Disease Questions & Answers
What causes hepatitis B?
Hepatitis B is caused by the hepatitis B virus (HBV).
How does HBV spread?
HBV is spread by either skin puncture or mucous membrane contact with the blood
or other body fluids of an HBV-infected person. The highest concentrations of
the virus occur in blood and wound secretions. Moderate concentrations of HBV
are found in semen and vaginal fluid. HBV is not spread by air, food, or water.
In the United States, the primary routes of HBV
transmission are through sex contact, from an infected mother to her baby during
birth (perinatal), and by percutaneous (through the skin) exposures (e.g.,
injecting illegal drugs with a contaminated needle).
HBV is efficiently transmitted by sex contact and
it is estimated that sexual transmission accounts for about 50% of new
infections among adults in the United States. The most common risk factors for
sexual transmission among heterosexuals include having multiple sexual partners,
a history of a sexually transmitted disease, or sex with a known infected
person. Men who have sex with men are also at high risk of HBV transmission.
Perinatal transmission from HBV-infected mothers
to their infants results from exposures to maternal blood and body fluids at the
time of delivery. Breastfeeding has not been associated with transmission of HBV.
HBV transmission during childhood can also occur.
Most early childhood transmission occurs in households of persons with chronic
HBV infection, but transmission has also been documented in daycare centers and
in schools. The most likely mechanisms of early childhood transmission involve
contact between an infected person’s body fluids (e.g., their blood or
secretions from their wounds or skin lesions) and breaks in a child’s skin or
mucous membranes (e.g., imperceptible punctures in the child’s skin or mucous
membranes). HBV also can spread through bites, as a consequence of pre-chewing
food for infants, and through contact with the virus from sharing personal items
such as razors or toothbrushes. HBV remains infectious for at least seven days
outside the body and can be found on objects, even in the absence of visible
The risk of HBV infection from HBV-contaminated
needlesticks is 50–100 times higher than the risk of HIV transmission. In the
United States, injecting illegal drugs accounts for approximately 15% of new HBV
infections. Other types of percutaneous (through the skin) exposures, including
tattooing and body piercing, have been reported to result in HBV transmission in the United States when good infection control practices have
not been used. Unsafe injections in medical settings are a major source of HBV
transmission in many developing countries and might be a risk for U.S. residents
How long does it take to show signs of
hepatitis B after being exposed?
The incubation period ranges from six weeks to six months.
What are the symptoms of hepatitis B?
At least 50% of adults with acute hepatitis B show no symptoms. Children under
five years of age who become infected rarely show any symptoms. Persons with an
acute case of hepatitis B might suffer from nausea, lack of appetite, tiredness,
pains in the muscles, joints, or stomach, fever, diarrhea or vomiting, headache,
dark urine, light-colored stools, and yellowing of the skin and whites of the
How serious is hepatitis B?
Hepatitis B is very serious. People who have symptoms with acute hepatitis B
generally feel quite ill and might need to be hospitalized. Approximately
200–300 Americans die of fulminant (overwhelming new infection) hepatitis B
every year. While 90%–95% of adults eventually recover from an acute HBV
infection, a feeling of tiredness and poor health might last for months. In
addition, about 90% of infants, 30%–60% of young children, and 5% of adults who
are infected with HBV are unable to clear the infection from their bodies and
become chronically infected with the virus. This serious consequence is
What does it mean to have chronic HBV
Persons with chronic (lifelong) HBV infection are infectious and can
transmit HBV to others. Usually chronically infected people do not feel sick and do not realize
they are infected. They are also at high risk of developing chronic liver
disease, including cirrhosis (scarring of the liver), liver failure, and liver
What are the complications of chronic HBV
An estimated 15%-25% of persons with chronic HBV infection eventually
develop serious liver disease. Chronic HBV infection is responsible for most HBV-related sickness and death, including cirrhosis, liver failure,
and liver cancer. When persons are infected at a young age, these
forms of liver disease do not appear usually until middle age.
How serious a problem is chronic HBV infection
in the world?
In the United States, an estimated 3,000–4,000 persons die each year of HBV-related
cirrhosis, and another 1,000-1,500 die each year of HBV-related liver cancer.
Worldwide, the medical consequences of chronic HBV infection are a huge problem.
Approximately 350 million persons around the world are chronically infected with
HBV and approximately 1 million of these persons die each year from liver failure or
What is the risk of getting
HBV infection while traveling in other countries?
The risk of HBV infection for international travelers is generally low, except
for certain travelers in countries where the prevalence of chronic HBV is high
or intermediate. These areas of the world include Asia, Sub-Saharan Africa,
Amazon Basin, Eastern Europe, and the Middle East. Ask your healthcare
professional if you should be vaccinated before traveling to one of these areas.
How common is hepatitis B in the United
About 5% of the U.S. population has been infected with HBV at some time in the
past. Of these, about 1.25 million persons have chronic HBV infection and most
of these persons do not know they are infected.
The number of new cases of hepatitis B in the
United States has been decreasing recently, both because of increased
vaccination against the disease and because of changes in risk-reduction
behaviors among at-risk populations in response to the HIV/AIDS epidemic. In the
mid-1980s, there were 26,000 cases reported; in 2003, there were 7,526 cases
reported. However, reported cases of hepatitis B represent only a small
proportion of all persons infected with the virus; many have no symptoms of
disease, and many with disease are not reported to health department officials.
Based on studies that have looked for evidence of infection in people’s blood,
it is estimated that nearly 73,000 persons became infected with HBV in 2003 in
the United States.
How do you know if you have HBV infection?
Hepatitis B can only be diagnosed by blood testing.
The blood tests can tell whether or not a person is currently infected and whether or not a
person has been infected in the past. If the test indicates a person has been
infected in the past, testing will also determine whether the person has
developed protective antibodies to the virus (meaning they have gotten over the
disease and are now immune) or whether they still have virus in their blood,
indicating they might have chronic HBV infection.
Is there a treatment for hepatitis B?
There are several
FDA-approved medications that may help a person who has chronic HBV infection.
Not everyone is a candidate for these medications. Researchers continue to seek
additional cures for hepatitis B.
There is no treatment for people with a newly acquired case of hepatitis B.
How long is a person with hepatitis B
A person with acute or chronic hepatitis B is contagious as long as they
have the virus in their blood, which can only be determined by blood testing. People can be infected for their entire lives.
People who know they are infected with HBV should
be careful to avoid infecting others. Family members and sex contacts of
infected persons should be vaccinated against hepatitis B as soon as possible. Sex contacts should be tested after they’ve been
vaccinated to be sure they are immune, or protected, by the vaccine series.
Infected persons should not donate blood and should not share toothbrushes,
razors, or other personal care articles with others. Infected mothers (or family
members) should not chew food for infants.
HBV is not spread by sneezing, hugging, coughing,
food, or water, sharing eating utensils or drinking glasses, or casual contact.
Persons with chronic HBV infection should not be excluded from work, school,
play, childcare, or other settings.
What should you do if you have been exposed to
Contact your doctor or clinic. If an unvaccinated person is exposed to blood or
another body fluid known to be HBV infected, it is recommended that they receive
treatment with HBIG (a blood product containing protective antibodies to the
virus) and also the first dose of hepatitis B vaccine as soon as possible.
Following this, they will need additional doses of hepatitis B vaccine.
Can you get hepatitis B more than once?
No; if you get an acute case of hepatitis B and recover you should have
antibodies in your blood that will protect you from any further infection with
How does hepatitis B differ from hepatitis A
Hepatitis A, B, and C are all viruses that attack and injure the liver, and all
can cause similar symptoms. Hepatitis A virus
transmitted through fecal material (stool or bowel movement). Usually, a person can get hepatitis A from close
personal contact (e.g., sex contact, sharing a household) with an infected
person. Although it is less common, a person can also become infected by eating
or drinking food or water contaminated with hepatitis A virus. Hepatitis A does not cause lifelong liver problems.
Hepatitis C, formerly known as hepatitis non-A
non-B, is a blood-borne virus that is spread in much the same way as hepatitis
B. Hepatitis C can cause lifelong liver problems,
including liver failure and liver cancer. There are several licensed treatments
available for those infected with the hepatitis C virus: not everyone is a
candidate for these medications.
Although there are vaccines to prevent hepatitis
A and B, there is no vaccine for hepatitis C. If you've had hepatitis A or C in
the past, it is still possible to get hepatitis B.
Technically reviewed by the Centers for Disease
Control and Prevention, August 2005
Hepatitis B Vaccine Questions & Answers
When did hepatitis B vaccine become available?
The first hepatitis B vaccine became commercially available in the United
States in 1982. In 1986, a hepatitis B vaccine produced by "recombinant DNA
technology" was licensed, and a second recombinant-type hepatitis B vaccine was
licensed in 1989.
These two recombinant vaccines are the ones
currently used in the United States, although the original plasma-derived
vaccine is also safe and effective and is still used elsewhere in the world. The
two recombinant vaccines are produced by different manufacturers but can be
interchanged for use during an individual's vaccine series.
What kind of vaccine is it?
The hepatitis B vaccines used in the United States are a recombinant DNA vaccine,
which means it is produced by inserting the gene for HBV into common baker's
yeast where it is grown, harvested, and purified. HBV infection cannot occur
from receiving hepatitis B vaccine.
How is this vaccine given?
It is recommended that the hepatitis B vaccine be given in the deltoid muscle
for children and adults and the thigh for infants.
Who should get this vaccine?
Hepatitis B vaccine, usually a three-dose series, is recommended for all infants
beginning at birth.
All older children who did not get all doses of hepatitis B vaccine as an infant
should complete their series as soon as practical. Most states require hepatitis
B vaccine for school entry. Adolescents who are just starting their series will
need two or three doses, depending on their age and the brand of vaccine used.
Adults at increased risk of acquiring HBV infection should also be vaccinated.
What groups of adults are at increased risk of HBV infection?
Adults who are at increased risk of HBV infection include
- Health care workers or others with occupational exposure to blood or blood
- Men who have sex with men
- Persons with more than one sex partner in a six-month period
- Persons diagnosed recently with a sexually transmitted disease (STD)
- Injection drug users
- Inmates of long-term correctional facilities
- Hemodialysis patients and patients with early renal failure before they require hemodialysis
- Recipients of certain blood products (e.g., hemophiliacs)
- Staff and residents of institutions or group homes for the developmentally
- Household members and sex partners of persons with chronic HBV infection
- Susceptible (non-infected) persons from U.S. populations known to previously or
currently have high rates of childhood HBV infection, including Alaska Natives,
Pacific Islanders, and immigrants or refugees from countries with intermediate
or high levels of chronic HBV infection.
- International travelers who will live or work for six or more months in areas
with intermediate or high levels of chronic HBV infection
Who recommends this vaccine?
The Centers for Disease Control and Prevention (CDC), the American Academy of
Pediatrics (AAP), the American Academy of Family Physicians (AAFP), and the
American College of Physicians (ACP) all recommend this vaccine.
How safe is this vaccine?
Hepatitis B vaccine is very safe. Globally, more than one billion hepatitis B
vaccine doses have been administered. In the United States, more than 30 million
adults and 40 million infants and children have received this vaccine. The
majority of children who receive this vaccine have no side effects. Serious
reactions are rare.
What side effects have been reported with this vaccine?
Of those children experiencing a side effect, most will have only a very mild
reaction such as soreness at the injection site (3%–9%) or low-grade fever.
Adults are slightly more likely to experience such mild symptoms. Serious
allergic reactions following hepatitis B vaccination are rare.
How effective is this vaccine?
After three properly administered doses of vaccine, at least 90% of healthy
young adults and more than 95% of infants, children, and adolescents develop
protective antibodies and subsequent immunity to HBV infection.
Why is this vaccine recommended for all babies when most of them won't be
exposed to HBV for many years, if then?
There are three basic reasons for recommending that all infants receive
hepatitis B vaccine. First, babies and young children have a very high risk for
developing chronic HBV infection if they become infected at a young age. Most of the serious
consequences of HBV infection (i.e., liver cancer and cirrhosis) occur among
persons with chronic HBV infection and persons with
chronic HBV infection are most likely to spread the
infection to others.
Second, early childhood infection occurs. About 16,000 children under 10 years
of age were infected with HBV every year in the United States before routine
infant hepatitis B vaccination was recommended. Although these infections
represented only 5%-10% of all HBV infections in the United States, it is
estimated that 18% of persons with chronic HBV infection in the United States
acquired their infection during early childhood. Many of these childhood
infections occur among infants born to mothers who are not HBV-infected.
Most early childhood transmission occurs in households where a person has
chronic HBV infection, but transmission has also been recognized in daycare
centers and schools. The most probable ways children become infected with HBV
are from skin puncture (e.g., biting) or from having their mucous membranes or
cuts and scratches come in contact with infectious body fluids from an infected
person. HBV remains infectious for at least seven days outside the body and can
be found on and transmitted through sharing of inanimate objects such as
washcloths or toothbrushes.
Third, long-term protection following infant vaccination is expected to last for
decades and will ultimately protect against acquiring
infection at any age.
Why should your child be protected against hepatitis B if h/she won't ever
inject drugs or be sexually promiscuous?
HBV can be transmitted in many ways in addition to sex contact and injecting
drug use. On the average, any baby born in the United States has a 5% chance of
acquiring HBV infection during his or her lifetime. By avoiding obvious means of
exposure, people can reduce their odds of becoming infected. But while there are
degrees of risk involved in contracting HBV infection, there is no such thing as
Cases of Hepatitis B Virus Transmission" for
examples of HBV transmissions in a variety of settings.
Will your child need a booster shot later in life?
At the present time, booster doses are not routinely recommended for persons
with normal immune systems. Although the level of protective antibodies in the
blood of a vaccinated person seems to decline with time, the immune system
retains an immunization “memory” and if the person is exposed to HBV, the system
“kicks in” and provides the needed protection.
Experts are continuing to monitor the long-term effectiveness of hepatitis B
vaccine and will issue recommendations on the need for booster doses if evidence
shows they are necessary.
Should I be tested before I get the vaccine to see if I'm already infected or
Blood testing before vaccination is not recommended for the routine vaccination
of infants and children.
Testing should be considered for individuals who have a high risk of having been
exposed to the virus in the past, including men who have sex with men, injection
drug users, family members of persons with chronic HBV infection, and persons
from countries or ethnic groups where hepatitis B is common.
If a person is already infected with HBV or is immune to hepatitis B, getting
the vaccine will neither help nor harm them. The main reason for testing persons
at higher risk for HBV is to determine if they are infected. If they are, they
must be referred to a health professional for ongoing medical care for chronic
Should I get my blood tested after getting the vaccine series to make sure it
Routine testing after vaccination is not recommended for infants, children,
adolescents, or most adults.
Testing to verify a person's immunity is recommended for certain individuals:
infants born to HBV-infected mothers, dialysis patients and other persons with
compromised immune systems, health care workers who have contact with blood, and
sex contacts of persons with chronic HBV infection.
What should be done if a person gets the first two doses of hepatitis B vaccine
but never gets back for the third dose. Should the series be restarted?
No. There is no need to start the vaccine series over just because the interval
between doses is longer than recommended.
Who should NOT receive hepatitis B vaccine?
People who had a serious allergic reaction to one dose of hepatitis B vaccine
should not have another. Persons with a moderate or severe acute illness should
postpone receiving the vaccine until their condition is improved.
Can I get this vaccine when I am pregnant?
I’m an adult who wants
hepatitis B vaccination. How can I pay for the shots?
If you have insurance, the cost of hepatitis B vaccination may be covered. If
not, sometimes these shots are available at low cost through special programs or
from health departments. Call your local health department for details.
Will hepatitis B vaccination
protect me from hepatitis A or hepatitis C?
No. Hepatitis A and hepatitis C are different diseases caused by different
viruses. There is a vaccine for hepatitis A, but there is no vaccine for
hepatitis C at this time. For information on hepatitis A and hepatitis C, talk
to your healthcare professional or call your local health department.
Technically reviewed by the Centers for Disease
Control and Prevention, August 2005