What causes hepas A?
Hepas A is an infecous liver disease caused by
hepas A virus (HAV).
How does hepas A virus spread?
Hepas A virus is spread from person to person
by pung something in the mouth that has been
contaminated with the stool (feces, poop) of a person
infected with hepas A virus. This type of spread
is called “fecal-oral.” This can happen in a variety of
ways, such as when an infected person who prepares
or handles food doesn’t wash his or her hands
adequately aer using the toilet and then touches
other people’s food. A person can also be infected
by drinking water contaminated with hepas A
virus or drinking beverages chilled with virus
contaminated ice. Contaminated food, water, and
ice can be signicant sources of infecon for travelers
to many areas of the world. For this reason, the virus
is more easily spread in areas where there are poor
sanitary condions or where good personal hygiene
is not observed.
Most hepas A viral infecons in the United States
result from internaonal travel to countries with
intermediate or high rates of hepas A virus infecon,
contact with a household member or sex partner
who has hepas A, or sharing street drugs. Casual
contact, as in the oce, factory, or school seng,
does not spread the virus.
Can hepas A virus be spread through sex?
Yes. Sex involves close, inmate contact (vaginal,
anal, or oral sex) and increases the risk of exposure
to hepas A virus in the feces of an infected person.
What are the symptoms of hepas A?
Not everyone infected with hepas A virus will
have symptoms; however, some infected people can
feel quite sick. If symptoms are present, they usually
occur suddenly and can include fever, redness, loss
of appete, nausea, abdominal discomfort, voming,
joint pain, clay-colored stools, dark urine, and
jaundice (yellowing of the skin and eyes).
How long does it take to show signs of illness
aer coming in close contact with a person
who has hepas A virus infecon?
It can take 15–50 days to develop symptoms (average
28 days). People with hepas A virus infecon
might not have any signs or symptoms of the infecon.
Adults are more likely to have symptoms than children.
About 7 out of 10 adults have symptoms, while
children younger than age 6 years usually have no
symptoms. About 1 out of 8 people with symptoms
will have a prolonged or relapsing infecous illness
that lasts up to 6 months.
How long do symptoms last?
Symptoms usually last less than 2 months; however,
a few people are ill for as long as 6 months.
How serious is hepas A?
Hepas A can be quite serious. While most people
fully recover within 2–3 months, older people, those
with chronic liver disease or other health problems
may develop severe illness. A mul-state hepas A
outbreak that began in 2016 in the United States has
primarily involved people who use drugs, people who
were homeless, and their close contacts. As of July
2020, more than 33,300 cases had been reported, of
whom 61% had been hospitalized and about 1% died.
Can people become chronically (life-long)
infected with hepas A virus?
No. Hepas A leads to a short-term infecon, limited
to a few weeks or months, not a chronic infecon.
Relapsing hepas A, as described above, goes away
and is NOT a chronic infecon. Both hepas B and
hepas C viruses can cause chronic infecon.
How common is hepas A in the United
States?
The incidence of hepas A in the U.S. increased
more than 10-fold from 2015 to 2019, with over
18,800 cases reported to CDC in 2019. The number
of reported cases declined by half to 9,952 in 2020.
Hepatitis A: Quesons and Answers
i n f o r m at i o n a b o u t t h e d i s e a s e a n d vacc i n e s
c on t i n u e d o n t h e n e x t p a g e
FOR PROFESSIONALS www.immunize.org / FOR THE PUBLIC www.vaccineinformation.org
www.immunize.org/catg.d/p4204.pdf
Item #P4204 (9/11/2023)
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This number is an underesmate of the actual
number of infecons: CDC esmates that about
19,900 cases actually occurred in 2020. In recent
years, large outbreaks have occurred among people
experiencing homelessness, people who use drugs,
and men who have sex with men. A smaller number
of cases are associated with internaonal travel or
eang imported food contaminated with HAV.
How common is hepas A virus infecon
throughout the world?
Hepas A occurs throughout the world. It is
especially common in countries in Lan America,
Africa, the Middle East, Asia, the Caribbean, and the
Western Pacic. This means that people can become
infected with the virus in many travel desnaons,
even when using luxury tourist accommodaons.
The only desnaons around the world for which
CDC does not recommend hepas A vaccinaon
or immune globulin (IG) for U.S. travelers before
departure are Canada, Australia, New Zealand, Japan,
and parts of Western Europe.
How does a person know if he or she is
infected with hepas A virus?
To diagnose acute hepas A, a blood test called
“IgM class anbody to hepas A virus” (IgM
an-HAV) is needed. There is also a blood test
available that shows if an unvaccinated person was
infected with hepas A virus in the past (total
hepas A anbody, also called an-HAV). Talk to
your doctor or your local health department if you
suspect that you have been exposed to the virus or
any other type of hepas virus.
Is there a treatment for hepas A?
No. There is no specic treatment for hepas A.
Supporve care includes bed rest, uids, and
fever-reducing medicines. Take fever-reducing
medicine only if your physician recommends it.
How long can a person with hepas A virus
infecon spread the virus?
The most likely me for an infected person to spread
hepas A virus to others is during the 2 weeks
before the infected person develops symptoms (e.g.,
yellowing of skin and eyes). The risk of spreading
hepas A virus becomes lower over me and can
sll be present 1 week or longer aer symptoms
develop. Infants are more likely to spread hepas A
virus for longer periods of me.
If an unvaccinated person has had close
personal contact with a person who is
infected with hepas A virus, what should
the person do?
If an unvaccinated person thinks that he or she might
have been exposed to hepas A virus, the person
should call their healthcare provider immediately to
determine what to do. Vaccine or IG may be needed.
IG is a concentrated dose of human anbodies that
includes an-HAV. In most cases, either of these
preparaons can protect an exposed person from
developing hepas A virus infecon. It’s important
to give vaccine and/or IG within 2 weeks following an
exposure (the sooner, the beer) to prevent infecon
caused by the exposure. Vaccinaon provides long-
lasng protecon and should be done unless vaccine
is contraindicated. IG alone is used for children
younger than age 1 year or people who either refuse
or cannot be vaccinated. IG may be given, in addion
to vaccine, based upon a healthcare provider’s
evaluaon of people over 40, people who are immuno-
compromised, and people with chronic liver disease.
Can a person be infected with hepas A virus
more than once?
No. Once a person recovers from the infecon, he or
she develops life-long protecon from future infecon.
How does hepas A virus dier from
hepas B virus (HBV) and hepas C
virus (HCV)?
• Hepas A, B, and C are three dierent viruses
that injure the liver and cause similar symptoms in
people with acute (recently acquired) disease.
• Hepas A virus is spread by geng infected fecal
maer into a person’s mouth who has never had
hepas A virus infecon (e.g., through unwashed
hands or sexual contact). Hepas B and hepas
C viruses are spread when an infected person’s
blood or blood-contaminated body uids enter
another person’s bloodstream.
Hepas A: Quesons and Answers (connued) page 2 of 5
c on t i n u e d o n t h e n e x t p a g e
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Hepas A: Quesons and Answers (connued) page 3 of 5
• Hepas B and hepas C virus infecons can
cause chronic liver problems. Infecon with
hepas A virus does not.
• There are vaccines that will protect people from
infecon with hepas A and hepas B. Currently,
there is no vaccine to protect people from hepas
C virus infecon.
• There are medicaons that are approved by the
Food and Drug Administraon (FDA) to treat
chronic hepas B and chronic hepas C viral
infecons. There is no specic treatment for
hepas A virus infecon. (See the queson “Is
there treatment for hepas A?”)
• If a person has had one type of viral hepas in the
past, it is sll possible to get the other types.
What kind of vaccine is hepas A vaccine?
Hepas A vaccine is an inacvated (killed) virus
vaccine.
How is hepas A vaccine administered?
The vaccine is given by an injecon into the muscle of
the upper arm for adults and older children and in the
thigh muscle of toddlers and younger children.
Who should get this vaccine?
Many people are recommended to receive hepas A
vaccine, including people at increased risk for
exposure to hepas A virus infecon and people
who are more likely to get seriously ill if infected
with the virus. According to CDC recommendaons,
people who should be vaccinated include:
• All children starng at age 1 year (12–23 months)
• All children age 2 through 18 years not previously
vaccinated
• All people infected with HIV
• People age 6 months or older who are traveling to
or working in an area of the world except the United
States, Canada, Japan, New Zealand, Australia, and
parts of Western Europe. Vaccine given to a child
age 6–11 months does not count toward the 2-dose
series given aer the rst birthday.
• Men who have sex with men
• Users of illicit drugs, injectable or non-injectable
• People who are homeless or in temporary housing,
such as a shelter
• People who ancipate having close personal
contact with an internaonal adoptee from a
country of high or intermediate levels of hepas A
virus infecon during the rst 60 days following the
adoptee’s arrival in the United States
• People who work with HAV-infected primates or
with hepas A virus in a research laboratory seng
• People with any kind of chronic liver disease,
including infecon with hepas B or hepas C
viruses, cirrhosis, fay liver disease, alcoholic liver
disease, autoimmune hepas, or liver enzyme
tests (ALT or AST) persistently more than twice
normal levels.
• Any person who wishes to be protected from
hepas A virus infecon
Hepas A vaccine is not rounely recommended for
healthcare personnel, sewage workers, or day-care
providers. Children who are not vaccinated by age 2
years should be vaccinated as soon as possible.
ACIP now recommends roune hepas A
vaccinaon for people who are homeless.
Can you provide a denion of “homeless”?
CDC denes a homeless person as one who 1) las
housing, 2) is without permanent housing but may
ay in a shelter or transional housing, or 3) “doubles
up” with a series of friends or extended family
members. It can also include people previously
homeless who are being released from a prison
or hospital if they do not have a able housing
situaon. The key to the denion is the inability
of the person’s living arrangement.
How many doses of hepas A vaccine are
recommended?
Two doses are recommended. The second dose is
given no sooner than 6 months aer the rst dose.
I’m not in a group for which hepas A vaccine
is recommended. Can I sll get vaccinated to
protect myself against infecon?
Yes. Hepas A vaccine is safe and eecve. Any
person who wishes to be immune to infecon with
hepas A virus can receive the vaccine.
c on t i n u e d o n t h e n e x t p a g e
www.immunize.org/catg.d/p4204.pdf / Item #P4204 (9/11/2023)
Hepas A: Quesons and Answers (connued) page 4 of 5
How long does hepas A vaccine protect you?
Esmates for long-term protecon for fully vaccinated
people (i.e., two-dose series) suggest that protecon
from hepas A virus infecon could last for at least
25 years in adults and at least 14–20 years in children.
Protecon aer the rst dose has been shown to
last more than a decade. Protecon may be life-long,
similar to the immunity that follows natural infecon,
but experts connue to evaluate the long-term
eecveness of this vaccine.
What organizaons recommend hepas A
vaccine?
The Centers for Disease Control and Prevenon, the
American Academy of Pediatrics, the American
Academy of Family Physicians, the American College
of Obstetricians and Gynecologists, and the American
College of Physicians, recommend this vaccine.
Is hepas A vaccine safe?
Yes, hepas A vaccine is very safe. Since the
licensure of the rst hepas A vaccine in 1995,
millions of doses of hepas A vaccine have been
administered worldwide, as well as in the United
States. No serious adverse events have been
aributed to the vaccine.
What side eects have been reported with
this vaccine?
The most common side eect is a sore arm, which
happens to one out of two adults and one out of ve
children. Less common side eects include headache,
loss of appete, low-grade fever, or redness. When
these problems happen, they usually start 3–5 days
aer vaccinaon and usually last for 1–2 days. A
very rare but serious side eect is a severe allergic
reacon. If this happens, it typically occurs within a
few minutes to a few hours aer the injecon.
(See the queson on “Who should not receive
hepas A vaccine?”)
Who should not receive hepas A vaccine?
People who have had a serious allergic reacon to
hepas A vaccine in the past, or who are known
to be allergic to any part of the hepas A vaccine,
should not receive it. People with moderate or severe
acute illness should wait to receive hepas A
vaccine unl their condion has improved.
How eecve is hepas A vaccine?
Hepas A vaccine is very eecve. It appears that
all adults, adolescents, and children become immune
to hepas A virus infecon aer geng two doses.
Aer one dose, at least 94 out of 100 people become
immune for several years. It is important to get the
full two-dose series to ensure long-term protecon.
Can I receive hepas A vaccine when I am
pregnant?
Yes. CDC recommends that a pregnant woman at risk
of hepas A infecon or at risk of a severe outcome
of hepas A infecon during pregnancy should be
vaccinated.
Can the vaccine cause hepas A virus infecon?
No.
Is there a vaccine that protects against both
hepas A and hepas B virus infecon?
Yes. Twinrix is a hepas A and hepas B combina-
on vaccine manufactured by GSK. It 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 protecon against hepas A and
hepas B virus infecons.
What is immune globulin (IG)?
IG is a preparaon of human anbodies that can be
given before exposure to hepas A virus for 1–2
months of protecon against hepas A virus
infecon and to people who have already been
exposed to hepas A virus. IG must be given within
2 weeks aer exposure to the virus for maximum
protecon.
What are the recommendaons for the use of
hepas A vaccine and/or IG prior to travel?
All suscepble people (individuals who have never
had the infecon or the vaccine) traveling to or
working in countries except the United States,
Canada, Japan, New Zealand, Australia, and parts of
Western Europe should receive hepas A vaccine
or IG before departure. If traveling to the Caribbean,
people should consider geng hepas A vaccine or
IG if travel is to areas of unreliable sanitaon.
c on t i n u e d o n t h e n e x t p a g e
www.immunize.org/catg.d/p4204.pdf / Item #P4204 (9/11/2023)
Hepas A: Quesons and Answers (connued) page 5 of 5
www.immunize.org/catg.d/p4204.pdf / Item #P4204 (9/11/2023)
Infants age 6 through 11 months who are at risk of
travel-related exposure to hepas A should receive
1 dose of hepas A vaccine prior to travel, along
with a dose of MMR vaccine to protect against
measles. Hepas A vaccine given before the
rst birthday does not count toward the roune
2-dose series.
For unvaccinated people ages 1 through 40 years, the
rst dose of hepas A vaccine should be given as
soon as travel is considered. The second dose should
be given at least 6 months aer the rst dose.
For the best protecon, healthcare providers caring
for travelers over age 40 and travelers who are
immunocompromised or who have chronic liver
disease, and who are traveling within 2 weeks, may
administer IG in addion to vaccine, depending upon
the paent’s likelihood of a protecve anbody
response to vaccinaon, the availability of IG, and the
risk of hepas A exposure. The second dose of the
2-dose hepas A vaccine series should be given no
sooner than 6 months aer the rst dose. This second
dose is needed to ensure long-lasng protecon.
Travelers who choose not to get the hepas A
vaccine, who are younger than age 6 months, or who
are allergic to the vaccine should be given IG only.
The dosage of IG depends on the length of travel.
Can hepas A vaccine be given aer
exposure to hepas A virus?
Yes. People who recently have been exposed to
hepas A and who previously have not had hepas
A vaccine should be given a single dose of hepas A
vaccine as soon as possible, within 2 weeks of
exposure. For people older than age 40 years, IG
may also be administered at the clinician’s discreon,
but hepas A vaccine can be used alone if IG is
unavailable. IG alone should be given to children
younger than 12 months of age and people for whom
vaccine is contraindicated. Both vaccine and IG
should be given to immunocompromised people and
to people who have chronic liver disease.