Prevention of Hepatitis A Through Active or Passive Immunization

Recommendations For Use of Hepatitis A Vaccine and Immune Globulin

Preexposure Protection Against Hepatitis A Virus Infection

Hepatitis A vaccination provides preexposure protection from HAV infection in children and adults. Hepatitis A vaccination is recommended for persons who are at increased risk for infection and for any person wishing to obtain immunity.

Populations at Increased Risk for HAV Infection or the Adverse Consequences of Infection

• Persons traveling to or working in countries that have high or intermediate endemicity of infection. All susceptible persons traveling to or working in countries that have high or intermediate HAV endemicity (Figure 3) should be vaccinated or receive IG before departure (Tables 3 and 4). Hepatitis A vaccination at the age-appropriate dose is preferred (Table 4) for children, adolescents, and adults who plan frequent travel or who reside for long periods in a high-risk area. IG is recommended for travelers <2 years of age because the vaccine is currently not licensed for use in this age group. Prevaccination testing should be considered for older travelers or for younger persons in certain population groups (See pre-vaccination serologic testing for susceptibility).

  Travelers to North America (except Mexico and Central America), western Europe, Japan, Australia, or New Zealand are at no greater risk for infection than in the United States. Data are not available regarding the risk for hepatitis A for persons traveling to developed areas of the Caribbean, although vaccine or IG should be considered if travel to areas that have questionable sanitation is anticipated.

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  Travelers who are administered vaccine should receive the first vaccine dose at least 4 weeks before travel. Persons can be assumed to be protected by 4 weeks after receiving the first vaccine dose, although a second dose 6-12 months later is necessary for long-term protection. Because protection may not be complete until 4 weeks after vaccination, persons traveling to a high-risk area <4 weeks after the initial dose also should be administered IG (0.02 mL/kg), but at a different anatomic injection site.

  Travelers who are allergic to a vaccine component or who elect not to receive vaccine should receive a single dose of IG (0.02 ML/KG), which provides effective protection against hepatitis A for up to 3 months (Table 3). Travelers whose travel period exceeds 2 months should be administered IG at 0.06 ML/KG; administration must be repeated if the travel period exceeds 5 months (Table 3).

• Children in communities that have high rates of hepatitis A and periodic hepatitis A outbreaks. Children living in communities that have high rates of hepatitis A (Table 2) should be routinely vaccinated beginning at >2 years of age. In addition, to effectively prevent epidemics of Hepatitis A in these communities, vaccination of previously unvaccinated older children is recommended within 5 years of initiation of routine childhood vaccination programs. Although rates differ among areas, available data indicate that reasonable cut-off age in many areas is 10-15 years of age because older persons are often already immune and vaccination of younger children will indirectly protect older persons who may be susceptible. Vaccination of children before they enter school should receive highest priority, followed by vaccination of older children who have not been vaccinated. Pre-vaccination serologic testing is not indicated for vaccination of previously unvaccinated children in this setting.

• Men who have sex with men. Sexually active men who have sex with men (both adolescents and adults) should be vaccinated. Prevaccination testing is not indicated for the vaccination of adolescents in this group, yet may be warranted for adults, especially those >40 years of age.

• Illegal-drug users. Vaccination is recommended for injecting and noninjecting illegal-drug users if local epidemiologic and surveillance data indicate current or past outbreaks among persons with such risk behaviors. Prevaccination testing is not indicated for the vaccination of adolescent illegal-drug users but may be warranted for adults, especially those >40 years of age, who practice such behaviors.

• Persons who have occupational risk for infection. Persons who work with HAV-infected primates or with HAV in a research laboratory setting should be vaccinated. No other groups have been shown to be at increased risk for HAV infection because of occupational exposure.

• Persons who have chronic liver disease. Susceptible persons who have chronic liver disease should be vaccinated. Persons who are either awaiting or have received liver transplants also should be vaccinated.

• Persons who have clotting-factor disorders. Susceptible persons who are administered clotting-factor concentrates, especially solvent-detergent-treated preparations, should be administered hepatitis A vaccine.

• Other groups. Persons who work as food handlers can contract hepatitis A and potentially transmit HAV to others. To decrease the frequency of evaluations of food handlers with hepatitis A and the need for postexposure prophylaxis of patrons, consideration may be given to vaccination of employees who work in areas where state and local health authorities or private employers determine that such vaccination is cost effective.

Hepatitis A Vaccination in Outbreak Settings

• Outbreaks in communities that have high rates of hepatitis A. Routine vaccination of children 2 years of age and accelerated vaccination of older children who have not been previously vaccinated should be implemented to control an ongoing outbreak. The upper age for vaccination of older, previously unvaccinated children should be determined by using age-specific rates of hepatitis A (or sero-prevalence data, if available). In communities that have begun a vaccination program (i.e., routine vaccination of children 2 years of age and vaccination of older children who have not been previously vaccinated), the vaccination component directed toward older children who have not been previously vaccinated should be accelerated so that at least 70% coverage is achieved as quickly as possible.

• Outbreaks in communities that have intermediate rates of hepatitis A. Hepatitis A vaccination of children or adolescents may have the potential to control hepatitis A outbreaks in these communities (Table 2). These communities often are located in large cities or counties; thus, widespread vaccination may not be feasible. Targeting vaccination to subpopulations or groups that have the highest rates of disease may be more feasible; however, the effectiveness of using vaccine in these settings and under these conditions has not been determined.

  To determine candidate groups for vaccination, local surveillance and epidemiologic data should be used to define populations (e.g., age groups or risk groups) or areas within the community (e.g., census tracts) that have the highest rates of disease. Factors to consider in deciding whether to vaccinate persons in a certain group include a) the feasibility of rapidly vaccinating the target populations of children, adolescents, or young adults; b) program cost; and c) the ability to sustain ongoing vaccination of young children to maintain high levels of immunity and prevent future epidemics.

  In some communities, day care centers play a role in sustaining communitywide outbreaks. In this situation, consideration should be given to adding hepatitis A vaccine to the immunoprophylaxis regimen for children and staff in the involved center or centers (see Postexposure Prophylaxis with Immune Globulin) and, possibly, vaccinating children in day care centers where cases of hepatitis A have not been detected. Because experience when using hepatitis A vaccine to control hepatitis A in communities that have intermediate rates of hepatitis A is limited, evaluation of the effectiveness of vaccination should be an essential element of programs in these settings.

• Outbreaks in other settings. The frequency of outbreaks in day care centers, hospitals, institutions (e.g., institutions for the developmentally disabled and prisons), and schools is not high enough to warrant routine hepatitis A vaccination of persons in these settings. When outbreaks are recognized in day care centers, aggressive use of IG is effective in limiting transmission to employees and families of attendees (see Postexposure Prophylaxis with Immune Globulin). When outbreaks occur in hospitals, institutions, and schools, use of IG in persons in close contact with infected patients or students who have hepatitis A is recommended (see Postexposure Prophylaxis with Immune Globulin). The role of hepatitis A vaccine in controlling outbreaks in these settings has not been investigated.

Postexposure Prophylaxis with Immune Globulin

Persons who have been recently exposed to HAV and who have not previously been administered hepatitis A vaccine should be administered a single IM dose of IG (0.02 mL/kg) as soon as possible, but not >2 weeks after exposure. Persons who have been administered one dose of hepatitis A vaccine at least 1 month before exposure to HAV do not need IG.

Because hepatitis A cannot be reliably diagnosed on clinical presentation alone, serologic confirmation of HAV infection in index patients by IgM anti-HAV testing is recommended before postexposure treatment of contacts. Screening of contacts for immunity before giving IG is not recommended because screening is more costly than IG and would delay its administration.

IG should be administered to previously unvaccinated persons in the following situations. If hepatitis A vaccine is recommended for a person being given IG, it may be administered simultaneously with IG at a separate anatomic injection site.

• Close personal contact. IG should be administered to all household and sexual contacts of persons who have serologically confirmed hepatitis A.

• Day care centers. IG should be administered to all staff and attendees of day care centers or homes if a) one or more cases of hepatitis A are recognized in children or employees or b) cases are recognized in two or more households of center attendees. In centers that do not provide care to children who wear diapers, IG need be given only to classroom contacts of an index case-patient. When an out-break occurs (i.e., hepatitis cases in three or more families), IG also should be considered for members of households that have children (center attendees) in diapers.

• Common-source exposure. If a food handler is diagnosed with hepatitis A, IG should be administered to other food handlers at the same location. Administration of hepatitis A vaccine to these other food handlers might also be considered. Because common-source transmission to patrons is unlikely, IG administration to patrons is usually not recommended but may be considered if a) during the time when the food handler was likely to be infectious, the food handler both directly handled uncooked foods or foods after cooking and had diarrhea or poor hygienic practices and b) patrons can be identified and treated within 2 weeks after the exposure. In settings where repeated exposures to HAV may have occurred (e.g., institutional cafeterias), stronger consideration of IG use may be warranted. In the event of a common-source outbreak, IG should not be administered to exposed persons after cases have begun to occur because the 2-week period during which IG is effective will have been exceeded.

• Schools, hospitals, and work settings. IG is not routinely indicated when a single case occurs in an elementary or secondary school, an office, or in other work settings, and the source of infection is outside the school or work setting. Similarly, when a person who has hepatitis A is admitted to a hospital, staff should not routinely be administered IG; instead, careful hygienic practices should be emphasized. IG should be administered to persons 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 in a hospital.
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