hepatitis b: global epidemiology and prevention strategies
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Hepatitis B: Global Epidemiology and Prevention Strategies. Components of Strategies to Prevent HBV Transmission. Hepatitis B immunization Universal infant immunization Prevent perinatal transmission Catch-up immunization Prevent nosocomial HBV transmission. - PowerPoint PPT PresentationTRANSCRIPT
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Hepatitis B: Global Epidemiology and
Prevention Strategies
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Components of Strategies to Components of Strategies to Prevent HBV TransmissionPrevent HBV Transmission
• Hepatitis B immunization
– Universal infant immunization
– Prevent perinatal transmission
– Catch-up immunization
• Prevent nosocomial HBV transmissionPrevent nosocomial HBV transmission
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Hepatitis B Virus Infection Hepatitis B Virus Infection Global Disease BurdenGlobal Disease Burden
• 2,000 million have markers of 2,000 million have markers of current or past infectioncurrent or past infection
• 350 million have chronic infection350 million have chronic infection– 15%-25% will die from chronic liver
disease (liver cancer and cirrhosis)– about 750,000 deaths per year
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Outcome of HBV Infection Depends on Age of Infection
Young children• <10% get sick when first infected• chronic infection:
•80-90% at age < 1 year•30-50% at age 1-4 years
• 25% die from liver cancer/cirrhosis
Adults– 30-50% get sick when first infected– 2-6% develop chronic infection– 15% die from liver cancer/cirrhosis
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Geographic Distribution of Chronic HBV Infection
HBsAg Prevalence
8% - High 2-7% - Intermediate <2% - Low
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• High (8%): 45% of global population– lifetime risk of infection >60%– early childhood infections common
• Intermediate (2%-7%): 43% of global population– lifetime risk of infection 20%-60%– infections occur in all age groups
• Low (<2%): 12% of global population– lifetime risk of infection <20%– most infections occur in adult risk groups
Global Patterns of Chronic HBV Infection
Global Patterns of Chronic HBV Infection
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Routes of HBV TransmissionRoutes of HBV Transmission
Age Group Route(s) of Infection
Newborn •mother to infant
•child to child •unsafe injections
Childhood
Adolescent/Adult
•sexual contact•injecting drug use•unsafe injections
EndemicityLow Int High
++
++++
+ + +
++
++ -
++++ +++ -
++
++
+++ +
++ ++ +/-
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Age of acquisition of Age of acquisition of chronic HBV infections by chronic HBV infections by
endemicityendemicityLow Intermediate High
Perinatal Childhood Adolescent/Adult
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Hepatitis B Immunization Hepatitis B Immunization ProgramsPrograms
ObjectiveObjectivePrevent chronic HBV infections
•prevent chronic liver disease•reduce the reservoir for transmission of new infections
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Components of Strategies to Components of Strategies to Prevent HBV TransmissionPrevent HBV Transmission
• Hepatitis B immunization
– Universal infant immunization
– Prevent perinatal transmission
– Catch-up immunization
• Prevent nosocomial HBV transmissionPrevent nosocomial HBV transmission
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Hepatitis B Vaccination TargetsHepatitis B Vaccination Targets45th World Health Assembly, 199245th World Health Assembly, 1992
Integrate hepatitis B vaccine into national Integrate hepatitis B vaccine into national childhood vaccination programschildhood vaccination programs
•By 1995 in countries with HBsAg prevalence 8%
•By 1997 in all countries
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Global Status of Hepatitis B Immunization Policyas of January 2001
Implemented (129)
Not implemented (85)
February 20, 2001
The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.
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Hep B Vaccine Implementation in GFCV-Eligible Countries*
Not yet eligible - DTP3<50% (N=16)
Approved (N=24)
Application pending (N=16)
Implemented (N=18)
*4th tranche-June 2001
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Impact of Hepatitis B Immunization Impact of Hepatitis B Immunization
Reduces prevalence of chronic HBV infection in immunized cohorts
<1% in areas with low rate of perinatal transmission
<2% in areas with high rate of perinatal transmission
Reduces infection "pressure"
Unvaccinated persons with chronic infection lose HBeAg and become less infectious
Results in greater than expected impact on transmission
Reduces liver cancer
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Effect of Routine Infant Immunization on the Effect of Routine Infant Immunization on the Prevalence of Chronic HBV InfectionPrevalence of Chronic HBV Infection
Chronic HBV infection
Study Year No.Tested
Age(yrs)
Vaccine Coverage
BeforeProgram
After Program
Alaska 1995 268 1-10 96% 16% 0%
Taiwan 1994 424 7-10 73% 10% 1.1%
Samoa 1996 435 7-8 87% 7% 0.5%
Lombok 1994 2519 4 > 90% 6.2% 1.9%
Saipan 1994 200 3-4 94% 9% 0.5%
Ponape 1994 364 3-4 82% NA 1.0%
Micronesia 1992 544 2 40% 12% 3.0%
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Age of Acquisition of Chronic Age of Acquisition of Chronic HBV Infections in High Endemic HBV Infections in High Endemic
CountriesCountries
Perinatal 10-30
Young children 65-80
Adolescents/Adults <5
% of Chronic Infections
Age of Acquisition
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Strategies to Prevent Strategies to Prevent Perinatal HBV Transmission (1)Perinatal HBV Transmission (1)
Selective Immunoprophylaxis • Screen pregnant women for HBsAg• Give prophylaxis to infants of HBsAg+ mothers
Pros– prophylaxis targeted to infants that need it– can administer both HBIG/HepB vaccine Issues– Requires extensive resources to screen pregnant
women/track infants of HBsAg+ mothers– Few successful programmes
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Strategies to Prevent Strategies to Prevent Perinatal HBV Transmission (2)Perinatal HBV Transmission (2)
Integrate as Component of Routine Infant VaccinationIntegrate as Component of Routine Infant Vaccination
• Vaccinate all infants beginning at birth
Pros
– No need to screen pregnant women
– Very feasible to implement if a high proportion of infants are born in health care facilities
Issues
– Need to assure effective HepB vaccine delivery for all infants
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Priority of Giving a Birth Dose
Issues to consider
• Contribution of perinatal transmission to overall hepatitis B disease burden
• Feasibility of delivering the first dose at birth
– Currently, most feasible in hospitals
– With availability of Uniject, it may be feasible to give HepB vaccine to infants delivered at home
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Priority of Perinatal Hepatitis B PreventionHigh proportion of chronic infections acquired perinatally (e.g.,
SE Asia)
• A birth dose should be given when feasible (e.g., in birthing hospitals)
• Efforts should be made to administer HepB vaccine to infants who deliver at home
Low proportion of chronic infections acquired perinatally (e.g., Africa)
• A birth dose may be considered after evaluating disease burden, cost-effectiveness, and feasibility
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Priority of Catch-up Immunization
High endemicity of HBV infection
• Most chronic infections acquired before age 5 years
• Immunizing infants will rapidly reduce transmission
• Catch-up immunization not generally needed
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Priority of Catch-up Immunization II
Lower endemicity of HBV infection
• May be large disease burden from infections acquired in older age groups
• Immunizing infants alone may not substantially lower disease incidence for decades
• Catch-up immunization may be desirable:
– single-age cohorts (e.g., routine adolescent immunization)
– high risk groups (e.g., MSM, IDUs, persons w/STDs)• STD clinics, correctional facilities, drug treatment
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Components of Strategies to Components of Strategies to Prevent HBV TransmissionPrevent HBV Transmission
• Hepatitis B immunization
– Universal infant immunization
– Prevent perinatal transmission
– Catch-up immunization
• Prevent nosocomial HBV transmissionPrevent nosocomial HBV transmission
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HBV Transmission in Healthcare HBV Transmission in Healthcare SettingsSettings
ProviderProvider
ProviderProviderPatientPatient
•Unsafe injection practices•Reuse of contaminated medical equipment •Blood transfusion
PatientPatient
PatientPatient
PatientPatient
•Needlestick/sharps injuries
•Invasive surgical procedures
•Use safe injection practices•Use sterile equipment •Screen blood supply
•Use standard precautions•Vaccinate HCW
•Use standard precautions