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Hepatitis A

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Hepatitis A

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Disease Issues
What is hepatitis A?
Hepatitis A is a liver disease common in many parts of the world and caused by hepatitis A virus (HAV), a picornavirus that causes acute inflammation of the liver. It is not related to the common viruses that cause hepatitis B or C.
What are the signs and symptoms of hepatitis A?
Illness caused by HAV infection cannot be distinguished from other types of acute viral hepatitis, but it typically has an abrupt onset that can include fever, malaise, anorexia, nausea, abdominal discomfort, dark urine, and jaundice. The likelihood of having symptoms with HAV infection is related to age. In children younger than age 6 years, 70% of infections are asymptomatic. When illness does occur in young children, it is typically not accompanied by jaundice. In older children and adults, infection typically is symptomatic, with jaundice occurring in more than 70% of patients.
Hepatitis A signs and symptoms usually resolve in 2–3 months, although 10% to 15% of symptomatic people have prolonged illness (usually referred to as relapsing hepatitis A) lasting up to 6 months and should be considered infectious during that time.
How is HAV transmitted?
Person-to-person spread through the fecal-oral route is the primary means of HAV transmission. Peak infectivity in infected people occurs during the two week period before the onset of jaundice when the concentration of virus in the stool is highest and most people are no longer infectious one week after jaundice onset. Before routine vaccination of children was recommended, children were a key source of infection because most infected children had no symptoms and could shed virus in stool for weeks or months. Transmission currently occurs primarily among susceptible adults.
Common-source outbreaks and sporadic cases can occur from exposure to fecally-contaminated food or water. Uncooked HAV-contaminated foods have been recognized as a source of outbreaks. Cooked foods also can transmit HAV if the temperature during food preparation is inadequate to kill the virus or if food is contaminated after cooking, as occurs in outbreaks associated with infected food handlers. Transmission of the virus from infected food handlers to food service establishment patrons is rare, accounting for 0.2% of the nearly 23,000 outbreak-associated cases of hepatitis A investigated by state health departments during 2016–2019.
Until 2017, US incidence rates of hepatitis A were driven by occasional outbreaks, often linked to viral contamination of imported food. Since 2017, large person-to-person outbreaks have been occurring across the United States, primarily among people who use drugs and people who are experiencing homelessness and unstable living arrangements.
What is the incubation period for hepatitis A?
HAV can produce either asymptomatic or symptomatic infection in humans after an average incubation period of 28 days (range: 15–50 days).
How is HAV shed?
In infected people, HAV replicates in the liver, is excreted in bile, and is shed in stool. Peak infectivity occurs during the 2-week period before onset of jaundice or elevation of liver enzymes, when concentration of virus in stool is highest. Concentration of virus in stool declines after jaundice appears, with most people no longer infectious about a week after jaundice appears. Children can shed HAV for longer periods than adults, up to 10 weeks or longer after onset of clinical illness.
How common is HAV infection in the United States?
In 2017, 3,366 acute clinical cases were reported to CDC's surveillance system. This number is an underestimate of the actual number of infections: CDC estimates that about 6,700 occurred in 2017. Historically, acute hepatitis A rates vary cyclically, with nationwide increases every 10–15 years. The last peak was in 1995; rates of hepatitis A decreased by 95% from 1995 to 2011, then increased by 140% from 2011 to 2017.
 
Do people die from hepatitis A?
Yes. Death as a result of fulminant hepatic failure is rare, however, older age (over 40 years) and preexisting chronic liver disease increases the risk of severe disease and death from hepatitis A. As of June 2020, the person-to-person multistate outbreak that has infected over 33,000 people since 2016 in the United States has disproportionately affected adults with chronic liver disease and other health problems related to drug use and unstable housing. To date, approximately 60% of cases reported as part of that outbreak have been hospitalized and 1% have died.
Who is most at risk for acquiring HAV infection?
People who are at increased risk for acquiring HAV infection include the following:
Travelers to countries that have high or intermediate endemicity of HAV infection
  Men who have sex with men (MSM)
  Users of injection and noninjection drugs (in other words, all who use illegal drugs)
  People with occupational risk of exposure (non-human primates or researchers handling hepatitis A virus)
  People who anticipate close contact with an international adoptee coming from a country with high or intermediate endemicity of HAV infection
  People living with HIV infection
  People experiencing homelessness, including temporary shelters and other unstable living arrangements
  People living in group settings for those with developmental disabilities and other settings where hygiene is difficult to maintain
  People who are incarcerated
I thought people with clotting factor disorders were at risk for hepatitis A due to their regular use of blood products. Why did ACIP decide to stop recommending routine vaccination of people with clotting factor disorders?
People with clotting factor disorders were originally recommended to receive hepatitis A vaccine (HepA) in 1996. At that time, the process used to make clotting factor supplements did not reliably inactivate hepatitis A viruses and recipients of these products had an increased risk of HAV infection. Modern blood donor screening and virus reduction steps have drastically reduced that risk. In addition, more than 80% of people with clotting factor disorders now receive recombinant clotting factor concentrates that are sterilized and have no risk of HAV transmission. As a result of these factors, people with clotting factor disorders now have no greater risk of hepatitis A than the general population and are no longer recommended to receive HepA vaccine unless it is otherwise indicated.
Are people with developmental disabilities at risk of HAV infection?
Historically, HAV infection was highly endemic in institutions for people with developmental disabilities as a result of poor hand hygiene, close living conditions and diaper use. As fewer children have been institutionalized and as conditions in institutions have improved, the incidence and prevalence of HAV infection have decreased, although outbreaks can occur in these settings. All children with developmental disabilities should receive HepA according to U.S. routine vaccine recommendations, including catch up vaccination of all children through age 18 years.
As a strategy to further reduce the risk of hepatitis A outbreaks and reach adults in settings with a high proportion of people with risk factors for HAV infection, the current ACIP recommendations suggest considering HepA vaccination of residents and staff in facilities where hygiene is difficult to maintain, such as group homes for people with developmental disabilities and homeless shelters.
Please discuss the tests commonly used to diagnose hepatitis A.
Hepatitis A cannot be differentiated from other types of viral hepatitis on the basis of clinical or epidemiological features alone. Appropriate blood tests must be used.
Anti-HAV: Total antibody to HAV. This diagnostic test detects total antibody of both IgG and IgM subclasses of HAV. If positive, it indicates either acute or resolved infection.
  IgG anti-HAV: IgG antibody is a subclass of anti-HAV. It appears early in the course of infection, remains detectable for the person's lifetime and provides lifelong protection against disease. Its presence indicates immunity through either HAV infection or HepA vaccination.
  IgM anti-HAV: IgM antibody is a subclass of anti-HAV. Its presence indicates a recent infection with HAV (6 months or less). It is used to diagnose acute (recently acquired) hepatitis A. Because of the risk of false positive IgM anti-HAV results, people should only be tested for IgM anti-HAV if they are symptomatic and suspected of having acute hepatitis A illness.
  HAV RNA tests also may be used to diagnose acute infection through the direct detection of viral RNA in serum or stool.
Total anti-HAV, which appears early in the course of infection, remains detectable for the person's lifetime and indicates lifelong protection against the infection/disease. To confirm a diagnosis of acute HAV infection, serologic testing for IgM anti-HAV is required. In the majority of persons, serum IgM anti-HAV becomes detectable 5 to 10 days before onset of symptoms and lasts about 6 months. However, there have been reports of persons who test positive for IgM anti-HAV for up to a year or more following infection. An educational program on the interpretation of hepatitis A serology is available on the CDC website at www.cdc.gov/hepatitis/resources/professionals/training/serology/training.htm.
Can HAV be transmitted by blood?
Yes. On rare occasions, HAV infection has been transmitted by transfusion of blood or blood products collected from donors during the viremic phase of their infection (i.e., when HAV is in the donor's blood).
Is HAV transmitted by saliva?
In experimentally infected nonhuman primates, HAV has been detected in saliva during the incubation period; however, transmission by human saliva has not been reported.
How common is HAV transmission in hospital settings?
Hospital-acquired HAV infection is rare. In the past, outbreaks were observed in neonatal intensive care units when infants acquired infection from HAV-infected transfused blood and subsequently transmitted HAV to other infants and staff. Outbreaks of hepatitis A caused by transmission from adult patients to healthcare personnel (HCP) are typically associated with fecal incontinence and inadequate hand hygiene, although the majority of hospitalized patients who have hepatitis A are admitted after onset of jaundice, when they are beyond the point of peak infectivity. Transmission in healthcare settings also has resulted from breakdowns in standard infection control practices and transmission from one healthcare provider to another.
How stable is HAV in the environment?
Depending on conditions, HAV can be stable in the environment for months. Heating foods at temperatures greater than 185°F (85°C) for 1 minute or disinfecting surfaces with a 1:100 dilution of sodium hypochlorite (i.e., household bleach) in tap water will inactivate HAV.
Do people with hepatitis A develop chronic disease?
No, there is no chronic (long-term) infection. Even the small proportion of people who develop relapsing HAV recover after about 6 months. Once you have had HAV infection and recovered, you cannot get it again.
Vaccination Recommendations Back to top
What is the best way to prevent HAV infection?
Vaccination with the full series of hepatitis A vaccine (HepA) is the best way to prevent HAV infection. Immune globulin (IG) also can be used for short-term protection in certain situations.
What are the hepatitis A vaccines (HepA) that are approved for use in the United States?
Recommended dosages and schedules of hepatitis A vaccines
Vaccine Age group Dose Volume # Doses Schedule
Havrix
(GSK)
1-18 years 720 El.U.* 0.5 ml 2 0, 6-12 mos.
19 years and older 1440 El.U.* 1.0 ml 2 0, 6-12 mos.
Vaqta
(Merck & Co.)
1-18 years 25 U* 0.5 ml 2 0, 6-18 mos.
19 years and older 50 U* 1.0 ml 2 0, 6-18 mos.

*El.U. = Elisa Units **U = Units

 
Combination vaccine using hepatitis A and hepatitis B vaccines
Vaccine Age group Antigens used Volume # Doses Schedule
Twinrix
(GSK)
18 years and older Havrix (720 El.U.)
combined with
Engerix-B (20 mcg)
1.0 ml 3 0, 1, 6 mos.
4 0, 7, 21-30 days, 12 months
Are HepA vaccine brands interchangeable?
Yes, a number of studies indicate that the two brands of HepA, Havrix (GSK) and Vaqta (Merck), are interchangeable.
Where can I find information about vaccine shortages?
For detailed information about HepA shortages, go to CDC's website at www.cdc.gov/vaccines/hcp/clinical-resources/shortages.html.
Who is recommended to receive HepA vaccine?
The Advisory Committee on Immunization Practices (ACIP) recommends routine HepA vaccination for the following groups:
All children at age 1 year (12–23 months)
  All children and adolescents age 2 through 18 years who have not previously received HepA should be vaccinated (i.e., routine catch-up vaccination) [2020]
  People living with HIV infection [2020]
  Travelers age 12 months and older to areas of the world with intermediate or high HAV endemicity. Low endemicity regions include the United States, Canada, Western Europe, Japan, New Zealand, and Australia. For more information, see the CDC travel health website for current information about specific countries at www.cdc.gov/travel or the CDC Yellow Book (wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/hepatitis-a). When in doubt, vaccinate.
  Infants age 6 through 11 months traveling outside the United States should receive 1 dose when protection against HAV infection is recommended. The travel dose does not count toward the routine HepA series which should be initiated at age 1 year with the appropriate dose and schedule.
  Men who have sex with men
  Users of illegal drugs, injectable or noninjectable
  People who are homeless or in unstable living arrangements, including shelters
  Previously unvaccinated people who anticipate having close personal contact with an international adoptee from a country of high or intermediate endemicity during the first 60 days following the adoptee's arrival in the U.S.
  People who work with nonhuman primates or with HAV in a research laboratory setting
  People with chronic liver disease (including but not limited to people with hepatitis B infection, hepatitis C infection, cirrhosis, fatty liver disease, alcoholic liver disease, autoimmune hepatitis, or an ALT or AST level persistently greater than twice the upper limit of normal)
  Any person who wishes to be immune to hepatitis A
HepA vaccination is not routinely recommended for healthcare personnel, food handlers, sewage workers, or day care providers because there is no evidence that their occupational risks of HAV exposure are significantly higher than the general population. However, any person who desires protection from HAV infection may be vaccinated.
For details about CDC recommendations for the prevention of hepatitis A, see the 2020 recommendations of the Advisory Committee on Immunization Practices (ACIP): www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
What groups of people recommended for routine HepA vaccination were added or removed in the July 2020 ACIP statement?
[added] All children ages 2 through 18 years not previously vaccinated
  [added] All people age 1 year or older living with HIV infection
  [removed] People with clotting factor disorders
Should we give HepA to a person older than age 18 years who requests it?
Yes, unless the person is allergic to any of the vaccine components. HepA vaccination is safe and effective and is recommended for any person who wishes to obtain immunity.
Which children should be routinely vaccinated against HAV infection?
All children should receive 2 doses of HepA vaccine beginning at age 1 year (i.e., 12–23 months). The 2 doses in the series should be administered at least 6 months apart. Any child age 2 through 18 years not previously vaccinated should be vaccinated. For a copy of the ACIP recommendations on hepatitis A, go to www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
For hepatitis A vaccination, the minimum interval between the 2-dose series is at least 6 months. Is this the same as 24 weeks?
No. The minimum interval between dose #1 and #2 of HepA vaccine is 6 calendar months, not 24 weeks.
I have a child who was given her second dose of hepatitis A vaccine 4 months after the first dose. Does it need to be repeated, and if so, when?
The second dose was given more than 4 days before the minimum interval of 6 calendar months, so it is considered invalid and should be repeated. The repeat dose should be administered the proper minimum interval (6 months) after the invalid dose. If this repeat dose is inadvertently given less than 6 months after the invalid dose, it does not need to be repeated again as long as the interval between the initial HepA vaccine and the most recent dose is at least 6 calendar months.
What are the recommendations for postexposure prophylaxis (PEP) for hepatitis A?
In 2020, CDC published revised recommendations for hepatitis A postexposure prophylaxis (PEP). Please see the complete PEP recommendations at www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf, with special attention to Table 4 on page 19 and Appendix B: Provider Guidance on Risk Assessment for Hepatitis A Postexposure Prophylaxis, beginning on page 36.
Healthy people who have completed the HepA vaccination series at any time do not need additional PEP if they are exposed to HAV. People who have recently been exposed to HAV and who have not received HepA vaccine previously should receive PEP as soon as possible, within 2 weeks of exposure.
People age 12 months and older exposed to HAV within the past 14 days and who have not previously completed the HepA vaccine series should receive a single dose of HepA vaccine as soon as possible. In addition to vaccine, immune globulin (IG; 0.1 mL/kg) may be administered to people older than age 40 years depending on the providers' risk assessment. For long-term immunity, the HepA vaccine series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk.
People age 12 months or older who are immunocompromised or have chronic liver disease, and who have been exposed to HAV within the past 14 days and have not previously completed the HepA vaccination series, should receive both IG (0.1 mL/kg) and HepA vaccine at the same visit in a different anatomic site (for example, separate limbs) as soon as possible after exposure. For long-term immunity, the HepA vaccination series should be completed with a second dose at least 6 months after the first dose. However, the second dose is not necessary for PEP. A second dose should not be administered sooner than 6 calendar months after the first dose, regardless of HAV exposure risk.
People with HIV infection develop protective levels of antibody more slowly and are less likely to develop protective antibody levels after vaccination with HepA, especially if their CD4+ count is low at the time of vaccination. Protection following vaccination of a person with HIV may wane over time. Vaccine should be administered if the exposed individual is not fully vaccinated; however, CDC also advises clinicians to consider administering IG PEP to an individual with HIV after a high-risk exposure (such as a household or sexual contact) even if the individual has been fully vaccinated.
Twinrix contains half the amount of hepatitis A antigen as a standard single-dose adult HepA vaccine. Twinrix should not be used for PEP, but may be used to confer protection to at-risk but not yet exposed persons during an outbreak.
Infants younger than age 12 months and persons for whom vaccine is contraindicated should receive IG (0.1 mL/kg) instead of HepA vaccine as soon as possible and within 2 weeks of exposure. MMR and varicella vaccines should not be administered sooner than 6 months after IG administration in order to avoid possible IG interference with the effectiveness of MMR and varicella vaccines.
When should prevaccination anti-HAV testing for susceptibility be performed?
Prevaccination serologic testing for HAV (measuring either total anti-HAV or IgG anti-HAV) is not indicated for children because of the low prevalence of infection in children. It also is not routinely recommended for adults, but may be considered in some settings to reduce costs associated with vaccinating people who are already immune. Prevaccination testing should not be used if it poses a barrier to vaccinating susceptible people, especially people who are difficult to access.
Prevaccination testing is most likely to be cost-effective for adults who were either born in or lived for long periods of time in areas of the world with high or intermediate hepatitis A endemicity. When evaluating people from populations with high rates of previous HAV infection, vaccination history also should be obtained, if feasible. If testing or vaccination history is not available, do not postpone vaccinating. There is no harm in vaccinating a person who has had natural infection or previous doses of vaccine.
When should postvaccination testing be performed?
Serologic testing for immunity is not necessary after routine vaccination of infants, children or adults. Testing for the presence of anti-HAV antibody one month or more after completing the HepA vaccination series is recommended only for people whose future clinical management depends on knowing their immune status and for whom revaccination might be indicated, such as people living with HIV and other immunocompromised persons (such as transplant recipients and people vaccinated while receiving chemotherapy).
If the results of postvaccination testing do not show an adequate immune response (10 mIU/mL or higher), revaccination with a complete series is recommended, followed by a second postvaccination serologic test. If that second test remains negative, no additional vaccination is recommended; however, the patient should be counseled on strategies to avoid exposure to HAV and the need for IG if an exposure occurs. If vaccination results in seroconversion, insufficient data are available to make recommendations concerning repeat testing, booster doses or revaccination.
For Special Groups Back to top
Explain the details regarding the recommendation for giving HepA vaccine to people who will be in contact with recently adopted children.
ACIP recommends vaccination against HAV infection for all previously unvaccinated people who anticipate having close personal contact with an international adoptee from a country of high or intermediate endemicity during the first 60 days following the adoptee's arrival in the U.S. In addition to the adoptee's new parents and siblings, this group might include grandparents, other household members, regular babysitters and other caregivers. The first dose of HepA should be given to close contacts as soon as adoption is planned, ideally at least 2 weeks before the arrival of the adoptee. A second dose should be given no sooner than 6 months after the first dose.
ACIP now recommends routine hepatitis A vaccination for people experiencing homelessness. Can you provide a definition of "experiencing homelessness"?
The 2020 ACIP recommendations for the prevention of hepatitis A define a person experiencing homelessness as 1) a person who lacks housing (regardless of whether the person is a member of a family), including a person whose primary residence during the night is a supervised public or private facility (e.g., shelter) that provides temporary living accommodations and a person who is a resident in transitional housing, 2) a person without permanent housing who might: live on the streets, stay in a shelter, mission, single-room occupancy facility, abandoned building, vehicle, or any other unstable or nonpermanent situation, or 3) who is “doubled up,” a term that refers to a situation where persons are unable to maintain their housing situation and are forced to stay with a series of friends or extended family members. In addition, previously homeless persons who are to be released from a prison or a hospital might be considered homeless if they do not have a stable housing situation to which they can return. The instability of a person's living arrangements is critical to the definition of homelessness.
Some people on my team are worried about initiating the HepA vaccine series in people who are homeless because we may not be able to complete the series or keep up with their records over time. How much of a concern is this?
While a complete series of HepA is recommended for long-term protection, even a single dose of HepA vaccine has been demonstrated to provide protection against hepatitis A for more than 10 years and can prevent or control outbreaks of hepatitis A. People who are experiencing homelessness may have difficulty protecting themselves from exposure to HAV in other ways because of their living conditions. They should be vaccinated when possible and provided a record of immunization. Reporting the HepA vaccination to a state immunization information system also can facilitate immunization assessment at future healthcare encounters.
Should healthcare providers (HCP) be vaccinated routinely against hepatitis A?
No. A number of studies have shown that HCP are not at significantly increased risk of HAV infection because of their occupation. However, if HCPs are going to work (or vacation) in a country with a high or intermediate endemic rate of HAV infection, they are at risk of HAV infection and should be vaccinated. The only occupational indications for routine HepA vaccination are work with non-human primates or live HAV in a laboratory setting.
Should daycare workers be routinely vaccinated against hepatitis A?
No. In the past, outbreaks of hepatitis A occurred among children in child care centers, infecting employees of those centers, especially those caring for infants and toddlers. Following widespread adoption of early childhood vaccination against hepatitis A, outbreaks in child care centers are now rare.
Why is hepatitis A vaccination recommended for people with chronic liver disease?
Although not at increased risk for HAV infection, people with chronic liver disease are at increased risk for fulminant hepatitis A, hospitalization and death if they become infected with HAV. For this reason, hepatitis A vaccination is recommended for them.
Why isn't hepatitis A vaccination recommended for sewage and solid waste disposal workers?
In published reports of three serologic surveys conducted among United States wastewater workers and appropriate comparison populations, no substantial or consistent increase in the prevalence of anti-HAV was identified among wastewater workers. No work-related instances of HAV transmission have been reported among wastewater workers in the United States. In addition, in the United States, outbreaks of hepatitis A caused by flooding, which can carry raw sewage, have not been reported.
Why is hepatitis A vaccination no longer recommended for people with clotting factor disorders?
People with clotting factor disorders were originally recommended to receive hepatitis A vaccine (HepA) in 1996. At that time, the process used to make clotting factor supplements did not reliably inactivate hepatitis A viruses and recipients of these products had an increased risk of HAV infection. Modern blood donor screening and virus reduction steps have drastically reduced that risk. In addition, more than 80% of people with clotting factor disorders now receive recombinant clotting factor concentrates that are sterilized and have no risk of HAV transmission. As a result of these factors, people with clotting factor disorders now have no greater risk of hepatitis A than the general population and are no longer recommended to receive HepA vaccine unless it is otherwise indicated.
Why is hepatitis A vaccination recommended (and IG not recommended) for infant travelers age 6 through 11 months at risk of exposure to HAV?
Because of measles. Measles is highly communicable and poses a serious threat to the health of unvaccinated infants. For this reason, all infants age 6 through 11 months who travel internationally are recommended to receive a dose of measles, mumps, and rubella vaccine (MMR) to reduce the risk of measles infection during travel.
The antibodies in immune globulin (IG) typically used to prevent HAV infection in infants before the first birthday can interfere with the effectiveness of MMR vaccine. An infant who is given IG should not be vaccinated with MMR or varicella vaccines for at least 6 months after IG administration. If an infant age 6 through 11 months is traveling to a destination where protection from infection with HAV is desired, ACIP recommends off-label use of HepA vaccine (not IG) in addition to MMR. The HepA and MMR doses administered before the first birthday do not count toward the routine vaccination series of either vaccine: these infant travelers will still need two doses of HepA and two doses of MMR when age appropriate.
Can pregnant women receive hepatitis A vaccine?
Yes. The ACIP recommends that pregnant women at risk for HAV infection during pregnancy or at risk for a severe outcome from HAV infection should be vaccinated during pregnancy if not previously vaccinated. Pregnant women should be vaccinated for the same indications as non-pregnant women. For additional information, see page 20 of the recommendations: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
Administering Vaccines Back to top
By what method should hepatitis A vaccine be administered?
Hepatitis A vaccine (HepA) should be administered intramuscularly (IM), using the appropriate injection site and needle size as determined by the patient's age and body mass.
Can HepA vaccine be given concurrently with other vaccines?
Yes. Other inactivated and/or live virus vaccines can be administered at the same time as HepA vaccine, but should be given at a different anatomical site, if possible. If given in the same muscle, separate the injections by a minimum distance of 1 inch.
Is HepA vaccine available to children through the Vaccines for Children (VFC) program?
Yes, VFC-supported HepA vaccine is available for children 12 months through 18 years who are VFC-eligible. In addition, combination HepA and HepB vaccine (Twinrix; GSK) is also available for people who are age 18 years who are VFC-eligible.
What happens if dose #2 of HepA vaccine is delayed?
You do not need to start the series over again. The immunogenicity of 1 dose of HepA vaccine is 94% to 100%; studies have shown persistent protection from a single dose lasting more than 10 years. To ensure optimal long-term protection it is important to administer the second dose.
To complete a 21-year-old patient's HepA vaccine series, how many adult doses should I give if the patient received a single dose of pediatric HepA vaccine 5 years ago?
A person should receive the dosage of HepA vaccine appropriate for their age at the time of administration. You should give the patient one adult dose of HepA to complete the 2-dose series. It is not necessary to restart the vaccine series.
One of our staff gave a dose of pediatric HepA vaccine to an adult patient by mistake. How do we remedy this error?
In general, if the error is discovered on the same clinic day, you can administer the other "half" of the dose on that same day. If the error is discovered later, the dose should not be counted, and then the person should be recalled to the office and given a full age-appropriate repeat dose.
If you give more than an age-appropriate dose (for example, an adult dose of HepA vaccine given to a child), count the dose as valid and notify the patient/parent about the error. There may be an increased risk of a local adverse reaction when more than the recommended dose is given. If the error occurred with the first dose of the series the child should still receive the second dose on schedule. Giving a "double" dose for the first dose does not negate the need for a second dose.
Avoid such errors by checking the vaccine vial label 3 times.
Why does a 15-year old who weighs 160 pounds receive a pediatric dose of HepA while his 110-pound mother receives an adult dose (twice the pediatric dose)?
The efficacy data from the clinical trials were based on age at time of vaccination, and not on the weight of the individual. Hence, the dosage recommendations reflect this age-based efficacy data. The same holds true for HepB vaccine. In addition, higher response rates are expected in younger people, even if their weights are above the norm.
Twinrix Back to top
Could you please provide more information about Twinrix (the combination hepatitis A and B vaccine) and the two schedules for its use?
Twinrix (GSK) is an inactivated combination vaccine containing both hepatitis A virus (HAV) and hepatitis B virus (HBV) antigens. The vaccine contains 720 EL.U. of hepatitis A antigen (half of the Havrix adult dose) and 20 mcg of hepatitis B antigen (the full Engerix-B adult dose).
In the U.S., Twinrix is licensed for use in people who are age 18 years or older. It can be administered to people who are at risk for both hepatitis A and hepatitis B, such as certain international travelers, people with HIV infection, people with chronic liver disease not caused by hepatitis B, men who have sex with men, illegal drug users, or to people who simply want to be immune to both diseases. Primary immunization consists of 3 doses given intramuscularly on a 0, 1, and 6 month schedule. In 2007, the FDA also approved a 4-dose schedule for Twinrix. It consists of 3 doses given within 4 weeks, followed by a booster dose at 12 months (0, 7 days, 21–30 days, and 12 months). The 4-dose schedule could benefit individuals needing rapid protection from hepatitis A and hepatitis B, such as people traveling to high-prevalence areas imminently.
Twinrix cannot be used for postexposure prophylaxis.
I have seen adults who have had 1 or 2 doses of Twinrix, but we only carry single-antigen vaccine in our practice. How should we complete their vaccination series with single-antigen vaccines?
Twinrix is licensed as a 3-dose series for people age 18 years and older. If Twinrix is not available or if you choose not to use Twinrix to complete the Twinrix series, you should do the following: If 1 dose of Twinrix was given, complete the series with 2 adult doses of hepatitis B vaccine and 2 adult doses of hepatitis A vaccine. If 2 doses of Twinrix were given, complete the schedule with 1 adult dose of hepatitis A vaccine and 1 adult dose of hepatitis B vaccine.
Another way to consider this is as follows:
A dose of Twinrix contains a standard adult dose of hepatitis B vaccine and a pediatric dose of hepatitis A vaccine. Thus, a dose of Twinrix can be substituted for any dose of the hepatitis B series but not for any dose of the hepatitis A series.
  Any combination of 3 doses of adult hepatitis B or 3 doses of Twinrix is a complete series of hepatitis B vaccine.
  One dose of Twinrix + 2 doses of adult hepatitis A is a complete series of hepatitis A vaccine.
  Two doses of Twinrix + 1 dose of adult hepatitis A is a complete series of hepatitis A vaccine.
We're thinking of using Twinrix and we're wondering whether we can use it for doses #1 and #3 only and use single antigen hepatitis B vaccine for dose #2?
No. Twinrix contains 50% less hepatitis A antigen component than Havrix, GSK's monovalent hepatitis A vaccine [720 vs. 1440 El. U.], so the patient would not receive the recommended dose of hepatitis A vaccine antigen. For this reason, 3 doses of Twinrix must comprise the series.
Immune Globulin Back to top
What is immune globulin (IG)?
Immune globulin (IG, GamaSTAN, Grifols) is a sterile preparation of concentrated antibodies (i.e., immunoglobulins) made from pooled human plasma processed by cold ethanol fractionation. GamaSTAN is the only IG product licensed in the United States for the prevention of hepatitis A. Only plasma that has tested negative for hepatitis B surface antigen, antibody to human immunodeficiency virus (HIV), and antibody to hepatitis C virus (HCV) is used to produce IG. In addition, the Food and Drug Administration requires that the process used to produce IG include a viral inactivation step or that final products test negative for HCV-RNA by polymerase chain reaction. Anti-HAV concentrations differ among IG lots, and decreasing concentrations have been observed over the past 30 years, probably because of the decreasing prevalence of previous HAV infection among plasma donors. In 2017, the dosing of GamaSTAN for HAV prevention was increased to reflect this change in anti-HAV potency.
How does immune globulin (IG) work?
IG provides protection against HAV infection through passive transfer of antibody. Depending on the IG dosage, protection lasts from 1 to 2 months. When administered for preexposure prophylaxis, a dose of 0.1 mL/kg will provide protection for up to 1 month and a dose of 0.2 mL/kg will provide protection for up to 2 months. If longer term protection is required and vaccination is contraindicated, a dose of 0.2 mL/kg can be repeated every 2 months. For postexposure prophylaxis, the recommended dosage is 0.1 mL/kg. There is no maximum dosage of IG for hepatitis A prophylaxis.
How is IG packaged and how is IG administered?
Intramuscular IG is available in single-use vials (2 mL and 10 mL). It should be administered intramuscularly, preferably in the anterolateral aspects of the upper thigh and the deltoid muscle of the upper arm. Do not use the gluteal region as an injection site because of the risk of injury to the sciatic nerve.
Does IG cause adverse events?
Serious adverse events from GamaSTAN IG are rare. Anaphylaxis has been reported after repeated administration to people with known immunoglobulin A (IgA) deficiency; thus, IG should not be administered to these people. IG products including GamaSTAN have been associated with the formation of blood clots (thrombosis) after administration, particularly if the patient has other risk factors for thrombosis. Patients should be counseled about this risk.
Can pregnant or lactating women receive IG?
Yes. Pregnancy or lactation is not a contraindication to IG administration if clearly needed.
A child in my practice was given hepatitis A IG (GamaSTAN, Grifols) when she was 10 months old after her mother tested positive for hepatitis A. She's scheduled for her 12-month-old well-child visit. Will this affect her vaccination schedule?
Yes. IG may be given any time before or after inactivated vaccines. However, the antibodies in IG may interfere with the effectiveness of certain live-virus vaccines, such as measles, mumps, and rubella (MMR) and varicella vaccines. CDC recommends waiting at least 6 months from the date of IG administration before administering MMR and varicella vaccines.
Which people should get GamaSTAN (IG) for prevention of hepatitis A?
Please see details of the recommendations for the use of IG for the prevention of hepatitis A provided in Table 4 (page 19) and Appendices A and B of the 2020 ACIP recommendations for the prevention of hepatitis A infection: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
Below is a brief summary of the recommendations:
Preexposure prophylaxis with IG for travel to areas of intermediate or high hepatitis A endemicity:
Infants younger than age 6 months and other travelers for whom HepA vaccine is declined or contraindicated
  Previously unvaccinated people with chronic liver disease vaccinated within 2 weeks of departure may consider IG in addition to vaccination, based upon the clinician's risk assessment
  Previously unvaccinated people who are immunocompromised may consider IG in addition to vaccination, based upon the clinician's risk assessment
  Previously unvaccinated people who are over age 40 years and vaccinated within 2 weeks of departure may consider IG in addition to vaccination, based upon the clinician's risk assessment
  Infants age 6 through 11 months traveling outside the United States should receive 1 dose when protection against HAV infection is recommended. The travel dose does not count toward the routine HepA series which should be initiated at age 1 year with the appropriate dose and schedule.
Postexposure prophylaxis with IG within 2 weeks after exposure to hepatitis A virus (HAV):
Infants under age 12 months
  Previously unvaccinated immunocompromised adults (including HIV+), in addition to vaccination
  Previously unvaccinated adults with chronic liver disease, in addition to vaccination
  Previously unvaccinated adults over age 40 years, consider IG in addition to vaccination, based upon clinician risk assessment
  People with HIV infection, previously vaccinated, consider IG following a high-risk exposure (household or sexual contact), based upon clinician risk assessment
Travel - International Back to top
Which travelers are recommended to receive HepA vaccine?
Hepatitis A vaccination is recommended for people age 6 months or older who are traveling to or working in an area of the world at intermediate or high risk of hepatitis A transmission. Areas of low risk include the United States, Canada, Japan, New Zealand, Australia and Western Europe. Visit the CDC's Traveler Health website for more information about specific destinations and current outbreaks or travel notices (https://wwwnc.cdc.gov/travel/). When in doubt, vaccinate.
What are the recommendations for vaccination of travelers to protect them from hepatitis A virus (HAV) infection?
For details on preexposure protection of international travelers age 12 months and older, refer to Appendix A on page 35 of the current ACIP recommendations for the prevention of hepatitis A: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
Healthy people age 12 months through 40 years who are planning travel to an area with high or intermediate HAV endemicity and have not received HepA vaccine should receive a single dose of HepA vaccine as soon as travel is considered and should complete the 2-does series according to the routine schedule.
People with chronic liver disease as well as adults older than 40 years of age, immunocompromised persons, and persons with other chronic medical conditions planning to depart to an area with high or intermediate HAV endemicity in less than 2 weeks should receive the initial dose of HepA vaccine, and may also simultaneously be administered IG at a separate anatomic injection site (for example in separate limbs).
ACIP revised its recommendations for preexposure hepatitis A vaccination for travelers in 2018 to include vaccination of infants 6 through 11 months of age. All infants of this age traveling internationally should be given a dose of measles, mumps, rubella vaccine (MMR) before travel. Due to the potential interference of hepatitis A immune globulin (IG) with MMR vaccine effectiveness, an off-label dose of HepA vaccine is recommended instead of IG in this situation. The travel-related dose for infants 6–11 months of age should not be counted toward the routine 2-dose series. The routine 2-dose HepA and MMR vaccination series should be initiated at age 12 months according to the routine, age-appropriate vaccination schedule.
Infants younger than 6 months and travelers who elect not to receive vaccine or for whom vaccine is contraindicated should receive a single 0.1 mL/kg dose of IG before travel when protection against HAV is recommended. If travel is for more than 1 month, a dose of 0.2 mL/kg should be administered. A 0.2 mL/kg dose can be repeated every 2 months for travel of more than 2 months duration.
Can Twinrix be used for people planning international travel?
Yes. If time allows, use the standard Twinrix schedule of 3 doses given intramuscularly on a 0, 1, and 6 month schedule. If travel is imminent the accelerated 4-dose Twinrix schedule can be used, which is 3 doses given on days 0, 7, and 21-30 days and a booster dose at 12 months.
We have an adult patient who received the correct pediatric series of HepA vaccine as a teenager and is now traveling abroad. Does the patient need an adult booster?
No. There is no recommendation for a booster dose of HepA if a patient has completed the 2-dose series at any age.
Is it really necessary to vaccinate travelers to Latin America who will be staying in 4-star hotels?
Yes. Data have shown that people acquire HAV infection even in such places as 4-star hotels located in Latin America.
If a traveler received the first dose of HepA vaccine more than one year ago and needs to travel abroad imminently, will the traveler need IG in addition to dose #2 prior to leaving?
No. Just give the final dose of HepA vaccine prior to travel.
If an infant younger than age 6 months receives IG before travel to a hepatitis A endemic area, will he/she need HepA vaccine before another trip to a hepatitis A endemic area?
Possibly. Since IG protects against HAV infection for only 1 to 2 months, depending on the dosage given, additional IG may be needed if the infant is not yet age 6 months. Once the child has reached six months of age, HepA vaccine should be given.
Can VFC-eligible children who travel to HAV-endemic areas receive HepA vaccine under the VFC program?
Yes. ACIP recommends that all children age 1 year through 18 years should be vaccinated against hepatitis A. VFC HepA vaccine may be administered to any eligible child, including those recommended for vaccination at 6 through 11 months of age as a result of travel to an HAV-endemic area.
If a person was born and grew up in a country where HAV infection is endemic (e.g., Vietnam, Mexico) and then moved to the United States at age 20, should that person receive HepA vaccine before returning to visit his/her homeland?
It depends on whether that person has a history of HAV infection. Unless there are medical records that document prior HAV infection, serologic testing for immunity (positive test for total anti-HAV) is the only way to determine if vaccination is necessary. For people from countries with high rates of HAV infection, such as Vietnam and Mexico, serologic testing might be done to prevent unnecessary vaccination. The cost effectiveness of serologic testing, however, should be balanced against the possibility of delaying needed vaccination while awaiting test results.
If a person has had HAV infection, should they still receive the vaccine if planning international travel?
No, as long as there are medical records that document that the person was previously infected with HAV (i.e., positive test for total anti-HAV). If there is any doubt that the person actually was infected with HAV, HepA vaccine and/or IG should be given. The vaccine or IG will not harm a person who is already immune.
Vaccine Safety Back to top
What reactions might occur after administration of HepA vaccine?
No serious adverse events have been attributed definitively to HepA vaccine. Among adults, the most frequently reported side effects are soreness at the site of the injection and headache. In children, the most frequently reported side effect is soreness at the injection site. The frequency of side effects after administration of Twinrix is similar to those reported when the two single-antigen vaccines were administered.
Contraindications and Precautions Back to top
What contraindications and precautions should be followed when administering HepA vaccine?
Hepatitis A vaccine is contraindicated for people with a history of a severe allergic reaction to a previous dose of HepA vaccine or to a vaccine component. As with all other vaccines, there is a precaution when giving it to anyone who is moderately or severely ill.
Can pregnant women receive HepA vaccine?
Yes. ACIP recommends that pregnant women at risk for HAV infection during pregnancy or at risk for a severe outcome from HAV infection should be vaccinated during pregnancy if not previously vaccinated. Pregnant women should be vaccinated for the same indications as non-pregnant women. For additional details, see page 20 of the current ACIP recommendations: www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6905a1-H.pdf.
Can lactating women receive HepA vaccine?
Yes. HepA vaccine is an inactivated vaccine and poses no harm to the nursing infant.
Can HepA vaccine be given to immunocompromised people?
Yes. All people age 1 year or older living with HIV infection should be vaccinated against hepatitis A if they have not been vaccinated, regardless of their CD4+ count.
If any immunocompromised person has a risk factor that places them at increased risk of hepatitis A (e.g., international travel, drug use), they should be vaccinated with HepA vaccine.
I have a patient on interferon for hepatitis C, but I want to give him HepA vaccine. Is it okay to vaccinate him against hepatitis A while he is on interferon?
Yes. HepA vaccine should be given to all susceptible patients with chronic liver disease. HepA vaccine is very immunogenic.
Vaccine Storage and Handling Back to top
How should HepA vaccine be stored?
All hepatitis A-containing vaccine should be stored at refrigerator temperature at 2°C to 8°C (36°F to 46°F). The vaccine must not be frozen. Any vaccine exposed to freezing temperature should not be used. Do not use these or any other vaccines after the expiration date shown on the packaging. Any vaccine administered after its expiration date is not valid and should be repeated.
 
This page was updated on July 31, 2020.
This page was reviewed on July 31, 2020.
 
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