Hepatitis A Questions and Answers for Health Professionals

Index of Questions

Overview and Statistics

What is the case definition for acute hepatitis A?

The 2019 case definition for acute hepatitis A:*

Clinical Criteria

  • An acute illness with a discrete onset of any sign or symptom consistent with acute viral hepatitis (e.g., fever, headache, malaise, anorexia, nausea, vomiting, diarrhea, abdominal pain, or dark urine)
a) jaundice or elevated total bilirubin levels ≥ 3.0 mg/dL, OR
b) elevated serum alanine aminotransferase (ALT) levels >200 IU/L
c) the absence of a more likely diagnosis

Laboratory Criteria for Diagnosis
Confirmatory laboratory evidence:

  • Immunoglobulin M (IgM) antibody to hepatitis A virus (anti-HAV) positive,
  • Nucleic acid amplification test (NAAT; such as polymerase chain reaction [PCR] or genotyping) for hepatitis A virus RNA positive

Case Classification – Confirmed

  • A case that meets the clinical criteria and is IgM anti-HAV positive† OR
  • A case that has hepatitis A virus RNA detected by NAAT (such as PCR or genotyping) OR
  • A case that meets the clinical criteria and occurs in a person who had contact (e.g., household or sexual) with a laboratory-confirmed hepatitis A case 15–50 days prior to onset of symptoms

*Per the Council of State and Territorial Epidemiologists (CSTE)
And not otherwise ruled out by IgM anti-HAV or NAAT for hepatitis A virus testing performed in a public health laboratory

How do I learn more about hepatitis A serology?

CDC offers an online training that covers hepatitis A serology.

How common is hepatitis A in the United States?

In 2017, a total of 3,366 cases of hepatitis A were reported in the United States, but due to underreporting, the actual number of cases is likely around 6,700 (1). Incidence decreased more than 95% from 1995 to 2011, then increased by 140% from 2011 to 2017. In 2016,  large person-to-person outbreaks began occurring.


Incidence of hepatitis A - United States, 2011-2018. Line graph with years along the x axis and reported cases along the y axis.  Line is around 50,000 for years 2011-2016, increase to 100,000 in 2017 and around 380,000 in 2018.

How is the hepatitis A virus transmitted?

Hepatitis A is transmitted through the fecal-oral route. This can happen through:

  • Close person-to-person contact with an infected person
  • Sexual contact with an infected person
  • Ingestion of contaminated food or water

Although viremia occurs early in infection, current data indicate that bloodborne transmission of hepatitis A virus is uncommon.

Who is at increased risk for acquiring hepatitis A virus (HAV) infection?

  • Persons with direct contact with persons who have hepatitis A
  • Travelers to countries with high or intermediate endemicity of HAV infection
  • Men who have sex with men
  • Users of injection and non-injection drugs
  • Persons with clotting factor disorders
  • Persons working with nonhuman primates
  • Household members and other close personal contacts of adopted children newly arriving from countries with high or intermediate hepatitis A endemicity

(Prevention of Hepatitis A Through Active or Passive Immunization Recommendations of the Advisory Committee on Immunization Practices [ACIP];  Prevention of Hepatitis A Through Active or Passive Immunization: Recommendations of the Advisory Committee on Immunization Practices)

What are the signs and symptoms of  hepatitis A virus infection?

Among older children and adults, infection is typically symptomatic. Symptoms usually occur abruptly and can include the following:

  • Fever
  • Fatigue
  • Loss of appetite
  • Nausea
  • Vomiting
  • Abdominal pain
  • Dark urine
  • Diarrhea
  • Clay-colored stool
  • Joint pain
  • Jaundice

Most (70%) of infections in children younger than age 6 are not accompanied by symptoms. When symptoms are present, young children typically do not have jaundice; most (>70%) older children and adults with HAV infection have this symptom (7,8).

When symptoms occur, how long do they last?

Symptoms of hepatitis A usually last less than 2 months, although 10%–15% of symptomatic persons have prolonged or relapsing disease for up to 6 months (913).

What is the incubation period for hepatitis A virus (HAV)?

The average incubation period for HAV is 28 days (range: 15–50 days) (9,10,11).

How long does hepatitis A virus (HAV) survive outside the body?

HAV can live outside the body for months, depending on the environmental conditions (12).

How is the hepatitis A virus (HAV) killed?

In contaminated food, HAV is killed when exposed to temperatures of >185 degrees F (>85 degrees C) for 1 minute (13). However, the virus can still be spread from cooked food that is contaminated after cooking. Freezing does not inactivate HAV.

Adequate chlorination of water, as recommended in the United States, kills HAV that enters the municipal water supply (14,15,16). Transmission of HAV from exposure to contaminated water is rare (17).

Can hepatitis A become chronic?

No. Hepatitis A does not become a chronic, long-term, infection.

Can someone become re-infected with the hepatitis A virus?

No. Immunoglobulin G antibodies to the hepatitis A virus, which appear early in the course of infection, provide lifelong protection against the disease (5).

How is hepatitis A virus infection prevented?

Vaccination with the full, two-dose series of hepatitis A vaccine is the best way to prevent infection. Hepatitis A vaccine has been licensed in the United States for use in people 1 year of age and older. Additional guidance is available in Recommendations of the ACIP.

Immune globulin can provide short-term protection against hepatitis A, both pre- and postexposure. Immune globulin must be administered within 2 weeks after exposure for maximum protection. Additional guidance is available in MMWR: Updated Dosing Instructions for Immune Globulin (Human) GamaSTAN S/D for Hepatitis A Virus Prophylaxis. Given that the virus is transmitted through the fecal-oral route, good hand hygiene—including handwashing after using the bathroom, changing diapers, and before preparing or eating food—is integral to hepatitis A prevention.

Hepatitis A Vaccination

Who should be vaccinated against hepatitis A?

The Advisory Committee on Immunization Practices (ACIP) recommends that the following people be vaccinated against hepatitis A:

  • All children at age 12–23 months
  • Unvaccinated children and adolescents aged 2–18 years
  • People experiencing homelessness
  • Infants from 6–11 months of age traveling internationally where hepatitis A vaccine is recommended
  • Healthy travelers from 12 months to 40 years of age going to a country with high or intermediate endemicity of hepatitis A
  • Men who have sex with men
  • People who use injection and non-injection drugs (i.e., any illicit drug)
  • People who have occupational risk for infection (e.g., work with primates infected with the hepatitis A virus (HAV) or with HAV in a research laboratory setting)
  • People who have chronic liver disease
  • People who anticipate close contact with an adoptee from a country with high or intermediate endemic hepatitis A
  • People with HIV
  • People with direct contact with people who have hepatitis A (postexposure prophylaxis)
  • Any person wishing to obtain immunity (protection)

What if an infant receives the first dose of hepatitis A vaccine at an age younger than 12 months?

Although no known harm is associated with giving hepatitis A vaccine to infants, the hepatitis A vaccine dose(s) administered prior to 12 months of age might result in a suboptimal immune response, particularly in infants with passively acquired maternal antibody (18,19). Therefore, hepatitis A vaccine dose(s) administered at <12 months of age are not considered valid doses.

The two-dose hepatitis A vaccine series should be initiated starting at least 6 months after the last invalid dose and when the child is at least 1 year of age.

Which hepatitis A vaccines are licensed for use in the United States?

The U.S. Food and Drug Administration has licensed two single-antigen hepatitis A vaccines and one combination vaccine for use in the United States. All are inactivated vaccines.

What are the schedules for hepatitis A vaccines?

For detailed information on hepatitis A vaccine schedules, see Immunization Schedules for Children or Immunization Schedules for Adults

How long does protection from hepatitis A vaccine last?

The exact duration of protection against hepatitis A virus infection after vaccination is unknown. Anti-HAV has been shown to persist for at least 20 years in most people receiving the 2-dose series as infants <2 years of age (20), those vaccinated with a 3-dose series as young children (aged 3–6 years) (21,22), and adults receiving the entire vaccine series during adulthood (23,24).

Can hepatitis A vaccine be administered concurrently with other vaccines?

Yes. Hepatitis B, diphtheria, poliovirus (oral and inactivated), tetanus, typhoid (oral and intramuscular), cholera, Japanese encephalitis, rabies, and yellow fever vaccines can be given at the same time that hepatitis A vaccine is given (25). In studies among young children, simultaneous administration of hepatitis A vaccine did not affect the immunogenicity or reactogenicity of diphtheria-tetanus-acellular pertussis; inactivated polio; measles, mumps, rubella (MMR); hepatitis B; and Haemophilus influenzae type b vaccines (26,27,28).

Can a patient receive the first dose of hepatitis A vaccine from one manufacturer and the second (last) dose from another manufacturer?

Ideally, doses of vaccine in a series come from the same manufacturer; however, if this is not possible or if the manufacturer of doses given previously is unknown, providers should administer the vaccine that they have available (25). The dose should be considered valid and does not need to be repeated.

What should be done if the second (last) dose of hepatitis A vaccine is delayed?

The second dose should be given as soon as possible. Even if the second dose is delayed, the first dose does not need to be repeated.

Are there people who should not receive the hepatitis A vaccine?

Information regarding people who should not receive the hepatitis A vaccine is provided in the Vaccine Information Statement for Hepatitis A.

Can hepatitis A vaccine be given during pregnancy?

Yes. Pregnant women should be vaccinated for the same indications as non-pregnant women. Unvaccinated or partially vaccinated pregnant adolescents should receive catch-up hepatitis A vaccination. See Adult Immunization Schedule by Medical and Other Indications. Pregnant women at risk for hepatitis A during pregnancy should also be counseled concerning all options for preventing infection.

Can hepatitis A vaccine be given to people who are immunocompromised (e.g., people on hemodialysis or people with HIV)?

Yes. Because hepatitis A vaccine is inactivated, no special precautions need to be taken when vaccinating people who are immunocompromised. After completing the 2-dose vaccine series, most people who are immunocompromised do not need additional vaccine. The Advisory Committee on Immunization Practices (ACIP) now recommends that all people with HIV aged ≥1 year receive hepatitis A vaccine.

Is it harmful to administer an extra dose(s) of hepatitis A vaccine or to repeat the entire vaccine series if documentation of vaccination history is unavailable?

No. If necessary, administering extra doses of hepatitis A vaccine is not harmful.

What adverse events have been associated with hepatitis A vaccination?

The most frequently reported adverse events associated with monovalent hepatitis A vaccination are fever, injection site reactions, and rash. Any adverse event suspected to be associated with hepatitis A vaccination should be reported through the Vaccine Adverse Event Reporting Systemexternal icon (VAERS).

Is it worthwhile to administer the first dose of hepatitis A vaccine if the timing of the second dose cannot be ensured?

Yes. It is not known for how long protection from one hepatitis A vaccine dose lasts, but it has been shown to last for at least 10 years (29).

Should prevaccination testing be performed before administering hepatitis A vaccine?

Prevaccination serologic testing for hepatitis A immunity prior to vaccination is not routinely recommended. However, it may be considered in specific settings or populations when the cost of vaccinating people who are already immune is a concern. People for whom prevaccination testing will likely be most cost-effective include adults who were either born in or lived for extensive periods in geographic areas that have a high or intermediate endemicity of hepatitis A. Vaccination should not be postponed if vaccination history cannot be obtained, records are unavailable, or prevaccination testing is not feasible.

Additional information is available: Recommendations of the ACIP: Prevention of Hepatitis A Through Active or Passive Immunization

Should postvaccination testing be performed?

Serologic testing for immunity is not necessary after routine vaccination of infants, children, or adults.

Additional information is available: Recommendations of the ACIP: Prevention of Hepatitis A Through Active or Passive Immunization

Is hepatitis A vaccine recommended for people displaced by a disaster or affected by flood?

Although hepatitis A vaccine is recommended for all children in the United States at age 1 year (i.e., 12–23 months) and high-risk adults, evacuation itself is not a specific indication for hepatitis A vaccination of previously unvaccinated children or adults unless exposure to hepatitis A virus is suspected. Additional information is available: Interim Immunization Recommendations for Individuals Displaced by a Disaster. In the United States, floods, which may carry raw sewage, are unlikely to cause outbreaks of communicable diseases, and outbreaks of hepatitis A caused by flooding have not been documented (Floodwater After a Disaster or Emergency).

Do health-care personnel need routine vaccination against hepatitis A?

No. Hepatitis A vaccine is not routinely recommended for health-care personnel, because health-care-associated transmission of hepatitis A virus is rare in the United States.

Which groups are at low risk and do NOT need routine vaccination against hepatitis A?

  • People with clotting-factor disorders.  Although this group was once recommended to receive routine vaccination, the risk for hepatitis A virus (HAV) transmission via transfusion of blood products among people with clotting factor disorders is now considered the same as that among the general population (30). Source plasma is now screened for HAV (31). More information can be found within CDC’s published vaccine schedules.  
  • Food handlers.  Hepatitis A vaccination is not specifically recommended for people who handle food in the absence of other risk factors. Foodborne hepatitis A outbreaks occur relatively infrequently in the United States. It is rare for food handlers with HAV infection to transmit HAV through their workplace to customers. Food handlers are not at increased risk for hepatitis A because of their occupation (32).
  • Workers exposed to sewage. In the United States, no work-related outbreaks of hepatitis A have been reported among workers exposed to sewage. Studies on the incidence of clinical HAV infection do not show an increased risk in workers exposed to sewage. People who work with sewage (e.g., plumbers) also are not at risk for HAV infection (33).
  • Health-care personnel. Hepatitis A vaccine is not routinely recommended for health-care personnel, because health-care-associated HAV transmission is rare. Health-care personnel should be encouraged to adhere to recommended infection control practices, standard precautions, and contact precautions for incontinent patients, including hand hygiene (34).
  • Child-care–center staff. Hepatitis A outbreaks in child-care centers are now rare in the United States, and routine vaccination of child-carecenter staff is not warranted. Hepatitis A vaccination is recommended for all children at 1 year of age, including children attending child-care centers.

Immune Globulin

What Immune Globulin product is licensed in the United States?

GamaSTAN™ S/D is the only immune globulin (IG) product approved by the U.S. Food and Drug Administration (FDA) for hepatitis A virus prophylaxis. GamaSTAN™ S/D (Grifols Therapeutics, Inc., Research Triangle Park, North Carolina) is a sterile, preservative-free solution of IG for intramuscular administration and is used for prophylaxis against disease caused by infection with hepatitis A, measles, varicella, and rubella viruses. S/D  More information on GamaSTAN™ is available from FDA pdf icon[PDF – 8 pages]external icon.

What dose of immune globulin should be used for pre- and postexposure hepatitis A prophylaxis?

In July 2017, the prescribing information for GamaSTAN™ S/D was updated. Changes were made to the dosing instructions for hepatitis A pre- and postexposure prophylaxis indications. These changes were made because of concerns about decreased HAV immunoglobulin G antibody (anti-HAV IgG) potency, likely resulting from decreasing prevalence of previous HAV infection among plasma donors, leading to declining anti-HAV antibody levels in donor plasma (36).  More dosing information is available in the table below and in Updated Dosing Instructions for Immune Globulin (Human) GamaSTAN S/D for Hepatitis A Virus Prophylaxis.

Indications and dosage recommendations for GamaSTAN S/D human immune globulin for preexposure and postexposure prophylaxis against hepatitis A infection
Indication Dose
Preexposure prophylaxis
Up to 1 month of travel 0.1 mL/kg
Up to 2 months of travel 0.2 mL/kg
2 months of travel or longer 0.2 mL/kg (repeat every 2 months)
Postexposure prophylaxis 0.1 mL/kg

Postexposure Prophylaxis for Hepatitis A

What are the current CDC guidelines for postexposure protection against hepatitis A?

Hepatitis A vaccine should be administered as soon as possible, within 2 weeks of exposure, to all unvaccinated people aged ≥12 months who have recently been exposed to hepatitis A virus (HAV). In addition to hepatitis A vaccine, co-administration of GamaSTAN S/D immune globulin (0.1 mL/kg) is recommended under certain circumstances according to age and health status of the exposed person.

Should patrons of an establishment implicated in an outbreak of hepatitis A receive postexposure prophylaxis (PEP)?

Because common-source transmission to patrons is unlikely, PEP administration to patrons is typically not indicated. However, PEP may be considered for those patrons potentially exposed to a symptomatic food handler if a) the food handler directly handled uncooked or cooked foods without gloves AND had diarrhea or poor hygienic practices and b) the patron can be identified and treated within 2 weeks of exposure, though the risk to these patrons still remains low (36).

In settings in which repeated exposures to hepatitis A virus might have occurred (e.g., institutional cafeterias), consideration of PEP use is warranted. PEP in this scenario should generally consist of vaccination for all age groups, though immune globulin may be considered for exposed people (patrons during the time the food handler was symptomatic and worked) who are immunocompromised or have chronic liver disease.

What should be done when a case of hepatitis A is found in a setting providing services to children or adults (e.g., a school, hospital, office setting, corrections facility, or homeless shelter)?

  • Postexposure prophylaxis (PEP) is not routinely indicated when a single case occurs in an elementary or secondary school or an office or other work setting and the source of infection is outside of the setting.
  • When a person who has HAV infection is admitted to a hospital, staff members should not routinely be administered PEP; instead, appropriate infection control practices should be emphasized (see standard and contact precautions for diapered or incontinent patients).
  • PEP should be administered to people who have close contact with index patients if an epidemiologic investigation indicates HAV transmission has occurred among students in a school or among patients or between patients and staff members in a hospital.
  • PEP should be considered for all previously unvaccinated residents and employees when a confirmed hepatitis A case occurs in a setting where close personal contact occurs regularly and hygiene standards are difficult to maintain (e.g., correctional facility, homeless shelter, psychiatric facility, group home or residential facility for the disabled). In a setting containing multiple enclosed units or sections (e.g., prison ward), PEP administration should be limited only to people in the area where there is exposure risk.

Do immunocompromised people require additional protection after being exposed to someone with hepatitis A?

Yes. People who are immunocompromised or have chronic liver disease and who have been exposed to hepatitis A virus within the past 2 weeks and have not previously completed the 2-dose hepatitis A vaccination series should receive both immune globulin (0.1 mL/kg) and hepatitis A vaccine simultaneously in a different anatomic site (e.g., separate limbs) as soon as possible after exposure. When the dose of hepatitis A vaccine administered is the first dose the exposed individual has received, a second dose should be administered 6 months after the first for long-term protection.

Should pregnant women at increased risk for exposure to the hepatitis A virus (HAV) receive postexposure prophylaxis?

Women with increased likelihood of exposure to HAV during pregnancy can be administered immune globulin (0.1 mL/kg). There has been no observed increase in maternal or infant adverse events after hepatitis A vaccination or IG administration in pregnancy.

Hepatitis A and International Travel

Who should receive protection against hepatitis A virus (HAV) before travel?

All susceptible people (i.e., unvaccinated or never infected) traveling to or working in countries that have high or intermediate HAV endemicity are at increased risk for HAV infection. These travelers should be vaccinated or receive immune globulin (if too young or contraindicated for vaccine) before departure (37,38). For more information on international travel and hepatitis A, see CDC’s travel page or ACIP updated recommendations on Prevention of Hepatitis A after Exposure to Hepatitis A Virus and in International Travelers.

How soon before international travel should the first dose of hepatitis A vaccine be given?

All unvaccinated people ≥12 months of age (including those with immunocompromising conditions and people with chronic liver disease) planning travel to an area with high or intermediate HAV endemicity should receive a single dose of vaccine as soon as travel is considered; they should then complete the vaccine series with the appropriate dose and schedule. People traveling within 2 weeks (i.e., <2 weeks) should receive the initial dose of hepatitis A vaccine before departure and also simultaneously may be administered IG at a separate anatomic injection site (e.g., separate limbs) for additional short-term protection (38,39,40,41). The hepatitis A vaccine series should be completed according to the routine schedule. Information on immune globulin dosing and additional information on hepatitis A vaccine and travel is available.

What should be done to protect international travelers <6 months of age and other travelers unable to receive hepatitis A vaccine?

Infants aged <6 months and travelers for whom vaccine is contraindicated or who elect not to receive vaccine should receive immune globulin before travel when protection against hepatitis A virus is recommended. Information on immune globulin dosing is available.

What should be done to protect international travelers 6–11 months of age?

Hepatitis A vaccine should be administered to infants aged 6–11 months traveling outside the United States when protection against hepatitis A is recommended. This vaccine dose does not count towards the 2-dose series. The 2-dose hepatitis A vaccine series should then be initiated at age 12 months (at any interval after the dose administered for international travel preexposure prophylaxis) according to the routine, age-appropriate vaccine schedule. Click for Additional information on protection against hepatitis A before travel.


  1. Viral hepatitis surveillance—United States, 2017. Atlanta: US Department of Health and Human Services, Centers for Disease Control and Prevention; 2019. Available at: /hepatitis/statistics/2017surveillance/index.htm.
  2. Hadler SC, Webster HM, Erben JJ, Swanson JE, Maynard JE. Hepatitis A in day-care centers: a community-wide assessment. New England J Med 1980;302(22):1222–
  3. Lednar WM, Lemon SM, Kirkpatrick JW, Redfield RR, Fields ML, Kelley PW. Frequency of illness associated with epidemic hepatitis A virus infections in adults. Am J Epidemiol 1985;122(2):226–
  4. Tong MJ, el-Farra NS, Grew MI. Clinical manifestations of hepatitis A: recent experience in a community teaching hospital. J Infect Dis 1995;171 Suppl 1:S15–
  5. Koff RS. Clinical manifestations and diagnosis of hepatitis A virus infection. Vaccine. 1992;10 Suppl 1:S15–
  6. Sjogren MH, Tanno H, Fay O, et al. Hepatitis A virus in stool during clinical relapse. Ann Intern Med 1987;106(2):221–
  7. Gordon SC, Reddy KR, Schiff L, Schiff ER. Prolonged intrahepatic cholestasis secondary to acute hepatitis A. Ann Intern Med 1984;101(5):635–
  8. Schiff ER. Atypical clinical manifestations of hepatitis A. Vaccine 1992;10 Suppl 1:S18–
  9. Halliday ML, Kang LY, Zhou TK, et al. An epidemic of hepatitis A attributable to the ingestion of raw clams in Shanghai, China. J Infect Dis 1991;164(5):852–9.
  10. Neefe JR, Gellis SS, Stokes J Jr. Homologous serum hepatitis and infectious (epidemic) hepatitis: studies in volunteers bearing on immunological and other characteristics of the etiological agents. Am J Med 1946;1:3–22.
  11. Krugman S, Giles JP, Hammond J. Infectious hepatitis. Evidence for two distinctive clinical, epidemiological, and immunological types of infection. JAMA 1967;200(5):365–73.
  12. Abad FX, Pinto RM, Bosch A. Survival of enteric viruses on environmental fomites. Appl Environ Microbiol 1994;60(10):3704–10.
  13. Wasley A, Fiore A, Bell BP. Hepatitis A in the era of vaccination. Epidemiol Rev 2006;28:101–11. Epub 2006 Jun 14. Review.
  14. Millard J, Appleton H, Parry JV. Studies on heat inactivation of hepatitis A virus with special reference to shellfish. Part 1. Procedures for infection and recovery of virus from laboratory-maintained cockles. Epidemiol Infect 1987;98(3):397–414.
  15. Griffin DW, Donaldson KA, Paul JH, Rose JB. Pathogenic human viruses in coastal waters. Clin Microbiol Rev 2003;16(1):129–43.
  16. Murphy P, Nowak T, Lemon SM, Hilfenhaus J. Inactivation of hepatitis A virus by heat treatment in aqueous solution. J Med Virol 1993;41(1):61–4.
  17. Barrett CEexternal icon, Pape BJexternal icon, Benedict KMexternal icon, et al. Impact of public health interventions on drinking water-associated outbreaks of hepatitis A—United States, 1971–2017. MMWR 2019;68(35):766–70.
  18. Letson GW, Shapiro CN, Kuehn D, et al. Effect of maternal antibody on immunogenicity of hepatitis A vaccine in infants. J Pediatr 2004;144:327–32.
  19. Dagan R, Amir J, Mijalovsky A, et al. Immunization against hepatitis A in the first year of life: priming despite the presence of maternal antibody. Pediatr Infect Dis J 2000;19:1045–52.
  20. Spradling PR, Bulkow LR, Negus SE, Homan C, Bruce MG, McMahon BJ. Persistence of seropositivity among persons vaccinated for hepatitis A during infancy by maternal antibody status: 15-year follow-up. Hepatology 2016;63(3):703–11.
  21. Plumb ID, Bulkow LR, Bruce MG, et al. Persistence of antibody to hepatitis A virus 20 years after receipt of Hepatitis A vaccine in Alaska. J Viral Hepatol 2017;24(7):608–12.
  22. Mosites E, Gounder P, Snowball M, et al. Hepatitis A vaccine immune response 22 years after vaccination. J Medical Virol 2018;90(8):1418–22.
  23. Hens N, Habteab Ghebretinsae A, Hardt K, Van Damme P, Van Herck K. Model based estimates of long-term persistence of inactivated hepatitis A vaccine-induced antibodies in adults. Vaccine 2014;32(13):1507–13.
  24. Theeten H, Van Herck K, Van Der Meeren O, Crasta P, Van Damme P, Hens N. Long-term antibody persistence after vaccination with a 2-dose Havrix™ (inactivated hepatitis A vaccine): 20 years of observed data, and long-term model-based predictions. Vaccine 2015;33(42):5723–7.
  25. Ezeanolue E, Harriman K, Hunter P, Kroger A, Pellegrini C. General Best Practice Guidelines for Immunization: Best practices guidance of the Advisory Committee on Immunization Practices (ACIP). Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/index.html.
  26. Letson GW, Shapiro CN, Kuehn D, et al. Effect of maternal antibody on immunogenicity of hepatitis A vaccine in infants. J Pediatr 2004;144:327–32.
  27. Nolan T, Bernstein H, Blatter MM, et al. Immunogenicity and safety of an inactivated hepatitis A vaccine administered concomitantly with diphtheria-tetanus-acellular pertussis and Haemophilus influenzae type B vaccines to children less than 2 years of age. Pediatrics 2006;118(3):e602–9.
  28. Usonis V, Meriste S, Bakasenas V, et al. Immunogenicity and safety of a combined hepatitis A and B vaccine administered concomitantly with either a measles-mumps-rubella or a diphtheria-tetanus-acellular pertussis-inactivated poliomyelitis vaccine mixed with a Haemophilus influenzae type b conjugate vaccine in infants aged 12–18 months. Vaccine 2005;23(20):2602–6.
  29. Ott JJ, Wiersma ST. Single-dose administration of inactivated hepatitis A vaccination in the context of hepatitis A vaccine recommendations. Int J Infect Dis 2013;17(11):e939–44.
  30. Klamroth R, Groner A, Simon TL. Pathogen inactivation and removal methods for plasma-derived clotting factor concentrates. Transfusion 2014;54(5):1406–17.
  31. Groner A. Pathogen safety of plasma-derived products—Haemate P/Humate-P. Haemophilia 2008;14 Suppl 5:54–71.
  32. Fiore AE. Hepatitis A transmitted by food. Clinical Infect Dis 2004;38(5):705–15.
  33. Glas C, Hotz P, Steffen R. Hepatitis A in workers exposed to sewage: a systematic review. Occup Environ Med 2001;58(12):762–8. Review.
  34. Siegel JD, Rhinehart E, Jackson M, Chiarello L. 2007 Guideline for isolation precautions preventing transmission of infectious agents in healthcare settings. Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/infectioncontrol/guidelines/isolation/index.html.
  35. Ajmera V, Xia G, Vaughan G, et al. What factors determine the severity of hepatitis A-related acute liver failure. J Viral Hepatol 2011;18(7):e167–74.
  36. Ridpath A, Reddy V, Layton M, et al. Hepatitis A Cases Among Food Handlers: A Local Health Department Response—New York City, 2013. J Public Health Manag Pract 2017;23(6):571–6.
  37. Nelson NP, Link-Gelles R, Hofmeister MG, et al. Update: Recommendations of the Advisory Committee on Immunization Practices for use of hepatitis A vaccine for postexposure prophylaxis and for preexposure prophylaxis for international travel. MMWR 2018;67:1216–1220. DOI: http://dx.doi.org/10.15585/mmwr.mm6743a5external icon
  38. Nelson NP. Updated Dosing Instructions for Immune Globulin (Human) GamaSTAN S/D for hepatitis A virus prophylaxis. MMWR 2017;66(36):959–60.
  39. Keeffe EB, Iwarson S, McMahon BJ, et al. Safety and immunogenicity of hepatitis A vaccine in patients with chronic liver disease. Hepatology 1998;27(3):881–6.
  40. Lee SD, Chan CY, Yu MI, Wang YJ, Chang FY, Lo KJ, et al. Safety and immunogenicity of inactivated hepatitis A vaccine in patients with chronic liver disease. J Med Virol 1997;52(2):215–8.
  41. a id=”ref041″ name=”ref41″>Buxton JA, Kim JH. Hepatitis A and hepatitis B vaccination responses in persons with chronic hepatitis C infections: a review of the evidence and current recommendations. Can J Infect Dis Med Microbiol 2008;19(2):197–202.