Hepatitis B Post Vaccination Surveillance：乙型肝炎疫苗接种后的监测

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1、WORLD HEPATITIS DAY 2013Johannesburg,Gauteng29th July,2013HeadSouth African Vaccination and Immunisation CentreCo-DirectorWHO Rotavirus Regional Reference Laboratory for Africa&MRC/UL Diarrhoeal Pathogens Research UnitProfessor and Academic ChairDepartment of Virology,University of Limpopo(Medunsa C

2、ampus)&National Health Laboratory Service,PRETORIA,South AfricaEdina Amponsah-Dacosta Edina Amponsah-Dacosta On behalf ofOn behalf of Introduction of hepatitis B vaccine into NIPs Methods to evaluate impact of hepatitis B vaccination Short-term vs.long-term measure of impact of vaccination Examples

3、of representative nationwide sero-surveys of impact of hepatitis B vaccination Concluding Remarks Hepatitis B vaccine is the first vaccine against cancer Available since the early 80s Prevents 0.5 million deaths/year from acute and chronic hepatitis B virus(HBV)infection Recommendation by WHO(1994)H

4、ep B vaccine should be introduced into NIPs:o Countries with HBsAg prevalence 8%by 1995o Global introduction by 1997 South Africa was among the first 10 countries to introduce hepatitis B vaccine on the African continent(April,1995)Introduction of hepatitis B vaccine into Introduction of hepatitis B

5、 vaccine into NIPsNIPs Huge discrepancies between 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 impa

6、ct WHO/UNICEF EstimatesHepatitis B prevention programme Hepatitis B prevention programme and monitoring vaccine impactand monitoring vaccine impactPOST-VACCINATION SURVEILLANCEDefine epidemiology of diseaseAssess and quantify disease burdenDevelop comprehensive prevention strategyIdentify resources&

7、implement vaccineEnsure sustainabilityEvaluate programme effectivenessMonitor ImpactMonitor Impact Hepatitis B is grossly under-diagnosed and under-reporteddifficult to quantify and assess burden of infection difficult to quantify and assess burden of disease To assess impact of vaccinationmeasure t

8、he burden of disease or burden of infection?Sero-survey +I +Prevalence of infection Acute DiseaseSurveillance +I or C*+Incidencenewinfection Risk factor information Morbidity&Mortality +I or C +Incidence chronicsequeleaFeasibilityExpenseFrequency ofevaluationProgram effectiveness short-term long-ter

9、mInformationcollectedCoverage Survey +I*-Coveragedata*I=intermittent;C=continuous Sero-surveys in targeted cohorts Short-term measure of impact of vaccination Targeted cohorts:Vaccinated cohorts Ideally,first survey within 2-5 years of start of programme Periodic surveys thereafter(e.g.,every 5 year

10、s)Increase in protection in vaccinated cohorts Reduction in hepatitis B chronic carriageStudies in targeted populations Studies in targeted populations(Vaccinated CohortsVaccinated Cohorts)to assess)to assess effectiveness of the vaccineeffectiveness of the vaccine Objectives were to assess the:-imm

11、unogenicity of hepatitis B vaccine in the field-the effectiveness of immunisation in reducing HBsAg carriage in 10 mIU/ml)86.8%(N=519)95.6%for 8-12 mo(n=153)87.0%(N=769)HBsAg positivity0.0%(N=578)0.4%(N=756)Anti-HBc positivity0.9%(N=582)0.5%(N=770)Effectiveness of hepatitis B vaccine within EPI-SA:T

12、wo independent studiesProtective Efficacy of Hepatitis B vaccine within EPI(SA):Comparison of three(3)field studies Schoub et al,Bull of WHO 2002;80(4):277-281 Tsebe et al,Vaccine 2001;19:3919 3926 Simani et al,Vaccine 2021;27:140-151Tsebe et al,2001Schoub et al,2002Simani et al,2009HIV-veHIV+veTOTA

13、LMean age(months)23.3(8 mo-5 yrs)1811.9(5-24 mo)10.9(5-24 mo)11.4(5-24 mo)Anti-HBs positivity(10 mIU/ml)86.8%(N=598)95.6%for 8-12 mo(n=153)87.0%(N=769)85.7%(N=230)78.1%(N=73)83.8%(N=303)HBV chronic carriage(HBsAg positivity)0.0%(N=578)0.4%(N=756)0.4%(N=230)2.7%(N=73)0.9%(N=303)Anti-HBc positivity0.9

14、%(N=582)0.5%(N=770)2.7%(N=230)3.0%(N=73)2.9%(N=303)Chronic HBV infectionStudyYear No.TestedAge(yrs)Vaccine CoverageBeforeProgramAfter ProgramAlaska19952681-10 96%16%0.0%Taiwan19944247-1073%10%1.1%Samoa19964357-8 87%7%0.5%Lombok199425194 90%6.2%1.9%Ponape19943643-482%NA 1.0%Micronesia1992544 2 40%12%

15、3.0%South Africa220025781-274%10%0.4%20017561-574%10%0.0%South Africa1Has vaccination influenced population immunity?Has vaccination influenced the epidemiology of HBV?Hepatitis B chronic carriage?Population-based studies to assess Population-based studies to assess immunity and chronic carriage to

16、HBVimmunity and chronic carriage to HBVDemographics of study populationMean age(standard deviation)Sex(%)Provinces(No.of samples)MaleFemaleUnknown*Post-Vaccine Intro.1-16 years(n=635)8.7 years(4.9)276(49.2%)350(50.5%)9(0.3%)Gauteng(689)North West(408)Mpumalanga(63)Limpopo(47)Northern Cape(1)Pre-Vacc

17、ine Intro.17-25 years(n=571)21.9 years(2.4)131(23.3%)439(76.5%)1(0.2%)Total(N=1206)17 years(7.2)407(33.7%)789(65.4%)10(0.8%)*Subjects gender not recordedHas hepatitis B vaccination influenced population immunity?(post-vaccine introduction)(pre-vaccine introduction)p 0.0001Immunity(anti-HBs alone;2 m

18、IU/mL)to Immunity(anti-HBs alone;2 mIU/mL)to hepatitis Bhepatitis B57.0%13.0%6.4%Detectable immunity(anti-HBs alone)within Detectable immunity(anti-HBs alone)within the post-vaccine introduction populationthe post-vaccine introduction population76.1%50.0%46.3%Has population hepatitis B chronic carri

19、age decreased?(post-vaccine introduction)(pre-vaccine introduction)Immunity(anti-HBs alone;2 mIU/mL)and hepatitis B chronic carriage(HBsAg)p=0.00357.0%1.4%13.0%4.2%Immunity(anti-HBs alone;2 mIU/mL)and chronic carriage(HBsAg)in the post-vaccine introduction group76.1%50.0%46.3%0.5%1.3%2.2%17 years of

20、 universal hepatitis B vaccination has been a remarkable success Population immunity to HBV is high(57.0%)Chronic carriage is significantly reduced in the populationHowever,the observation that chronic carriage increases as immunity wanes sparks the debate for a pre-adolescence hepB vaccine boosterA

21、 representative nationwide hepatitis B sero-survey is recommended to better ascertain the long-term impact of universal hepB vaccination in South Africa Highlights from the study Timing of survey relative to introduction of vaccination programme Age group of interest Sampling procedure Sample=Blood

22、Human resources Laboratory vs.point-of-care tests Laboratory testing algorithm Ethical considerations Key issues for conducting nationwide Key issues for conducting nationwide sero-surveys of the impact of hepB vaccinesero-surveys of the impact of hepB vaccine Good approach for measuring the burden

23、of infection but:requires representative samples often conducted in convenient populations,not representative for the general population children visiting health centers(e.g.EPI clinics)pregnant women,armed force recruits,blood donors,etc Other limiting factors include:need for a blood sample Time-c

24、onsuming,expensive Most important factor:laboratory capacityInherent limitations associated with Inherent limitations associated with sero-surveyssero-surveys There is evidence for elimination of chronic carriage in vaccinated cohorts Short-term impact Averting future HBV related liver disease,cirrh

25、osis,HCC and death Almost 17 years after vaccine introduction,there is also evidence for shifting HBV epidemiology in the population Long-term impact Increased population immunity to,and reduced chronic carriage of,HBV There is a need for a representative nationwide sero-survey to assess the long-term impact of universal hepatitis B vaccination in South Africa.Concluding RemarksConcluding Remarks