Class: Vaccines
ATC Class: J07BC02
VA Class: IM100
Brands: Havrix, Twinrix, Vaqta
Introduction
Inactivated virus vaccine.1 39 47 55 115 171 Hepatitis A virus vaccine inactivated contains cell culture-adapted, attenuated hepatitis A virus (HAV) and is used to stimulate active immunity to HAV infection.1 39 47 55 115 171 Commercially available in the US as monovalent vaccines (HepA; Havrix, Vaqta)1 171 and in a fixed-combination vaccine with hepatitis B vaccine (HepA-HepB; Twinrix).186
Uses for Hepatitis A Virus Vaccine Inactivated
Prevention of Hepatitis A Virus (HAV) Infection
Prevention of HAV infection in adults, adolescents, and children ≥1 year of age.1 3 22 110 132 171 192 195 196
Although HAV infection may be asymptomatic or relatively mild in many patients, it can result in substantial morbidity and associated health-care costs and work loss (11–22% of patients require hospitalization) and may be associated with fulminant hepatitis and hepatic failure.38 59 63 75 132 203 Overall HAV case-fatality rate in the US is 0.3–0.6%, but increases to about 2% in those ≥40 years of age.192 203 HAV is highly contagious (especially during the 2 weeks before onset of symptoms).4 16 21 30 32 37 42 50 57 58 85 91 92 94 97 110 120 132 203 The virus is transmitted person-to-person, principally through the fecal-oral route.1 4 16 21 30 32 37 42 50 57 58 85 91 92 94 97 110 120 132 171 203 HAV infection remains one of the most commonly reported vaccine-preventable diseases in travelers.167 192
USPHS Advisory Committee on Immunization Practices (ACIP), AAP, and American Academy of Family Physicians (AAFP) recommend that all children be vaccinated against HAV infection at 1 year of age (i.e., 12 through 23 months of age), unless contraindicated.3 132 192 (See Contraindications under Cautions.)
ACIP, AAP, AAFP, American College of Obstetricians and Gynecologists (ACOG), and American College of Physicians (ACP) also recommend vaccination against HAV for all previously unvaccinated children, adolescents, and adults at high risk of exposure to HAV (see Preexposure Vaccination Against HAV Infection in High-risk Groups under Uses) and for any other unvaccinated individual desiring protection from HAV infection.3 132 192 195 196
For internationally adopted children whose immune status is uncertain, vaccinations can be repeated or serologic tests performed to confirm immunity.60 167 For HepA vaccine, ACIP states that the simplest approach is to revaccinate according to the US recommended immunization schedule if child is ≥12 months of age.60 (See Dosage and Administration.) Alternatively, test for serologic evidence of susceptibility to HAV.60 (See Pre-and Postvaccination Serologic Testing under Cautions.) When a child is being adopted from a country with high or intermediate HAV endemicity, ACIP states that all previously unvaccinated individuals who anticipate close personal contact with the adoptee during the child's initial 60 days in the US (e.g., household members, regular babysitters) should receive routine vaccination with HepA vaccine, with the first dose given as soon as adoption is planned (ideally ≥2 weeks before the child's arrival).209 CDC website () has information regarding which countries have high or intermediate levels of HAV endemicity.167
HepA vaccine will not prevent hepatitis caused by other infectious agents (e.g., hepatitis B virus [HBV], hepatitis C virus [HCV], hepatitis E virus [HEV]).1 171
When vaccination against both HAV and HBV infection is indicated in adults ≥18 years of age, the commercially available fixed-combination vaccine containing HepA vaccine and hepatitis B vaccine (HepA-HepB; Twinrix) can be used.186 192 ACIP, AAP, and AAFP state that use of a combination vaccine generally is preferred over separate injections of the equivalent component vaccines;3 208 considerations should include provider assessment (e.g., number of injections, vaccine availability, likelihood of improved coverage, likelihood of patient return, storage and cost considerations), patient preference, and potential for adverse effects.3 208 However, the HepA-HepB (Twinrix) fixed-combination vaccine should not be used for HAV postexposure prophylaxis.196 (See Use of Fixed Combinations under Cautions.)
Preexposure Vaccination Against HAV Infection in High-risk Groups
Preexposure vaccination in previously unvaccinated children, adolescents, or adults who are or will be at high risk of exposure to HAV or are at high risk of developing fulminant hepatitis and hepatic failure if they become infected with HAV.3 132 167 192 195 196
ACIP, AAP, AAFP, and others recommend preexposure vaccination in previously unvaccinated children ≥12 months of age who reside in states, counties, or communities where the rate of HAV infection is high and in unvaccinated travelers, unvaccinated household or sexual contacts of an individual with confirmed HAV infection, and unvaccinated individuals at risk because of their occupation or high-risk behavior.1 3 45 59 74 76 110 149 171 177 192 195 196
If HepA vaccine cannot be used because it is contraindicated or unavailable and short-term protection against HAV is needed, preexposure passive immunization with IGIM is recommended.26 32 37 40 42 59 74 107 128 132 161 167 196
In states, counties, or communities where the rate of HAV infection is high, ACIP recommends that existing selective preexposure HepA vaccination programs for children 2 through 18 years of age be maintained.192 In such areas, new efforts focused on routine vaccination of all children at 1 year of age should enhance, not replace, ongoing programs directed at a broader population of children.192 In areas without existing selective vaccination programs, catch-up vaccination of unvaccinated children 2 through 18 years of age may be considered.192 Such catch-up vaccination programs may be especially warranted because of rising incidence or ongoing outbreaks of HAV among children or adolescents.192
HIV-infected individuals, especially those with chronic liver disease (including those coinfected with HBV or HCV), should be vaccinated against HAV.197 198 ACIP, AAP, CDC, National Institutes of Health (NIH), Infectious Diseases Society of America (IDSA), Pediatric Infectious Diseases Society, and others recommend that HAV-susceptible, HIV-infected adults, adolescents, and children receive HepA vaccine.197 198 Consider that the vaccine may be less immunogenic in immunocompromised individuals.60 159 187 192 (See Individuals with Altered Immunocompetence under Cautions.)
Travelers to areas with intermediate to high levels of endemic HAV are at risk of exposure to the disease, and ACIP, CDC, WHO, and others recommend preexposure vaccination against HAV for such individuals.13 22 59 63 90 97 110 167 176 192 196 CDC states vaccination against HAV can be considered in individuals traveling to any destination.167 CDC website () has information regarding which countries have high or intermediate levels of HAV endemicity.167 Risk of acquiring HAV while traveling varies with living conditions, length of stay, and incidence of HAV infection in the area visited.167 Consider that many cases of HAV occur in travelers to developing countries with standard tourist itineraries, accommodations, and food consumption behaviors.167 Ideally, the first dose of HepA vaccine should be administered as soon as travel to countries with high or intermediate HAV endemicity is considered.167 196 (See Preexposure Vaccination Against HAV Infection in High-risk Groups under Pediatric Patients and also Adults, in Dosage and Administration.) Alternatively, if the vaccine is contraindicated or cannot be used, passive immunization with a single dose of IGIM may provide protection for up to 3 months.167 196 For optimal protection in travelers at greatest risk for HAV (older adults or individuals with altered immunocompetence, chronic liver disease, or other chronic medical condition) who plan to depart in <2 weeks, a dose of IGIM should be given concomitantly with the initial dose of HepA vaccine (at a different site).167 ACIP states that the fixed-combination vaccine containing HepA vaccine and HepB vaccine (HepA-HepB; Twinrix) should not be used for preexposure vaccination in travelers who will depart within 2 weeks.192 196 (See Use of Fixed Combinations under Cautions.)
Household and sexual contacts of individuals with confirmed HAV infection are at increased risk of exposure to HAV.21 192 Sexually active male adolescents and adults who have sex with men (homosexual, bisexual) should be vaccinated against HAV.2 110 179 192 Primary-care clinicians and those in specialty medical settings should offer the vaccine to such individuals; strategies to increase coverage (e.g., use of standing orders) should be considered.192
Individuals who illicitly use injectable or noninjectable drugs may be at increased risk of exposure to HAV infection and should be vaccinated against HAV.63 74 76 97 192 Clinicians should obtain a complete history to identify individuals who might benefit from HepA vaccination (e.g., those who use illicit drugs or who are at increased risk for such drug use).192 Clinicians should consider implementing strategies to increase vaccine coverage in these patients (e.g., use of standing orders).192
Individuals with hemophilia or other congenital bleeding disorders who are HAV-seronegative should be vaccinated against HAV.18 61 195 Improved donor screening, more effective viral-inactivation procedures, and/or purification or filtration procedures have reduced, but not completely eliminated, the risk of pathogen transmission from plasma-derived clotting factors.192 Therefore, recipients of blood products (e.g., whole blood, packed RBCs, plasma) and plasma-derived preparations (e.g., albumin human, antihemophilic factor [human], anti-inhibitor coagulant complex, factor IX [human], factor IX complex) may be at increased risk of HAV infection.18 61 64 65 66 67 68 70 100 101 102 138 165 168 169 192
Workers handling HAV-infected nonhuman primates and workers in contact with live HAV in a research laboratory setting should be vaccinated against HAV.67 99 108 110 192 Routine vaccination against HAV is not currently recommended for other occupational groups in the US.192
Individuals with chronic liver disease and those who are awaiting or have undergone liver transplantation should be vaccinated against HAV.132 192 Although individuals with chronic liver disease are not at increased risk of acquiring HAV infection, such individuals are at increased risk of severe consequences of HAV infection, including fatal fulminant hepatitis and hepatic failure.16 74 103 110 192
Some clinicians recommend that individuals with HBV or HCV infection, autoimmune hepatitis, or primary biliary cirrhosis be vaccinated against HAV.132 177 ACIP states that current data do not support routine vaccination of individuals who have chronic HBV or HCV infection but do not have evidence of chronic liver disease.192
Food handlers and restaurant employees may be vaccinated against HAV.84 177 192 Vaccination may be considered in restaurant employees in areas where state and local health authorities or private employers have determined that such vaccination is indicated to decrease the frequency of HAV evaluations of food handlers and decrease the need for HAV postexposure prophylaxis in restaurant patrons.84 177 192 Under these circumstances, a record of HepA vaccination should be provided to vaccinated food handlers, those not vaccinated should be informed of the signs and symptoms of HAV infection, and all food handlers should be instructed on food preparation practices that reduce risk of fecal contamination.192 Routine use of HepA vaccine in all food handlers is not economically feasible from a societal or food industry perspective.84 177 192 Occasionally, vaccination of food handlers may be considered during a community outbreak.110 177 192
Incarcerated adolescents in correctional facilities located in states with existing HepA vaccination programs for adolescents should receive HepA vaccine.132 Because of the likelihood that adolescents in juvenile correctional systems have indications for the vaccine, other correctional facilities also should consider routine HepA vaccination of all adolescents under their care.132 Test those with signs or symptoms of hepatitis for acute HAV, HBV, and HCV infection.132 Report those with HAV to the local health department and give appropriate postexposure prophylaxis with HepA vaccine to susceptible exposed residents.132
If a community-wide outbreak of HAV occurs, accelerated HepA vaccination programs should be considered.192 A decision to initiate an outbreak-control vaccination program should take into account the feasibility of rapidly vaccinating the target population of children, adolescents, or young adults, and the costs associated with such a program.192 Routine vaccination of children in affected communities should continue in order to maintain high levels of immunity and prevent future epidemics.192
HAV outbreaks in child-care centers have decreased considerably since the implementation of routine childhood immunization against HAV and further decreases are expected.192 ACIP does not recommend routine preexposure vaccination with HepA vaccine for personnel in child-care centers.192 However, HAV postexposure prophylaxis may be indicated if HAV is reported in attendees or staff.196 (See Postexposure Prophylaxis of HAV Infection under Uses.)
ACIP does not recommend routine preexposure vaccination with HepA vaccine in hospitals or schools and institutions for the developmentally disabled because the frequency of outbreaks in these institutions is not high enough to warrant such recommendations.192 Outbreaks involving student-to-student transmission in primary and secondary schools are rare in developed countries, but outbreaks have been documented;32 132 161 192 in developing countries, outbreaks among children in primary schools are more common.7 151 161 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, HAV postexposure prophylaxis should be administered to individuals who have close contact with index patients.107 132 192 196 (See Postexposure Prophylaxis of HAV Infection under Uses.)
ACIP and Hospital Infection Control Practices Advisory Committee (HICPAC) state that routine preexposure vaccination with HepA vaccine or routine use of HAV postexposure prophylaxis in health-care personnel providing care to patients with HAV infection is not indicated.178 192 Instead, hygienic practices should be emphasized and health-care personnel should be made aware of the risk of exposure to HAV and precautions regarding direct contact with potentially infective materials.178 192 In documented outbreaks of HAV infection, HAV postexposure prophylaxis may be indicated in health-care workers and others who have close contact with the infected individuals.178 (See Postexposure Prophylaxis of HAV Infection under Uses.) The usefulness of HepA vaccine in controlling outbreaks in health-care settings has not been investigated.178
Postexposure Prophylaxis of HAV Infection
Postexposure prophylaxis of HAV† in susceptible individuals with recent (within 2 weeks) exposure to HAV.132 178 179 192 196
The choice of active immunization with HepA vaccine and/or passive immunization with IGIM for postexposure prophylaxis should take into account the magnitude of risk associated with the exposure and characteristics of the patient that may be associated with more severe manifestations of HAV (e.g., older age, chronic liver disease).132 178 179 192 196
Although IGIM was traditionally the recommended regimen for HAV postexposure prophylaxis since it is 80–90% effective if administered within 2 weeks of exposure,196 there is some evidence that monovalent HepA vaccine administered within 2 weeks of exposure may be as effective as IGIM in healthy individuals 1–40 years of age.196 199 The vaccine also offers certain advantages over IGIM (e.g., induces active immunity and longer protection, more readily available, easier to administer, greater patient acceptance).196 199
For HAV postexposure prophylaxis in healthy individuals 12 months to 40 years of age, ACIP prefers use of monovalent HepA vaccine.196 In adults >40 years of age, ACIP prefers use of IGIM since data not available to date regarding efficacy of the vaccine for postexposure prophylaxis in this age group and these individuals are at risk of more severe manifestations of HAV; the vaccine can be used if IGIM cannot be obtained.196 IGIM should be used for HAV postexposure prophylaxis in children <12 months of age, immunocompromised individuals, individuals with chronic liver disease, and whenever the vaccine is contraindicated.196
In those individuals in whom IGIM is preferred for HAV postexposure prophylaxis, a dose of HepA vaccine should be given simultaneously (using different syringes and different injection sites) if the vaccine is indicated for other reasons (e.g., catch-up vaccination, preexposure vaccination in high-risk groups) and is not contraindicated.196 If a dose of HepA vaccine is used with or without IGIM for HAV postexposure prophylaxis, a second (booster) dose of the vaccine should be administered according to the usually recommended schedule to ensure long-term protection.192 196 (See Dosage under Dosage and Administration.)
Monovalent HepA vaccine (Havrix, Vaqta) should be used when active immunization is indicated for HAV postexposure prophylaxis.196 Data not available to date regarding efficacy of the fixed-combination vaccine containing HepA vaccine and HepB vaccine (HepA-HepB; Twinrix) for postexposure prophylaxis.196 (See Use of Fixed Combinations under Cautions.)
If HAV postexposure prophylaxis is indicated, administer as soon as possible (within 2 weeks of exposure).192 196 Data not available regarding efficacy of HAV postexposure prophylaxis administered >2 weeks after exposure.196
HAV postexposure prophylaxis is indicated in all previously unvaccinated individuals who have had household or sexual contact (within the last 2 weeks) with an individual with serologically confirmed HAV.196 Also consider HAV postexposure prophylaxis for individuals exposed (within the last 2 weeks) through other types of ongoing, close personal contact (e.g., regular babysitting).196
Contacts who have shared illicit drugs (within the last 2 weeks) with an individual with serologically confirmed HAV should receive HAV postexposure prophylaxis.196
Administer HAV postexposure prophylaxis to all previously unvaccinated staff and attendees of child-care centers or homes if ≥1 case of HAV is recognized in children or employees or if HAV is recognized in ≥2 households of center attendees (within the last 2 weeks).196 In centers that do not provide care to children who wear diapers, HAV postexposure prophylaxis is indicated only in classroom contacts of the index patient.196 If an outbreak occurs (i.e., HAV in ≥3 families), HAV postexposure prophylaxis should also be considered for members of households that have diapered children attending the center.196
If HAV is diagnosed in a food handler, ACIP recommends HAV postexposure prophylaxis (within 2 weeks) for other food handlers at the same establishment.196 Because common-source transmission to patrons is unlikely, HAV postexposure prophylaxis is not usually indicated for restaurant patrons, but may be considered if the food handler directly handled uncooked or cooked food and had diarrhea or poor hygienic practices and if patrons can be identified and treated within 2 weeks of exposure.196 Settings where repeated HAV exposure might have occurred (e.g., institutional cafeterias) warrant stronger consideration of postexposure prophylaxis for patrons.196
When an individual with HAV is admitted to a hospital, health-care personnel do not need to receive routine HAV postexposure prophylaxis; careful hygienic practices should be emphasized in such situations.196
If an epidemiologic investigation indicates that HAV transmission has occurred among students in a school or among hospital patients and/or hospital staff, ACIP recommends HAV postexposure prophylaxis in individuals who have close contact with index patients.196
Routine HAV postexposure prophylaxis is not indicated when a single HAV case occurs in an elementary or secondary school or an office or other work setting and the source case is outside the school or work setting.196
HAV postexposure prophylaxis is not usually indicated after a common-source HAV outbreak if cases have begun to occur because the 2-week period when such prophylaxis is known to be effective will have been exceeded.196
Hepatitis A Virus Vaccine Inactivated Dosage and Administration
Administration
IM Injection
Administer monovalent HepA vaccine (Havrix, Vaqta) by IM injection.1 171
Administer fixed-combination vaccine containing HepA vaccine and HepB vaccine (HepA-HepB; Twinrix) by IM injection.186
Do not administer IV, intradermally, or sub-Q.1 171
Shake vaccine well immediately prior to administration to provide a uniform, slightly turbid, white, suspension.1 171 186 200 Discard vaccine if there are cracks in the vial or syringe or if it contains particulates, appears discolored, or cannot be resuspended with thorough agitation.1 171 200
Do not dilute.1 186 Do not mix with any other vaccine or solution.1 60 171 186
To ensure delivery into muscle, IM injections should be made at a 90° angle to the skin60 using a needle length appropriate for the individual's age and body mass, thickness of adipose tissue and muscle at the injection site, and injection technique.60 206 207 Consider anatomic variability, especially in the deltoid; use clinical judgment to avoid inadvertent underpenetration or overpenetration of muscle.206 207
For adults, administer IM into the deltoid muscle.1 60 For children 1–2 years of age, IM injections should preferably be administered into the anterolateral thigh;1 60 deltoid muscle is an alternative if muscle mass is adequate.60 For children and adolescents 3–18 years of age, deltoid muscle is preferred,1 60 although anterolateral thigh is an alternative.60
Generally do not administer vaccines into buttock muscle in children because of potential for injection-associated injury to sciatic nerve.60 In addition, studies in adults indicate suboptimal immunologic response may occur if HepA vaccine is injected into gluteal muscle.1 60
Although some experts state that aspiration (i.e., pulling back on the syringe plunger after needle insertion and before injection) can be performed to ensure that a blood vessel has not been entered, ACIP and AAP state this procedure is not required because large blood vessels are not present at recommended IM injection sites.60 132
Since syncope may occur following vaccination, observe vaccinees for approximately 15 minutes after the dose.60 Syncope occurs most frequently in adolescents and young adults.60 If syncope occurs, observe patient until symptoms resolve.60
May be given simultaneously with IGIM (using different syringes and different injection sites) when passive immunization is considered necessary in addition to active immunization with the vaccine (e.g., in travelers who will depart within 2 weeks).1 60 132 171 192 196 (See Interactions.)
May be given simultaneously with other age-appropriate vaccines during the same health-care visit (using different syringes and different injection sites).60 132 192 (See Interactions.)
When multiple vaccines are administered during a single health-care visit, each vaccine should be given with a different syringe and at different injection sites.60 Separate injection sites by at least 1 inch (if anatomically feasible) to allow appropriate attribution of any local adverse effects that may occur.60 If multiple vaccines must be given into a single limb, the deltoid may be used in older children and adults, but the thigh is preferred in younger children.60
Dosage
Dose and dosing schedule vary according to the individual’s age and specific vaccine administered.1 171 186 Follow dosage recommendations for the specific preparation used.192
Whenever possible, the HepA monovalent vaccine used for the initial dose should be used for subsequent doses in the same individual.192 However, ACIP and AAP state that the currently available monovalent formulations may be considered interchangeable.60 132 192
For both monovalent vaccines, the minimum interval between the first and second dose is 6 months.1 3 171 192 Dosage for the second (booster) dose should be based on the individual's age at the time the second dose is given.203 Although only limited data are available regarding the immune response to delayed administration of the second dose,192 some experts state it is not necessary to repeat the first dose if the interval between the first and second dose extends beyond 18 months.203
When vaccination against both HAV and HBV infection is indicated in adults ≥18 years of age, the commercially available fixed-combination vaccine containing HepA vaccine and HepB vaccine (HepA-HepB; Twinrix) can be used.186 192
Pediatric Patients
Prevention of Hepatitis A Virus (HAV) Infection
Children and Adolescents 12 Months through 18 Years of Age (Havrix)
IM
Primary immunization consists of 2 doses given 6–12 months apart.1 3 192
Give initial dose of 720 units.1 132 192 Give second (booster) dose of 720 units at 6–12 months after initial dose.1 192
ACIP, AAP, and AAFP recommend that the initial dose be given routinely to all children at 1 year of age (i.e., 12 through 23 months of age) and that the second dose be given at least 6 months after the initial dose.3
Children not fully vaccinated by 2 years of age can be vaccinated at subsequent health-care visits.3 ACIP recommends that catch-up vaccination be considered for children 2 through 18 years of age in areas without existing selective preexposure HepA vaccination programs.192
If a different HepA vaccine (e.g., Vaqta) was used for the initial dose, a booster dose of Havrix may be given 6–18 months after the initial dose of the other vaccine.192 However, whenever possible, the formulation chosen for the initial dose should be used for the booster dose in the same individual.192
Duration of immunity and need for subsequent doses after the initial dose and additional (booster) dose not fully determined.1 2 6 7 23 33 41 46 49 74 76 77 84 145 149 150 155 192 (See Duration of Immunity under Cautions.) Subsequent booster doses not recommended.192
Children and Adolescents 12 Months through 18 Years of Age (Vaqta)
IM
Primary immunization consists of 2 doses given 6–18 months apart.3 171 192 Use pediatric/adolescent formulation containing 25 units/0.5 mL.171
Give initial dose of 25 units.132 171 192 Give second (booster) dose of 25 units 6–18 months after initial dose.171
ACIP, AAP, and AAFP recommend that the initial dose be given routinely to all children at 1 year of age (i.e., 12 through 23 months of age) and that the second dose be given at least 6 months after the initial dose.3
Children not fully vaccinated by 2 years of age can be vaccinated at subsequent health-care visits.3 ACIP recommends that catch-up vaccination be considered for children 2 through 18 years of age in areas without existing selective preexposure HepA vaccination programs.192
If a different HepA vaccine (e.g., Havrix) was used for the initial dose, a booster dose of Vaqta may be given 6–12 months after the initial dose of the other vaccine.171 192 However, whenever possible, the formulation chosen for the initial dose should be used for the booster dose in the same individual.192
Duration of protection and need for subsequent doses after the initial dose and second (booster) dose not fully determined.2 6 7 23 33 41 46 49 74 76 77 84 145 149 150 155 171 192 (See Duration of Immunity under Cautions.) Subsequent booster doses not recommended.192
Preexposure Vaccination Against HAV Infection in High-risk Groups
Children and Adolescents 12 Months through 18 Years of Age (Havrix or Vaqta)
IM
Primary immunization with the usually recommended age-appropriate initial and second (booster) doses before an expected exposure to HAV ensures the highest level of protection.1 148 158 171 192 196 (See Prevention of Hepatitis A Virus (HAV) Infection under Dosage and Administration.) Those who have received at least 1 dose given 1 month prior to an exposure probably will be protected.167 192 196
For individuals who plan to travel or work in areas with intermediate to high levels of endemic HAV (see Preexposure Vaccination Against HAV Infection in High-risk Groups under Uses), give first vaccine dose as soon as travel is considered.167 196 For most healthy children, a single dose will provide adequate protection regardless of the scheduled departure date.167 196 To ensure protection in immunocompromised individuals or those with chronic liver disease or other chronic medical conditions who plan to depart within 2 weeks, give initial vaccine dose and simultaneously (using a different syringe and different injection site) give a single dose of IGIM (0.02 mL/kg).167 196
Postexposure Prophylaxis of HAV Infection†
Children and Adolescents 12 Months through 18 Years of Age (Havrix or Vaqta)
IM
Give an age-appropriate dose of vaccine alone or in conjunction with a dose of IGIM (0.02 mL/kg) as soon as possible.196 Efficacy of HAV postexposure prophylaxis not established if given >2 weeks after exposure.196 (See Postexposure Prophylaxis of HAV Infection under Uses.)
In previously unvaccinated individuals, give primary immunization with the usually recommended age-appropriate initial and second (booster) doses of the vaccine.1 107 111 128 171 192 (See Prevention of Hepatitis A Virus (HAV) Infection under Dosage and Administration.) The first vaccine dose can be administered simultaneously with IGIM (using different syringes and different injection sites).1 107 111 128 171 192
Individuals who have received at least 1 vaccine dose at least 1 month prior to the current HAV exposure do not need to receive postexposure prophylaxis with IGIM.179 192
Adults
Prevention of Hepatitis A Virus (HAV) Infection
Adults ≥19 Years of Age (Havrix)
IM
Primary immunization consists of 2 doses given 6–12 months apart.1 192
Give initial dose of 1440 units.1 171 192 Give second (booster) dose of 1440 units 6–12 months after initial dose.1 192
If a different HepA vaccine (e.g., Vaqta) was used for the initial dose, a booster dose of Havrix may be given 6–12 months after the initial dose of the other vaccine.192 However, whenever possible, the formulation chosen for the initial dose should be used for the booster dose in the same individual.132 192
Duration of protection and need for subsequent doses after the initial dose and second (booster) dose not fully determined.1 2 6 7 23 33 41 46 49 74 76 77 84 145 149 150 155
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