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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 (Me
2、dunsa Campus) & National Health Laboratory Service, PRETORIA, South AfricaEdina Amponsah-Dacosta On behalf ofIntroduction of hepatitis B vaccine into NIPsMethods to evaluate impact of hepatitis B vaccinationShortterm vs. longterm measure of impact of vaccinationExamples of representative nationwide
3、serosurveys of impact of hepatitis B vaccinationConcluding RemarksHepatitis 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)Hep B vaccine should be introduce
4、d into NIPs:oCountries with HBsAg prevalence 8% by 1995oGlobal 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 NIPsHuge discrepancies between immunization coverage estima
5、tes 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 EstimatesHepatitis B prevention programme and monitoring vaccine
6、 impactPOST-VACCINATION SURVEILLANCEDefine epidemiology of diseaseAssess and quantify disease burdenDevelop comprehensive prevention strategyIdentify resources & implement vaccineEnsure sustainabilityEvaluate programme effectivenessMonitor ImpactHepatitis B is grossly under-diagnosed and under-repor
7、teddifficult 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?Sero-survey + + I + + Prevalence of infection Acute DiseaseSurveillance + + I or C* + + Incidencenewinfection
8、Risk factor information Morbidity& Mortality + + I or C + +Incidence chronicsequeleaFeasibilityExpenseFrequency ofevaluationProgram effectiveness short-term long-termInformationcollectedCoverage Survey + + I* - -Coveragedata* I=intermittent; C=continuousSero-surveys in targeted cohortsShort-term mea
9、sure of impact of vaccinationTargeted cohorts: Vaccinated cohortsIdeally, first survey within 2-5 years of start of programmePeriodic surveys thereafter (e.g., every 5 years)1.Increase in protection in vaccinated cohorts 2.Reduction in hepatitis B chronic carriageStudies in targeted populations (Vac
10、cinated Cohorts) to assess effectiveness of the vaccineObjectives were to assess the:- immunogenicity 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)
11、0.4%(N = 756)Anti-HBc positivity0.9% (N = 582)0.5%(N = 770)Effectiveness of hepatitis B vaccine within EPI-SA: Two independent studiesProtective Efficacy of Hepatitis B vaccine within EPI (SA): Comparison of three (3) field studiesSchoub et al, Bull of WHO 2002; 80 (4): 277 - 281Tsebe et al, Vaccine
12、 2001; 19: 3919 3926Simani et al, Vaccine 2021; 27: 140-151Tsebe et al, 2001Schoub et al, 2002Simani et al, 2009HIV-veHIV+veTOTALMean 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.
13、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%(N = 582)0.5%(N = 770)2.7%(N = 230)3.0%(N = 73)2.9%(N = 303)Effect of Routine Infant Immunization on the Prevalence of Chronic HBV Infect
14、ionChronic 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% 3.0%South Africa220025781-274%10%0.4%20017561
15、-574%10%0.0%South Africa11.Has vaccination influenced population immunity?2.Has vaccination influenced the epidemiology of HBV?Hepatitis B chronic carriage?Population-based studies to assess immunity and chronic carriage to HBVDemographics of study populationMean age (standard deviation)Sex (%)Provi
16、nces(No. of samples)MaleFemaleUnknown*Post-Vaccine Intro.116 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-Vaccine Intro.1725 years (n=571)21.9 years (2.4)131(23.3%)439 (76.5%)1 (0.2%)Total (N=1206)17 years (7.2
17、)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 mIU/mL) to hepatitis B57.0%13.0%6.4%Detectable immunity (anti-HBs alone) within the post-vac
18、cine introduction population76.1%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=0.00357.0%1.4%13.0%4.2%Immunity (anti-HBs alone; 2 mIU/mL) and chronic ca
19、rriage (HBsAg) in the post-vaccine introduction group76.1%50.0%46.3%0.5%1.3%2.2%1.17 years of universal hepatitis B vaccination has been a remarkable successPopulation immunity to HBV is high (57.0%)Chronic carriage is significantly reduced in the population2.However, the observation that chronic ca
20、rriage increases as immunity wanes sparks the debate for a preadolescence hepB vaccine booster3.A representative nationwide hepatitis B serosurvey is recommended to better ascertain the longterm impact of universal hepB vaccination in South Africa Highlights from the study1.Timing of survey relative
21、 to introduction of vaccination programme2.Age group of interest 3.Sampling procedure4.Sample=Blood5.Human resources6.Laboratory vs. pointofcare tests7.Laboratory testing algorithm 8.Ethical considerations Key issues for conducting nationwide sero-surveys of the impact of hepB vaccineGood approach f
22、or 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 recruits, blood donors, etcOther limiting factors include:ne
23、ed for a blood sampleTimeconsuming, expensiveMost important factor: laboratory capacityInherent limitations associated with sero-surveysThere is evidence for elimination of chronic carriage in vaccinated cohorts Shortterm impactAverting future HBV related liver disease, cirrhosis, HCC and deathAlmos
24、t 17 years after vaccine introduction, there is also evidence for shifting HBV epidemiology in the population Longterm impactIncreased population immunity to, and reduced chronic carriage of, HBVThere is a need for a representative nationwide serosurvey to assess the longterm impact of universal hepatitis B vaccination in South Africa.Concluding RemarksThank You For Your Attention
