规范化甲肝减毒活疫苗(H2株)现场效果研究

目的 观察我国研制的规范化甲肝减毒活疫苗（H2株）的流行病学保护效果。方法 3515名甲肠易感儿童按出生单双月份随机分组，其中接种组1804名，对照组1653名。观察接种疫苗后两组甲型肝炎发病率。结果 对照组发现甲肝病例14例，发病率8.47‰；疫苗组1例，发病率0.55‰，保护率93.51%，95％下可信限为64.56%。结论 国产规范化甲肝减毒活疫苗与国外甲型肝炎灭活疫苗保护效果相似。     

甲型肝炎减毒活疫苗暴露后预防效果的观察

目的：观察国产甲型肝炎（甲肝）减毒活疫苗暴露后预防效果。方法：在河北正定某自然村甲型肝炎流行开始时,对该村小学所有学生采集血清,检测甲肝易感性,并给予接种一剂甲肝减毒活疫苗[H2株,滴度为10^6.67组织培养半数感染量（TCID50）]。接种后18天（最短潜伏期）与最后1例甲肝病例发生后40天（最长潜伏期）两次采集两组观察对象血清,观察两组感染与发病情况。结果：在接种后18天以内及18天至最后一病例发生后40天（流行结束）两个观察期内,接种组与非接种组新感染率与罹患率均差异无显著意义（P＞0．05）。结论：在本次流行中,未能发现甲型肝炎减毒活疫苗用于暴露后预防的效果,暴露后预防仍应以免疫球蛋白为主。     

甲型肝炎减毒活疫苗免疫效果的进一步观察

目的 进一步观察我国研制的规范化甲型病毒性肝炎（简称甲肝）减毒活疫苗流行病学和血清学效果。方法 在河北省阜城县以群体随机分组法接种Ｈ２株甲肝减毒活疫苗，疫苗组５５５１人，对照组６４８５人。观察全人群和上述两组人群甲肝发病率，出现流行时采集两组人群血液，检测抗－ＨＶＡ ＩｇＧ和ＩｇＭ，分析疫苗保护效果。结果 １９９７年５月完全疫苗接种，疫苗接种后７个月内为甲肝散发，发病率为０．５５／１０万；疫苗组未     

大规模接种甲肝减毒活疫苗(H2株)后人群的免疫持久性

目的评估甲肝减毒活疫苗(H2株)大规模接种后人群的免疫持久性以达到控制甲肝流行的目的。方法选择220名免前抗甲肝抗体阴性的儿童(年龄1～3岁)作血清学追踪观察,分别于接种H2株疫苗后的2月、12月、6年和10年观察抗甲肝抗体的阳性率和几何平均滴度。另外根据随机原则选择不同年龄组的人群(3岁、6岁、9岁、15岁、18岁、25岁和35岁)比较疫苗接种前和接种后10年抗甲肝抗体的阳性率。10年流行病学追踪观察疫苗接种率和甲肝发病率之间的关系。血清检测方法用ELISA法(用WHO标准品校正)和ABBOTT(美国)AxsymmEIA法。结果在血清学追踪观察人群中疫苗接种后2个月和接种后10年,抗体阳转率分别为98.6%和80.2%;18岁以下年龄组疫苗接种前和疫苗接种后10年抗体阳性率差异有显著性意义,分别从7.69%升高到70.45%(3岁组)、52.58%升高到71.78%(18岁组)。流行病学效果观察:当疫苗接种率达到57%～74%时,2个试验点无甲肝流行;当疫苗接种率达到85%时,2个试验点无甲肝病例的发生;当疫苗接种率保持在85%～91%时,1～15岁年龄组儿童连续9年没有甲肝病例发生。结论通过10年观察,甲肝减毒活疫苗大规模的免疫接种在预防和控制甲肝的流行与发生过程中具有显著的免疫持久性。     

冻干甲型肝炎减毒活疫苗H2株的安全性和免疫原性研究

为观察H2株冻干甲型肝炎(甲肝)减毒活疫苗接种人体后的安全性和免疫原性，选择广西壮族自治区蒙山县一小学学生(年龄7～12岁)164人和浙江省台州市椒江区一幼儿园儿童(年龄3-6岁)114人为接种对象，免疫前筛选抗甲肝病毒IgG抗体(抗-HAV-IgG)阴性，血清丙氨酸氨基转移酶(SGPT)正常，无肝炎病史、症状和体征者，分别接种2个批号的H2株冻干甲肝活疫苗。观察接种疫苗后30min，8、24、48、72h的局部及全身反应，以后隔天记录体温及其它有关临床反应。接种疫苗后1、2个月采静脉血测定SGPT及抗-HAV-IgG，同时长期随访检测免疫后13、24个月血清抗-HAV-IgG水平。检测用酶免疫测定（EIA)竞争抑制法，用世界卫生组织(WHO)提供的标准品(含100mlU／ml)进行标定。结果显示：在整个观察期间，所有观察者未见中、强反应及其它临床反应发生，SGPT检测结果无异常升高。H2株冻干甲肝活疫苗具有良好的安全性。接种疫苗后2个月抗体阳性率为99．1％-100．0％，13～24个月阳性率仍高达97．8％-98．9％；免疫后2个月抗体几何平均滴度(GMT)达1607mlU/ml，在免疫后24个月抗体GMT仍维持在448．3mlU／ml。表明H2株冻干甲肝活疫苗安全性良好，接种后有较高的抗体阳转率和GMT。     

甲型肝炎病毒H2株减毒活疫苗与乙型肝炎血源疫苗同时接…

本文报道了对学龄前儿童进行甲肝减毒活疫苗（Ｈ２株）和乙肝血源疫苗同时接种的免疫效果观察。投苗前１周通过血清学检测筛检出３００名地ＨＡＶ，ＨＢＶ易感的健康儿童，分为三组观察，即单独接种甲肝疫苗的Ｉ组，单独接种乙肝疫苗的Ⅱ组和同时接种甲，乙肝疫苗的Ⅲ组。甲肝疫苗接种后１个月，Ⅰ组和Ⅲ组的血清抗体阳转率分别为８７．３９％和９０．１４％；而７个月后分别为９８．３１％和１００％，抗－ＨＡＶ滴度在１：１－１：     

甲型肝炎减毒活疫苗免疫原性和保护效果的初步观察

目的观察我国研制的规范化甲型病毒性肝炎（以下简称甲型肝炎）减毒活疫苗Ｈ２株与ＬＡ１株的免疫原性并考核其保护效果。方法１３５３４０名受试儿童以系统随机分组方法，另３６００１２名儿童以整群随机分组方法，分为疫苗接种组与对照组。观察并比较两组甲型肝炎发病率。此外，检测甲型肝炎抗体为阴性的部分易感者，在接种Ｈ２株与ＬＡ１株后２～６个月，抽血检测甲型肝炎抗体阳转率与几何平均滴度（ＧＭＴ）。结果对照组发现甲型肝炎３７例，两株疫苗接种组均未发现病例，保护率均为１００％，两组保护率合并后的９５％可信限下限为９２１％。用于现场研究的Ｈ２株（１０７０ＴＣＩＤ５０）抗体阳转率为９４８７％，ＬＡ１株（１０６７５ＴＣＩＤ５０）为８３１６％。抗体阳转率与疫苗滴度有剂量效应关系。活疫苗接种２次，抗体阳转率达１００％。观察期间未发现任何严重副反应。结论Ｈ２株与ＬＡ１株甲型肝炎减毒活疫苗免疫原性良好，与国外甲型肝炎灭活疫苗相比具有同等免疫效果     

甲型肝炎减毒活疫苗病毒的水平传播

目的 探讨甲型肝炎（甲肝）减毒活疫功接种后的病毒水平传播。方法 在昆明市安宁县2个观察点筛选出丙氨酸转氨酶（ALT）正常、甲肝（HAV）抗体（抗－HAV）阴性的4－7岁儿童199人,按1：1.4比例分接种组（82人）和接触组（117人）进行H2株甲肝减毒活疫苗病毒的水平传播观察;另外,取接种者和接触者HAV检测阳性的粪便悬液上清,分别静脉接种于8普通狨猴（Callithrix jacchus）体内,观察粪便HAV毒力水平。结果 接种组接种后6周抗体阳转率为97.6％（80／82）,接触组9周时抗体阳转率为13.7％（16／117）,两组儿童肝功能均未见异常 种组和接触组的粪便HAV检出率分别为89.5%(34/38)和70.7%(53/75）;以2株接种者粪便HAV和2株接触者粪便HAV感染的8只狨猴,均未检出血清酶升高和肝脏组织病理学改变,抗－HAV和2株接触者粪便HAV感染的8只狨猴,均未检出血清酶升高和肝脏组织病理学改变,抗－HAV阳转时间延迟且效价低。结论 H2株甲肝减毒活安全性及免疫原笥良好,疫苗病毒在人体内增殖活跃,且保持减毒性能稳定,能在人群中造成水平传播,但不会引发甲肝。     

对恒河猴作为鉴定甲肝闰毒活疫苗的动物模型评估

１９９５￣１９９７年期间，采用１０批甲肝减毒活疫苗（Ｈ２株）对５０只恒河猴进行甲肝减毒活疫苗接种观察，接种后８周内检测ＡＬＴ、抗－ＨＡＶ抗体及肝穿病理检查，其结果表明恒河猴可作为鉴定甲肝减毒活疫苗的较好动物模型。     

儿童水痘减毒活疫苗、甲肝减毒活疫苗联合接种效果分析

目的研究分析儿童水痘减毒活疫苗和甲肝减毒活疫苗联合接种免疫原性及安全性。方法选取600例甲肝易感者和健康水痘年龄为18到24月的儿童为本次研究过程中的研究对象,随机分为三组,每组各为200例,A组接种甲肝疫苗,B组接种水痘疫苗,C组联合接种甲肝减毒活疫苗和水痘减毒活疫苗,比较安全性和免疫原性相关指标。结果 B组和C组的水痘抗体转阳率均为100%,C组的抗体几何平均滴度显著高于B组,具有统计学差异(P0.05)。A组和B组以及C组发生不良时间的概率无显著差异,不具有统计学意义(P0.0%)。结论儿童水痘减毒活疫苗和甲肝减毒活疫苗联合接种与单独接种相比,安全性和免疫原性较好,具有临床进一步推广和应用的概率。     

甲型肝炎减毒活苗免疫原性和保护效果的初步观察

目的 观察我国研制的规范化甲型病毒性肝炎（以下简称甲型肝炎）减毒活疫苗Ｈ２株与ＬＡ－１株的免疫原性并考核其保护效果。方法 １３５３４０名受试儿童以系统随机分组方法,另３６００１２名儿童以整群随机分组方法,为分疫苗接种组与对照组,观察并比较两组甲型肝炎发病率。此外,检测甲型肝炎抗体为阴性的易感者,在接种Ｈ２株与ＬＡ－１株后２－６个月,抽血检测甲型肝炎抗体阳转率与几何平均滴度（ＧＭＴ）。结果 对照组发     

Recent progress in vaccines for amebiasis

The persistence of amebiasis as a global health problem, despite the availability of effective treatment, has led to the search for vaccines to prevent this deadly disease. Recent clinical studies suggest that mucosal immunity could provide some protection against recurrent intestinal infection with E. histolytica, but there is contradictory evidence about protective immunity after amebic liver abscess. Progress in vaccine development has been facilitated by new animal models that allow better testing of potential vaccine candidates and by the application of recombinant technology to vaccine design. Oral vaccines utilizing amebic antigens either co-administered with some form of cholera toxin or expressed in attenuated strains of Salmonella or Vibrio cholera have been developed and tested in animals for mucosal immunogenicity. Although there has been significant progress on a number of fronts, there are unanswered questions regarding the effectiveness of immune responses in preventing disease in man and, as yet, no testing of any of these vaccines in humans has been performed.     

Safety and effectiveness of the new inactivated hepatitis A virus vaccine.

PURPOSE: To examine the evidence concerning the safety and effectiveness of the inactivated hepatitis A virus vaccine recently licensed for use in Canada. DATA SOURCES: The main source of information were papers presented at the International Symposium on Active Immunization against Hepatitis A, held in Vienna, Austria, Jan. 27-29, 1992. The bibliographies of these papers were searched for additional references. Recent articles describing the new vaccine and the epidemiologic aspects of infection with hepatitis A virus (HAV) were also reviewed. STUDY SELECTION: Peer-reviewed reports of trials approved by a government regulatory agency on the safety, immunogenic properties and efficacy of the vaccine. DATA EXTRACTION: The authors assembled key reports on adverse reactions, protection from disease and serologic assessment of immune response in vaccine recipients; data from these reports were tabulated and analysed. RESULTS OF DATA SYNTHESIS: The new vaccine contains the HM175 strain of HAV, which is adapted to grow in tissue culture. The virus is purified, inactivated with the use of formaldehyde and adsorbed onto aluminum hydroxide. The recommended dose for adults is 720 enzyme-linked immunosorbent assay (ELISA) units in a 1.0-mL dose and for children 360 ELISA units in a 0.5-mL dose, injected intramuscularly. The usual schedule is three serial doses, the second given 1 month and the third 6 to 12 months after the initial dose. Reported side effects are infrequent and minor. In healthy persons who have received two doses, the seroconversion rate is almost 100%. Protective efficacy after two doses is estimated to be 94%. However, the persistence of protective antibodies has been studied only over the short term (3 years). CONCLUSIONS: The new HAV vaccine is safe, effective and best suited to pre-exposure prophylaxis in people with an increased risk of infection for an extended period, such as travellers to areas where the disease is endemic. Further studies are needed to determine whether infants respond well to the vaccine and whether the vaccine protects recipients from subclinical infection and associated fecal shedding of HAV. Controlled trials to determine the duration of protection beyond 3 years and the effects of more rapid dosage schedules are also needed.     

Immunological effects of live attenuated hepatitis A vaccine]

11,451 health persons were inoculated with live attenuated hepatitis A vaccine (H2 strain) in 3 batches. Among them, 785 were tested for anti-HAV antibody response by ELISA. The results showed that H2-strain vaccine got a quick antibody response (2-5 weeks) and a high seroconversion rate (92.9%). Also, the titers of antibodies to HAV ranged from 1:2 to 1:32. The seroconversion of the first 12 recipients lasted for 3 years. The primary epidemiological studies demonstrated that H2-strain vaccine was effective in preventing hepatitis A. The relation between the positive rate of antibody and different dosage showed that 10(6.5)TCID50 could get a highest seroconversion rate (100%).     

甲型肝炎灭活疫苗和冻干减毒活疫苗接种后1年的免疫原性研究

目的评价甲型肝炎灭活疫苗和冻干减毒活疫苗接种1剂1年后的免疫原性。方法采用单一中心随机双盲试验设计,对18月龄~4岁健康幼儿受试者随机接种1剂设盲的甲肝灭活疫苗或甲肝减毒活疫苗。接种前及接种后12个月,采用微粒子酶免法（MEIA）定量检测受试者甲型肝炎抗体（抗-HAV）。结果免疫后1年,甲肝灭活疫苗组和甲肝减毒疫苗组分别有124人和135人完成试验,抗-HAV阳转率分别为95.2%和91.1%,抗-HAV的几何平均浓度（GMC）分别为101.7 IU/L和65.5 IU/L,甲肝灭活疫苗免疫的抗体水平明显高于甲肝减毒活疫苗（P〈0.001）。结论接种1剂甲肝灭活疫苗或甲肝减毒活疫苗后12个月,均可产生良好的免疫效应,甲肝灭活疫苗免疫的抗体水平明显高于甲肝减毒活疫苗。     

A two-dose combined vaccine against hepatitis A and hepatitis B in healthy children and adolescents compared to the corresponding monovalent vaccines

BACKGROUND: Immunization against hepatitis A and B has been available for some time, protecting against both infections. With a view to achieving further reduction in the number of interventions and increasing convenience of the vaccinee, we investigated the reactogenicity and immunogenicity of a combined hepatitis A and B vaccine in healthy 4- to 20-year-old subjects at a 0, 6-month schedule. METHODS: Two hundred forty-eight study subjects were allocated to two study groups and received either two doses of the combined hepatitis A and B vaccine (68% of subjects) or the corresponding monovalent hepatitis A and hepatitis B vaccines (32% of subjects) concomitantly in opposite arms. Reactogenicity was assessed via diary cards after each vaccination. Serum samples were analyzed at months 1, 2, 6, and 7. RESULTS: All vaccines were well tolerated and very few symptoms were scored as severe. All but one subject seroconverted for anti-hepatitis A virus (anti-HAV) antibodies (98.6%) and 100% of subjects seroconverted for anti-hepatitis B (HBs) antibodies, with respective seroprotection rates of 98.7% for the combined vaccine group and 95.9% for the concomitant vaccine group (p >0.05), respectively. Geometric mean titers were higher in the group receiving the combined vaccine: 6,635 mIU/mL vs. 2,728 mIU/mL (p = 0.0001) for anti-HAV and 3,362 mIU/mL vs. 1,724 mIU/mL (p = 0.0205) for anti-HBs, respectively. Younger subjects had a stronger immune response compared to older subjects. CONCLUSIONS: The combined hepatitis A and B vaccine was well tolerated at this two-dose schedule. The combined vaccine had higher immunogenicity, probably explained by a adjuvant effect of the antigens. Vaccination programs requiring fewer injections will most likely have a positive impact on compliance rate and comfort of the vaccinee.     

Dengue Vaccine: The Current Status

Dengue fever is a re-emerging public health problem with two-fifths of the world population being at risk of infection. Since there are no antiviral drugs available against the dengue virus, and vector control programmes have been largely unsuccessful in preventing outbreaks, vaccination seems to be the most viable option for preventing infection. An ideal dengue vaccine should provide long lasting immunity against all four serotypes of the virus. The envelope protein of the virus plays a key role in vaccine development. The present day candidate vaccines includes a live attenuated tetravalent vaccine, intertypic chimaeric vaccines based on live attenuated dengue virus vectors, chimaeric vaccines based on the live attenuated Yellow Fever 17D vector and recombinant vaccines which include vaccines based on flavivirus and non-flavivirus vectors. Tetravalent live attenuated vaccines, intertypic chimaeric vaccines and chimaeric vaccines are being tested in human trials. Recombinant DNA vaccines based on flavivirus and non-flavivirus vectors are being tested in animal trials. Recent studies have shown that the tetravalent formulations may elicit an unbalanced immune response. Research is continuing to find means of obtaining a balanced response to all antigens in the tetravalent formulations.Key Words: Dengue fever, Candidate vaccines, Clinical trials     

Evaluation of live attenuated S79 mumps vaccine effectiveness in mumps outbreaks: a matched case-control study

Background Mumps virus infection is a potentially serious viral infection of childhood and early adulthood. In China, live attenuated S79 mumps vaccine has been licensed for pediatric use since 1990. The objective of this study was to determine the effectiveness of live attenuated S79 mumps vaccine against clinical mumps in outbreaks. Methods Cases were selected from mumps outbreaks in schools in Guangzhou between 2004 and 2005. Each case was matched by gender, age and classroom. Vaccination information was obtained from Children＇s EPI Administrative Computerized System. Vaccine effectiveness （VE） was calculated for 1 or 2 doses of S79 vaccine with 95% confidence intervals （CI）. Results One hundred and ninety-four cases and 194 controls were enrolled into the study. VE of the S79 mumps vaccine for 1 dose versus 0 confer protection 80.4% （95% Cl, 60.0%-90.4%） and VEs against mumps in outbreaks for 1 dose of mumps vaccine are similar among those children aged 4-9 years and aged over 10 years old. Conclusion The live attenuated S79 mumps vaccine can be effective in preventing clinical mumps outbreaks.