1、WORLD HEPATITIS DAY 2013Johannesburg, Gauteng29th July, 2013,JEFFREY MPHAHLELE,HeadSouth African Vaccination and Immunisation CentreCo-DirectorWHO Rotavirus Regional Reference Laboratory for Africa& MRC / UL Diarrhoeal Pathogens Research UnitProfessor and Academic ChairDepartment of Virology, Univer
2、sity of Limpopo (Medunsa Campus) & National Health Laboratory Service, PRETORIA, South Africa,Edina Amponsah-Dacosta On behalf of,Introduction of hepatitis B vaccine into NIPsMethods to evaluate impact of hepatitis B vaccinationShort-term vs. long-term measure of impact of vaccinationExamples of rep
3、resentative nationwide sero-surveys of impact of hepatitis B vaccinationConcluding Remarks,OUTLINE,Hepatitis B vaccine is the first vaccine against cancerAvailable since the early 80sPrevents 0.5 million deaths/year from acute and chronic hepatitis B virus (HBV) infectionRecommendation by WHO (1994)
4、Hep B vaccine should be introduced into NIPs:Countries with HBsAg prevalence 8% by 1995Global introduction by 1997South Africa was among the first 10 countries to introduce hepatitis B vaccine on the African continent (April, 1995),Introduction of hepatitis B vaccine into NIPs,Huge discrepancies bet
5、ween immunization coverage estimates reported by NDoH/EPI unit and those published by WHO/UNICEF Routinely collected immunization coverage data is still not completely reliable and cannot as yet be used to accurately monitor coverage or infer vaccine impact,WHO/UNICEF Estimates,Hepatitis B preventio
6、n programme and monitoring vaccine impact,POST-VACCINATION SURVEILLANCE,Define epidemiology of disease,Assess and quantify disease burden,Develop comprehensive prevention strategy,Identify resources & implement vaccine,Ensure sustainability,Evaluate programme effectiveness,Monitor Impact,Hepatitis B
7、 is grossly under-diagnosed and under-reporteddifficult to quantify and assess burden of infection difficult to quantify and assess burden of diseaseTo assess impact of vaccinationmeasure the burden of disease or burden of infection?,Challenges in monitoring impact of hepatitis B vaccination program
8、me,Sero-survey + + I + + Prevalence of infection,Acute DiseaseSurveillance + + I or C* + + Incidencenewinfection Risk factor information,Morbidity& Mortality + + I or C + +Incidence chronicsequelea,FeasibilityExpenseFrequency ofevaluationProgram effectiveness short-term long-termInformationcollected
9、,Coverage Survey + + I* - -Coveragedata,* I=intermittent; C=continuous,Comparison of methods to evaluate impact of hepatitis B vaccination,Sero-surveys in targeted cohortsShort-term measure of impact of vaccinationTargeted cohorts: Vaccinated cohortsIdeally, first survey within 2-5 years of start of
10、 programmePeriodic surveys thereafter (e.g., every 5 years),Sero-surveys to assess impact of hepatitis B vaccination programme,Increase in protection in vaccinated cohorts Reduction in hepatitis B chronic carriage,Short-term measure of impact of hepatitis B vaccination,Studies in targeted population
11、s (Vaccinated Cohorts) to assess effectiveness of the vaccine,Objectives were to assess the:- immunogenicity of hepatitis B vaccine in the field- the effectiveness of immunisation in reducing HBsAg carriage in 90%,6.2%,1.9%,Ponape,1994,364,3-4,82%,NA,1.0%,Micronesia,1992,544,2,40%,12%,3.0%,South Afr
12、ica2,2002,578,1-2,74%,10%,0.4%,2001,756,1-5,74%,10%,0.0%,South Africa1,Has vaccination influenced population immunity?Has vaccination influenced the epidemiology of HBV?Hepatitis B chronic carriage?,Long-term measure of the impact of hepatitis B vaccination,Population-based studies to assess immunit
13、y and chronic carriage to HBV,*Subjects gender not recorded,Amponsah-Dacosta et al, Medunsa, unpublished data,Has hepatitis B vaccination influenced population immunity?,(post-vaccine introduction),(pre-vaccine introduction),p 0.0001,Immunity (anti-HBs alone;2 mIU/mL) to hepatitis B,57.0%,13.0%,6.4%
14、,Detectable immunity (anti-HBs alone) within the post-vaccine introduction population,76.1%,50.0%,46.3%,Has population hepatitis B chronic carriage decreased?,(post-vaccine introduction),(pre-vaccine introduction),Immunity (anti-HBs alone;2 mIU/mL) and hepatitis B chronic carriage (HBsAg),p=0.003,57
15、.0%,1.4%,13.0%,4.2%,Immunity (anti-HBs alone; 2 mIU/mL) and chronic carriage (HBsAg) in the post-vaccine introduction group,76.1%,50.0%,46.3%,0.5%,1.3%,2.2%,17 years of universal hepatitis B vaccination has been a remarkable successPopulation immunity to HBV is high (57.0%)Chronic carriage is signif
16、icantly reduced in the populationHowever, the observation that chronic carriage increases as immunity wanes sparks the debate for a pre-adolescence hepB vaccine boosterA representative nationwide hepatitis B sero-survey is recommended to better ascertain the long-term impact of universal hepB vaccin
17、ation in South Africa,Highlights from the study,Timing of survey relative to introduction of vaccination programmeAge group of interest Sampling procedureSample=BloodHuman resourcesLaboratory vs. pointofcare testsLaboratory testing algorithm Ethical considerations,Key issues for conducting nationwid
18、e sero-surveys of the impact of hepB vaccine,Good approach for measuring the burden of infection but: requires representative samplesoften conducted in convenient populations, not representative for the general populationchildren visiting health centers (e.g. EPI clinics)pregnant women, armed force
19、recruits, blood donors, etcOther limiting factors include:need for a blood sampleTime-consuming, expensiveMost important factor: laboratory capacity,Inherent limitations associated with sero-surveys,There is evidence for elimination of chronic carriage in vaccinated cohorts Short-term impactAverting
20、 future HBV related liver disease, cirrhosis, HCC and deathAlmost 17 years after vaccine introduction, there is also evidence for shifting HBV epidemiology in the population Long-term impactIncreased population immunity to, and reduced chronic carriage of, HBVThere is a need for a representative nationwide sero-survey to assess the long-term impact of universal hepatitis B vaccination in South Africa.,Concluding Remarks,Thank You For Your Attention,
