Transcript Hepatitis B Prevention

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
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
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
Geographic Distribution of Chronic HBV Infection
HBsAg Prevalence
8% - High
2-7% - Intermediate
<2% - Low
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
Routes of HBV Transmission
Age Group Route(s) of Infection
Endemicity
Low Int High
Newborn
•mother to infant
++
Childhood
•child to child
•unsafe injections
++ +++ ++++
- +
++
Adolescent/
Adult
•sexual contact
•injecting drug use
•unsafe injections
++
++++ ++
+++ ++
- +/-
++
+
+
+
Age of acquisition of chronic
HBV infections by endemicity
Low
Perinatal
Intermediate
Childhood
High
Adolescent/Adult
Hepatitis B Immunization Programs
Objective
Prevent chronic HBV infections
• prevent chronic liver disease
• reduce the reservoir for
transmission of new infections
Components of Strategies to
Prevent HBV Transmission
• Hepatitis B immunization
– Universal infant immunization
– Prevent perinatal transmission
– Catch-up immunization
• Prevent nosocomial HBV transmission
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
Global Status of Hepatitis B Immunization Policy
as of January 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.
February 20, 2001
Implemented (129)
Not implemented (85)
Hep B Vaccine Implementation in
GFCV-Eligible Countries*
Implemented (N=18)
*4th tranche-June 2001
Approved (N=24)
Application pending (N=16)
Not yet eligible - DTP3<50% (N=16)
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
Effect of Routine Infant Immunization on the
Prevalence of Chronic HBV Infection
Chronic HBV infection
Vaccine
Before
After
Coverage Program Program
Study
Year
No.
Tested
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%
Age
(yrs)
Age of Acquisition of Chronic HBV
Infections in High Endemic Countries
Age of Acquisition
% of Chronic Infections
Perinatal
10-30
Young children
65-80
Adolescents/Adults
<5
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
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
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
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
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
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
Components of Strategies to
Prevent HBV Transmission
• Hepatitis B immunization
– Universal infant immunization
– Prevent perinatal transmission
– Catch-up immunization
• Prevent nosocomial HBV transmission
HBV Transmission in Healthcare Settings
Patient
•Unsafe injection practices
•Reuse of contaminated
medical equipment
•Blood transfusion
Patient
•Needlestick/sharps injuries
Provider
•Invasive surgical procedures
Patient
•Use safe injection practices
•Use sterile equipment
•Screen blood supply
Provider
•Use standard precautions
•Vaccinate HCW
Patient
•Use standard precautions