Disease Questions & Answers
What causes hepatitis A?
Hepatitis A is caused by hepatitis A virus (HAV).
How does HAV spread?
HAV is found in the fecal material (stool or bowel movement) of people with HAV infection. The virus is
spread when an infected person's fecal material gets into the mouth of another person. This can happen in
a variety of ways, for example, when an infected person who prepares or handles food doesn't wash his or
her hands adequately after using the toilet and then touches other people's food. A person can also be
infected by drinking water contaminated with HAV or drinking beverages chilled with contaminated ice.
Contaminated food, water, and ice can be significant sources of infection for travelers to many areas of the
world. HAV can also be passed by close personal contact with an infected person, including living with an
infected person or having sexual contact with an infected person.
Can HAV be spread through sex contact?
Yes, particularly when a sex partner has contact with an infected person's anus.
How long does it take to show signs of illness after coming in close contact with a person who has HAV
It can take 15-50 days to become infected, with an average of 28 days.
What are the symptoms of hepatitis A?
People with symptoms of hepatitis A can feel quite sick. Symptoms might include fever, loss of appetite,
nausea, stomach pain, dark urine, and yellowing of the skin and whites of the eyes. The illness often starts
suddenly and symptoms can last up to two months, but some people (about 15%) can have symptoms lasting
up to 12 months. Adults who have symptoms require hospitalization in 11-22% of cases and are absent from
work an average of 27 days.
The likelihood of developing symptoms of hepatitis A is related to one's age. Most of the time, children less
than six years of age have no symptoms but most adults (approximately 70%) do have symptoms.
How serious is hepatitis A?
Hepatitis A can be quite serious. Each year in the United States, approximately 100 people die from HAV-related causes.
Can people become chronically infected with HAV?
No. HAV only causes acute infections, not chronic disease. (Both hepatitis B and hepatitis C viruses can
cause chronic infection.)
How common is hepatitis A in the United States?
CDC estimates that 61,000 new infections occurred in 2003 (this includes people with and without
Certain areas of the United States have had higher-than-average rates of hepatitis A, and it is recommended
that children who live in these areas receive routine hepatitis A vaccination. (See "Hepatitis A Vaccine"
How common is hepatitis A in the world?
Hepatitis A occurs widely throughout the world. The disease is especially common in countries in Latin
America, Africa, the Middle East, Asia, the Caribbean, and the Western Pacific. This means that people can
become infected with HAV in many travel destinations, even when using luxury tourist accommodations.
The only destinations around the world for which CDC does not recommend hepatitis A vaccination or
immune globulin for U.S. travelers before departure are Canada, Western Europe, Australia, New Zealand,
How does a person know if s/he is infected with HAV?
Only a blood test can tell for sure. The symptoms of hepatitis A are the same as symptoms of other types
of viral hepatitis. There is also a blood test that shows if a person was infected with HAV in the past.
Is there a medicine to treat hepatitis A?
There is no medicine that will treat or "cure" hepatitis A. Supportive care includes bed rest, fluids, and fever-reducing medicines.
How long can a person with HAV infection spread the disease?
The most likely time for an infected person to spread HAV to others is two weeks before the infected
person develops symptoms. Clearly, if a person doesn't even know that s/he is infected, it makes it
difficult to protect others from getting the disease. The risk of spreading the disease becomes smaller
over time and can still be present one week or longer after symptoms develop (e.g., yellowing of skin and
If a person has had close personal contact with an HAV-infected person and hasn't been vaccinated,
what should the person do?
If an unvaccinated person thinks that s/he might have been exposed, s/he should call their health professional
immediately to schedule an appointment to determine whether a real exposure has occurred and whether
administration of immune globulin is necessary. Immune globulin is a concentrated dose of human
antibodies that includes hepatitis A antibody. This preparation can protect an exposed person from
developing HAV infection. It's important to give the dose of immune globulin within two weeks following
exposure (the closer to the exposure the better). (See Q & A about "Hepatitis A Vaccine" for information
about immune globulin.)
Can a person get infected with HAV more than once?
No. Once a person has had HAV infection, s/he is immune to the disease and will not become infected with
How does HAV differ from hepatitis B and hepatitis C viruses?
Hepatitis A, B, and C are all viruses that attack and injure the liver, and all can cause similar symptoms.
Usually people get HAV infection from close personal contact with an infected person. Hepatitis B and C
viruses are spread when an infected person's blood or body fluids enters another person's bloodstream.
Hepatitis B and C virus infections can cause lifelong liver problems. Hepatitis A will not. There are
vaccines that will protect people from hepatitis A and hepatitis B. At this time, no vaccine protects people
from hepatitis C. If a person has had one type of viral hepatitis in the past, it is still possible to get the other
Technically reviewed by the Centers for Disease
Control and Prevention, August 2005
Hepatitis A Vaccine Questions & Answers
When did the first hepatitis A vaccine first become available?
In 1995. There are currently two hepatitis A vaccine products commercially available in the United States.
They are equally safe and effective.
What kind of vaccine is hepatitis A vaccine?
Hepatitis A vaccine is an inactivated virus vaccine. No part of the vaccine is "live."
How is hepatitis A vaccine given?
The vaccine is given by an injection into the muscle of the upper arm.
Who should get this vaccine?
People at increased risk for exposure to HAV infection or those who are more likely to get seriously ill if
infected with HAV should be vaccinated. According to CDC
recommendations, these individuals include
- People age 12 months or older
who are traveling to or working in any area of the world
except the United States, Canada, Western Europe, Japan, New Zealand, and Australia
- Men who have sex with men
- Illegal drug users, both oral and injecting
- People who have blood clotting disorders
- People who work with HAV-infected primates (monkeys and apes, for example). This is
the only group of workers shown by statistics to be at increased risk for HAV infection.
- People with chronic liver disease (People with liver disease are not at increased risk of
getting infected but are at risk for developing serious complications if they get infected.)
- People who work with HAV-infected primates
(monkeys and apes, for example). Note: This is the only group of workers shown
by statistics to be at increased risk for HAV infection. Hepatitis A vaccine
is NOT routinely recommended for healthcare workers, sewage workers, or
Hepatitis A vaccination is also recommended for all children two years of age and older in
states or communities where CDC reported a high average annual rate of HAV infection
during the years 1987-1997. These states include Alaska, Arizona, California, Idaho,
Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Utah, and Washington. In
addition, many communities have similarly high rates of HAV infection. All children two years of age and older in these places also should be routinely vaccinated against
CDC has determined that other states in the United States had a moderate average annual
rate of hepatitis A disease during 1987-1997. CDC recommends that routine hepatitis A
vaccination should be considered for children
two years of age and older who live in these
states. These states include Arkansas, Colorado, Missouri, Montana, Texas, and Wyoming.
CDC also recommends that hepatitis A vaccination should be considered for children who
live in large or small communities with moderate rates of hepatitis A infection.
In addition, any person who
wishes to be immune to hepatitis A is recommended for vaccination.
How many doses of hepatitis A vaccine are recommended for fullest protection?
Two doses are recommended. The second dose is given no sooner than six months after the
Iím not in a group for which
hepatitis A vaccine is recommended. Can I still get vaccinated to protect myself
against HAV-contaminated food, etc.?
Yes. Hepatitis A vaccine is safe and effective and is licensed for anyone age 12
months and older.
For how long does hepatitis A
vaccine protect you?
Although data on long-term protection are limited, estimates suggest that
protection will last for at least 20 years.
What organizations recommend hepatitis A vaccine?
The Centers for Disease Control and Prevention (CDC), the American Academy of
Pediatrics (AAP), and the American Academy of Family Physicians (AAFP) all recommend
this vaccine for certain individuals.
Is hepatitis A vaccine safe?
This vaccine is very safe. Since 1995, no
serious adverse events have been definitively linked to the
vaccine. The risk of hepatitis A vaccine causing serious harm or death is extremely small.
What side effects have been reported with this vaccine?
The most common side effect is a sore arm, which happens to one out of two adults and one
out of five children. Less common side effects include headache, loss of appetite, low-grade
fever, or tiredness. When these problems happen, they usually start 3-5 days after
vaccination and usually last for one or twodays. A very rare but serious side effect is a
generalized allergic reaction. If this happened, it typically would occur within a few
minutes to a few hours following the injection.
How effective is hepatitis A vaccine?
Hepatitis A vaccine is very effective. It appears that 100% of adults, adolescents, and
children become immune to HAV infection after getting two doses. After one dose, at least
94% of people become immune for the short term, for example, before travel to high-risk
Who should not receive hepatitis A vaccine?
People who have had a serious allergic reaction to hepatitis A vaccine in the past, or who
are known to be allergic to any part of the hepatitis A vaccine, should not receive it. People
with moderate or severe acute illness should wait to receive hepatitis A vaccine until their
condition has improved.
Can I receive hepatitis A vaccine when I am pregnant?
The safety of hepatitis A vaccination during pregnancy has not been determined;
however, because hepatitis A vaccine is produced from inactivated HAV, the theoretical
risk to the developing fetus is expected to be low. The risk associated with vaccination
should be weighed against the risk for hepatitis A in women who might be at high risk
for exposure to HAV.
Can the vaccine cause HAV infection?
Is there a vaccine that protects against both hepatitis A and hepatitis B?
Yes. Twinrix, the hepatitis A and B combination vaccine manufactured by
GlaxoSmithKline, was licensed for use in the United States in 2001 for people 18 years of
age and older. Three doses of Twinrix are necessary for full protection against both
hepatitis A and hepatitis B.
How soon are persons protected
after receiving hepatitis A vaccine?
Protection against hepatitis A begins four weeks after the first dose of
hepatitis A vaccine.
If risk of infection (e.g.,
travel) starts sooner than 4 weeks after the first vaccine dose, what should be
Because protection might not be optimal until 4 weeks after vaccination, persons
traveling to a high-risk area less than 4 weeks after the initial dose of
hepatitis A vaccine should also be given an injection of immune globulin.
What is immune globulin?
Immune globulin is a preparation of antibodies that can be given before exposure
for short-term protection against hepatitis A and to persons who have already
been exposed to hepatitis A virus. Immune globulin must be given within 2 weeks
after exposure to hepatitis A virus for maximum protection.
What should be done for
travelers who are younger than age 12 months to protect them from HAV infection?
Immune globulin is recommended for travelers younger than age 12 months because
the vaccine is not licensed for use in this age group.
Can hepatitis A vaccine be
given after exposure to hepatitis A virus?
Hepatitis A vaccine is not licensed for use after exposure to hepatitis A virus.
In this situation, immune globulin should be used. However, giving hepatitis A
vaccine at this time will provide protection for the future.
Should pre-vaccination testing
be done before getting the vaccine?
Pre-vaccination testing is done only in specific instances to control cost
(e.g., with persons who were likely to have had hepatitis A in the past). Your
healthcare provider can advise you whether this would be helpful in your
Technically reviewed by the Centers for Disease
Control and Prevention, August 2005