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Hepatitis B: Global Epidemiology and Prevention Strategies

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.

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Hepatitis B: Global Epidemiology and Prevention Strategies

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  1. Hepatitis B: Global Epidemiology and Prevention Strategies

  2. Components of Strategies to Prevent HBV Transmission • Hepatitis B immunization • Universal infant immunization • Prevent perinatal transmission • Catch-up immunization • Prevent nosocomial HBV transmission

  3. Hepatitis B Virus Infection Global Disease Burden • 2,000 million have markers of current or past infection • 350 million have chronic infection • 15%-25% will die from chronic liver disease (liver cancer and cirrhosis) • about 750,000 deaths per year

  4. 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

  5. Geographic Distribution of Chronic HBV Infection HBsAg Prevalence 8% - High 2-7% - Intermediate <2% - Low

  6. Global Patterns of Chronic HBV Infection • 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

  7. Routes of HBV Transmission Endemicity Low Int High Age Group Route(s) of Infection • mother to infant Newborn ++ ++ ++ • child to child • unsafe injections Childhood ++ - +++ + ++++ ++ • sexual contact • injecting drug use • unsafe injections Adolescent/ Adult + + + ++++ +++ - ++ ++ +/-

  8. Age of acquisition of chronic HBV infections by endemicity Intermediate High Low Perinatal Childhood Adolescent/Adult

  9. Hepatitis B Immunization ProgramsObjective Prevent chronic HBV infections • prevent chronic liver disease • reduce the reservoir for transmission of new infections

  10. Components of Strategies to Prevent HBV Transmission • Hepatitis B immunization • Universal infant immunization • Prevent perinatal transmission • Catch-up immunization • Prevent nosocomial HBV transmission

  11. Hepatitis B Vaccination Targets 45th World Health Assembly, 1992 • Integrate hepatitis B vaccine into national • childhood vaccination programs • By 1995 in countries with HBsAg prevalence 8% • By 1997 in all countries

  12. Global Status of Hepatitis B Immunization Policy as of January 2001 Implemented (129) 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. Not implemented (85) February 20, 2001

  13. Hep B Vaccine Implementation in GFCV-Eligible Countries* Implemented (N=18) Approved (N=24) Application pending (N=16) *4th tranche-June 2001 Not yet eligible - DTP3<50% (N=16)

  14. 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

  15. Effect of Routine Infant Immunization on the Prevalence of Chronic HBV Infection Chronic HBV infection No. Age Vaccine Before After Study Tested Year (yrs) Coverage Program 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%

  16. Age of Acquisition of Chronic HBV Infections in High Endemic Countries % of Chronic Infections Age of Acquisition Perinatal 10-30 Young children 65-80 Adolescents/Adults <5

  17. Strategies to Prevent 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

  18. Strategies to Prevent Perinatal HBV Transmission (2) Integrate 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

  19. Priority of Giving a Birth DoseIssues 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

  20. Priority of Perinatal Hepatitis B Prevention High 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

  21. 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

  22. 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

  23. Components of Strategies to Prevent HBV Transmission • Hepatitis B immunization • Universal infant immunization • Prevent perinatal transmission • Catch-up immunization • Prevent nosocomial HBV transmission

  24. HBV Transmission in Healthcare Settings Patient Patient • Unsafe injection practices • Reuse of contaminated • medical equipment • Blood transfusion • Use safe injection practices • Use sterile equipment • Screen blood supply Patient Provider • Use standard precautions • Vaccinate HCW • Needlestick/sharps injuries Provider Patient • Invasive surgical procedures • Use standard precautions

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