contain enough viral particles to cause infection. In addition, many people don't know that they are infected. For these reasons, it is very hard to avoid the chance of getting infected with hepatitis B virus.
Facts about hepatitis B
- About 260 million people live with chronic hepatitis B. This means about 1 of every 32 people throughout the world are living with a chronic hepatitis B infection.
- In 2022, 1.1 million people died from hepatitis B worldwide. About 2,000 deaths from hepatitis B occur each year in the U.S.
- Hepatitis B is 100 times more infectious than HIV.
- Globally in 2022, only about 1 of every 10 people with chronic hepatitis B infections were aware of their infection, and only 3 of 100 were being treated for their infection. The U.S. estimates that about 1 in 2 people in this country don’t know they are infected with hepatitis B. Liver cancer accounts for about 5% of cancer deaths in the U.S.
- Almost half of liver cancers are caused by chronic infection with hepatitis B.
- The World Health Organization (WHO) recommends hepatitis B vaccine for all infants. More than 8 of 10 infants born throughout the world receive three doses of hepatitis B vaccine.
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 reproduces itself 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 the surface protein ("surface protein gene") and putting it into yeast cells. The yeast cells then produce many copies of the protein, which is purified and used as the vaccine. When a person is vaccinated, their immune system makes an immune response that provides protection against infection with the hepatitis B virus.
The first hepatitis B vaccine was made in the 1980s. That vaccine was made by taking blood from people infected with hepatitis B virus and purifying the surface protein from the blood. Using blood to make the vaccine meant there was a risk that other viruses could contaminate the vaccine. This included HIV, which was only discovered in the late 1980s. Although contamination with HIV was a theoretical risk of the early, blood-derived hepatitis B vaccine, no one ever got HIV from this early version of the hepatitis B vaccine. That is because the blood used to make the vaccine was treated with several chemicals to kill any possible contaminating viruses. Today, there is no risk of contaminating the vaccine with other viruses because the surface protein is made in the lab.
Who should get the hepatitis B vaccine?
The hepatitis B vaccine is given to prevent the severe liver disease that can develop when people are infected with hepatitis B virus. The hepatitis B vaccine is given to infants as a series of three shots. The first dose is given within 24 hours of birth. 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 vaccine is also recommended for those up to 60 years of age who have not previously received it and those 60 years and older who are at increased risk or who simply want to be protected against hepatitis B virus.
Does the hepatitis B vaccine have side effects?
Some children will develop pain or soreness in the area where the shot was given. Some will also get a low-grade fever.
There is one extremely rare, but serious, side effect. About 1 out of every 600,000 doses of the hepatitis B vaccine will cause a severe allergic reaction, called anaphylaxis. When this happens, a person can have swelling in the mouth, difficulty breathing, low blood pressure or shock. Anaphylaxis usually occurs within 15 minutes of receiving the vaccine. Anaphylaxis can be treated, but it is quite frightening. People should stay at the facility where they got vaccinated for about 15-30 minutes in case of any allergic reactions.
The hepatitis B vaccine is made in yeast cells, but 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?
Every year in the U.S. before the hepatitis B vaccine was given routinely to infants about 18,000 children would be infected with hepatitis B virus by the age of 10 years. Two things make infections in children concerning. First, young children often do not have symptoms when they get hepatitis B, so many don’t know they are infected. Second, people are much more likely to develop liver cancer or cirrhosis if they are infected early in life.
About 9,000 of the 18,000 children infected in the first 10 years of life got the virus from their mother during birth. However, many young children didn't get the disease from their mother. They got it from either another family member or someone else who came in contact with the child. It is virtually impossible to be “careful enough” to avoid hepatitis B for two reasons:
- Hepatitis B can be transmitted by relatively casual contact with items containing the blood of an infected person.
- Many infected people don't know that they have hepatitis B.
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 quickly as possible since many people don’t know that they are infected with the virus.
Listen to Dr. Offit explain why newborns get the hepatitis B vaccine by watching this short video, part of the series Talking About Vaccines with Dr. Paul Offit.
Find a more detailed discussion in the July 2025 Parents PACK article, “9,000 Reasons for Routine Childhood Hepatitis B Vaccination.”
Should teenagers and adults get the hepatitis B vaccine?
The hepatitis B vaccine should be given to all teenagers and adults up to 60 years of age who have not yet received it. Adults 60 years and older should get the vaccine if they are at high risk for infection or if they would like to be protected against this virus.
Is it OK to get an extra dose of hepatitis B vaccine?
Yes. Extra doses of vaccine are not recommended, but they are not generally harmful. You can think of the extra dose as another chance for your immune system to “see” 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 pathogens at school or the store or when visiting family or friends. An extra dose of vaccine is like one more exposure.
I am a healthcare worker who did not develop hepatitis B antibodies after immunization. What should I do?
Two versions of hepatitis B vaccine are available. One, called Heplisav-B, contains a novel adjuvant that was not present in previous versions of hepatitis B vaccine used by adults (Engerix-B and Recombivax HB). Some people did not respond to the older version hepatitis B vaccines. In fact, in a group of adults younger than 40 years of age who got two doses of the older version vaccine 75 of 100 were protected. Following the third dose, this number increased to 90 of 100. However, people older than 40 years of age were less likely to respond to the vaccine with increasing age. On the other hand, 90 to 100 of 100 adults 18 years of age and older respond to Heplisav-B, which was approved for use in 2018.
Even if people do not respond to three doses, it does not mean that they lack immunity to hepatitis B It is 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.
People who did not have measurable immunity after getting the hepatitis B vaccine are recommended to get a second hepatitis B vaccine series. If they had the older three-dose versions and did not respond, they may be eligible to get Heplisav-B, which is a two-dose vaccine. If you are not sure, talk to your doctor about what approach makes the most sense for your situation.
About 5 to10 of every 100 children and adults younger than 40 years of age do not respond after three doses of the hepatitis B vaccine. Some of these people will be recommended to get vaccinated again. About 5 of 100 people will still not respond after getting all recommended doses of both series. Note that children younger than 18 years of age cannot get Heplisav-B.
People who do not respond to vaccination after getting the vaccine series twice will need to take precautions to reduce their chance of exposure. They will also need to rely on those around them for protection.
Can hepatitis B be eradicated?
Eradication means an infectious disease has been eliminated from around the world. No cases are occurring anywhere. Only one infectious disease of people has been eradicated: smallpox.
To be eradicated, a virus must only infect people. Hepatitis B virus has types that can infect other animals, and the type that infects people can infect other animals. For this reason, hepatitis B might never be eradicated.
Hepatitis B virus could potentially be eliminated though. Elimination in public health terms means that the virus could be removed from a particular geographic area. For example, the U.S. has eliminated measles, polio and rubella. Elimination would take time though because many adults live with chronic hepatitis B. To eliminate this virus, we would need to vaccinate children as they were born, so they don’t get infected. As those children became adults, fewer people would have chronic infections, and the population would become increasingly free of hepatitis B.
Are there treatments for hepatitis B?
Most people recover from a hepatitis B infection without treatment. For those who become chronically infected, they may be able to take some antiviral medicines. But a few notes about this. First, current antiviral medications often require long or ongoing treatment. Second, they can help prolong life by limiting liver damage or development of liver cancer, but they don’t cure the infection. New types of medications are in clinical trials, so hopefully in the future the options for these patients will improve.
When babies are born to women with hepatitis B, they are usually treated right after birth. For babies, this means getting vaccinated and receiving immunoglobulins, which are antibodies. But if a woman has high levels of the virus in her blood, the baby may still get infected. So, when the woman’s hepatitis B status is known before delivery, she may be treated with antiviral medications to decrease the virus in her blood before delivery.
Relative risks and benefits
Do the benefits of the hepatitis B vaccine outweigh its risks?
About 2,000 people die each year in the U.S. from overwhelming hepatitis B virus infections. In addition, about 22,000 people are infected with hepatitis B each year. Some of them will remain chronically infected, putting them at high risk for the long-term consequences of hepatitis B virus infection: cirrhosis and liver cancer. In fact, with the exception of influenza and COVID-19 viruses, hepatitis B virus causes more severe disease and death in the U.S. than any other vaccine-preventable disease.
On the other hand, the hepatitis B vaccine is safe. On rare occasions, it can cause a severe allergic reaction, called anaphylaxis. No one has died from this reaction, but it is theoretically possible that this could occur without appropriate medical care.
Because hepatitis B virus is a common cause of severe disease and death in the U.S. and because the hepatitis B vaccine does not cause permanent damage or death, the benefits of the hepatitis B vaccine clearly outweigh its risks.
Disease risks
- Hepatitis (inflammation of the liver)
- Cirrhosis (severe liver disease)
- Cancer of the liver (hepatocellular carcinoma)
- Disease can be fatal
Vaccine risks
- Pain or soreness at the injection site
- Low-grade fever
- Severe allergic reaction (1 of 600,000 doses)
References
Books
Orenstein WA, Offit PA, Edwards KM, and Plotkin SA. Hepatitis B Vaccines in Plotkin’s Vaccines, 8th Edition. 2018, 389-432.
Reviewed by Paul A. Offit, MD, on Aug. 14, 2025