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艾滋病毒及艾滋病 HIV/AIDS
人类免疫缺陷病毒(艾滋病毒)是一种逆转录病毒，它感染人类免疫系统细胞，摧毁或损害其功能。感染初期没有症状。但是，随着感染的发展，免疫系统开始变弱，患者更加容易遭受所谓的机会性感染。
艾滋病毒感染的最后阶段是获得性免疫缺陷综合征(艾滋病)。艾滋病毒感染者可能经过10-15年才会患艾滋病，抗逆转录病毒药物可以进一步延缓这一进程。
艾滋病毒通过无保护的性交(肛门或阴道)、输入受污染的血液、共用受污染的注射针传播，还可在妊娠、分娩和哺乳期间在母亲及其婴儿之间传播。
The human immunodeficiency virus (HIV) is a V) is a retrovirus that infects cells of the immune system, destroying or impairing their function. As the infection progresses, the immune system becomes weaker, and the person becomes more susceptible to infections. The most advanced stage of HIV infection is acquired immunodeficiency syndrome (AIDS). It can take 10-15 years for an HIV-infected person to develop AIDS; antiretroviral drugs can slow down the process even further.
HIV is transmitted through unprotected sexual intercourse (anal or vaginal), transfusion of contaminated blood, sharing of contaminated needles, and between a mother and her infant during pregnancy, childbirth and breastfeeding.
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1.、艾滋病毒和婴儿喂养 HIV and infant feeding
母乳喂养通常是喂养婴儿的最好方法，一位感染艾滋病毒的妇女也能在孕期、生产或分娩，或母乳喂养中把病毒传染给她的孩子。但是，母乳喂养，特别是早期的纯母乳喂养是提高儿童生存的最为重要因素之一。除降低儿童死亡的危险外，母乳喂养可带来诸多益处。
面对的难题是，要平衡通过母乳喂养使婴儿获得艾滋病毒的风险与由于艾滋病毒以外原因（尤其是营养不良以及诸如非母乳喂养婴儿中罹患的腹泻和肺炎等严重疾病）使其面临更高的死亡风险。基于上述原因，就那些母亲感染了艾滋病毒的婴儿而言，卫生工作者在对其确定和鼓励最佳喂养做法时面临真正的挑战。
近年来已积累了关于艾滋病毒和婴儿喂养的大量证据。这些证据显示，无论是向感染了艾滋病毒的母亲，还是向暴露于艾滋病毒的婴儿给予抗逆转录病毒药物治疗，都可以显著降低通过母乳喂养传播艾滋病毒的风险。
鉴于这方面的证据，世卫组织在2009年11月发布了一份“快速建议”文件，内含有关《感染艾滋病毒情况下婴儿喂养》的修订原则和建议。同时发布了《适合成人和青少年的抗逆转录病毒治疗》以及《预防母婴传播》的新建议。这些建议合在一起对国家提供了简单、一致、可行的指导，促进并支持感染了艾滋病毒的母亲改善婴儿喂养。
Breastfeeding is normally the best way to feed an infant. A woman infected with HIV, however, can transmit the virus to her child during pregnancy, labour or delivery, or through breastfeeding. However, breastfeeding, and especially early and exclusive breastfeeding, is one of the most valuable interventions for improving child survival. Breastfeeding also confers many benefits in addition to reducing the risk of child mortality.
The dilemma has been to balance the risk of infants acquiring HIV through breastfeeding with the risk of death from causes other than HIV, in particular malnutrition and serious illnesses such as diarrhoea and pneumonia among non-breastfed infants. For these reasons, health workers in countries where both HIV is common and many children die from these other illnesses, have faced a real challenge in identifying and promoting the best feeding practice for infants in their care whose mothers are HIV-infected.
A large body of evidence on HIV and infant feeding has accumulated in recent years which shows that giving antiretroviral drugs (ARVs) to either the HIV-infected mother or HIV-exposed infant can significantly reduce the risk of transmitting HIV through breastfeeding.
In view of this evidence, in 2010 WHO released new Guidelines on HIV and Infant Feeding containing revised principles and recommendations for infant feeding in the context of HIV and a summary of evidence that resulted in the guidelines. At the same time, new recommendations were released on antiretroviral therapy for infants and children, as well as for adults and adolescents, and for the prevention of mother-to-child transmission of HIV. Together, the recommendations provide simple, coherent and feasible guidance to countries for promoting and supporting improved infant feeding by HIV-infected mothers.
2、全球疫苗安全咨询委员会报告 全球疫苗安全咨询委员会会议， 2006年11月29-30日
全球疫苗安全咨询委员会(GACVS)是世卫组织设立的的临床和科研专家咨询机构，旨在对可能具有全球重要性的疫苗安全问题做出独立于世卫组织的、科学严谨的反应。1 GACVS于2006年11月29-30日在瑞士日内瓦召开了第15次会议。2 委员会讨论了许多与所有疫苗有关的一般性问题以及许多特定疫苗的问题。特定疫苗问题的讨论与已长期存在的疫苗以及新的疫苗或还在研发中的疫苗有关。以下的其他问题也给予了考虑。
一般性问题
疫苗安全性监测
在以前的一些会议3 4上，GACVS要求加强全球疫苗药物警戒，特别是在世卫组织国际药物监测合作计划的背景下开展工作。尤其需要关注的方面包括各国的资料传输、资料质量的保证以及资料的处理和分析，并包括及时发现疫苗安全问题的“信号”和采取行动。基于以上要求，由6名GACVS成员组成一个小组，与秘书处密切合作开展工作，以保证该项行动能及时推进。4 全体委员会听取了该小组的工作报告。小组的工作职责范围是：针对在全球层面建立高质量的疫苗接种后不良事件（AEFI）的报告、发现、分析和交流的系统向世卫组织提供咨询意见，并就为实现第一项目标而开展的活动向世卫组织、在瑞典乌普萨拉的世卫组织国际药物监测合作中心（乌普萨拉监测中心，UMC）和会员国提供咨询意见。会议确定了实现这一目标的具体目标和阶段性目标，该小组在今后几年内将承担这些工作。一项非常重要的工作是利用现有的世卫组织网络和其他方法提高疫苗免疫界所有人员对药物警戒的态度和意识。
会议期间提交了秘书处代表和工作小组访问乌普萨拉监测中心的报告。主要行动领域包括：（1）设立疫苗安全性专门职位，以加强UMC疫苗专业能力；（2）帮助招募志愿专家评审员，以评估潜在的疫苗安全问题的“信号”；（3）组织科研专家探讨可以采取哪些优化措施来发现疫苗安全问题的“信号”。药品的解剖学治疗学化学分类索引及规定日剂量 (ATC/DDD) 和世界卫生组织药物字典在疫苗方面存在欠缺，需要加以改进。目前正在制定计划，将审核和提议针对ATC/DDD 的疫苗部分做出适当的修改。这些建议拟在近期会议上向在挪威奥斯陆的世界卫生组织药物统计方法合作中心提出。
世界卫生组织生物制品标准化专家委员会的报告
会议期间总结了世卫组织生物制品标准化专家委员会的工作。委员会制定旨在协助界定有质量保证的生物医药制品的全球规范和标准，包括供疫苗预审使用的质量、效力和安全性方面的规格要求。
委员会最近一次会议于2006年10月23–27日举行。会议期间制定了3份新的书面标准：人乳头瘤病毒疫苗标准、A群脑膜炎球菌结合疫苗标准和关于疫苗稳定性评价的管理要求标准。委员会还确定了15 个新的参比制剂，采用全球计量标准，以指导生产厂商和药品监督管理部门开展生物药品工作。最后，委员会批准了许多有关质量标准的新项目，评议了许多药品监督管理问题，包括大流行性流感疫苗的管理预案和对经联合国机构采购的疫苗开展审批工作。
在讨论委员会报告时，GACVS 注意到制定相关程序以共享疫苗临床试验得到的安全性信息是很有裨益的，并要求秘书处探讨如何开展此项工作。
疫苗配方的安全性
本部分内容的会议源于上次GACVS会议提出的建议，即委员会应该开始主动地观察疫苗配方中防腐剂和其他无活性成分的切实存在的和所认识到的安全性。突出的问题是，与活性成分相比，有关疫苗辅料的信息十分有限。这对于药品监督管理者和生产厂商开展质量保证来说无疑是一项挑战；同样，对卫生工作者开展风险信息沟通也构成了挑战。由于并非频繁注射，疫苗中的少量辅料不大可能显现毒性。但是随着治疗性疫苗的出现，这种情况可能会发生变化，因为可能需要反复给予接种注射。必须建立相关机制，确保得到更多的疫苗配方的详细信息，并对辅料的安全性进行严格评审。
已组建了一个GACVS工作小组来具体探讨这一问题。该小组将在2007年6月的委员会会议上报告他们的工作，包括确定工作重点、提出一份辅料及其潜在不良反应的清单。
青少年和年轻人的疫苗接种: 偶合病状问题和安全性评估
青少年的疫苗接种（包括人乳头瘤病毒疫苗等新疫苗以及一些过去可以获得的疫苗）很可能会成为一个焦点问题。会议期间，相关单位向委员会提交了一份报告，介绍了应用来自美国一家健康维护组织（一种私人健康保险公司）的卫生服务利用资料所开展的初步模式化工作。该项工作表明疫苗接种后很可能会发生各种偶合病状。尤其是出现妇科疾病和自身免疫系统紊乱，而这样的观察报告可能导致公众担忧疫苗的安全性。委员会认识到应进一步重视这一问题。各国在准备引进针对青少年和年轻人的疫苗前，应努力确定特定病状的人群特异性和年龄特异性基线发生率（如自身免疫疾病的发生率）。这将有助于针对各种可能浮现的疫苗安全性问题开展调查研究。对于任何通过监测得到的安全性问题“信号”，都要采用适当的流行病学方法进行彻底调查之后才能得出结论。
与特定疫苗有关的问题
腮腺炎疫苗毒株的安全性
应免疫战略咨询专家组（SAGE）的要求，委员会应更新2003年对腮腺炎疫苗毒株安全性的综合性评述，尤其应注意疫苗引发脑膜炎的风险。根据最新的文献检索和一些疫苗厂商提供的资料，会议向委员会提交了一份有关疫苗安全性状况的综述。
与以前的综述相似，5 委员会注意到有关在接种病毒Urabe、 Leningrad-Zagreb、Hoshino、Torii和Miyahara株腮腺炎疫苗的个体中发生无菌性脑膜炎病例的报道及对发病率的估计，但是由于研究质量和所用监测方法的不同，目前尚无法明确这些疫苗病毒株引起的发病风险是否存在差异。迄今为止的资料表明无菌性脑膜炎发生率低，且使用病毒Jeryl-Lynn和RIT-4385株疫苗后没有经病毒学证明的病例发生；关于Leningrad-3疫苗株的资料有限，且没有资料可以用来评估S79疫苗株的安全性。
使用含有可能导致无菌性脑膜炎风险增加的腮腺炎疫苗株的腮腺炎-麻疹-风疹疫苗（麻-风-腮疫苗）开展强化免疫，已导致不良事件的聚集发生，影响了免疫规划的开展。随着AEFI监测系统的敏感性提高，对强化免疫期间聚集发生的无菌性脑膜炎的辨识能力也得到了加强。已在使用Urabe和Leningrad–Zagreb株疫苗后观察到这种情况。 截至本次会议，所有报告的腮腺炎疫苗引发的无菌性脑膜炎病例都已痊愈。其中有一些只是实验室诊断的病例，几乎没有什么临床意义上的疾病。尽管发生了这些病例，从几年来在发展中国家的常规免疫规划中使用Leningrad–Zagreb株腮腺炎疫苗的经验来看，其风险-利益比还是可以接受的。但是，如果使用可能诱发无菌性脑膜炎风险增加的腮腺炎疫苗株用于强化免疫时，免疫接种规划应实施适宜的风险信息沟通和病例管理策略来应对可能出现的无菌性脑膜炎病例聚集发生的报告。
需要仔细设计和开展研究，藉以比较不同腮腺炎疫苗株的安全性，区分不同疫苗株在不同人群、不同年龄组可能存在的风险差别。对病例定义实行标准化、对不良事件的严重程度实行量化，这都有助于对结果的解释。
GACVS很高兴地注意到英国国家生物标准研究所建立腮腺炎疫苗株毒种库的工作进展，并敦促其加快工作速度，藉以了解不同毒株引起风险的生物学决定因素。委员会要求其提交所有与腮腺炎疫苗安全性相关的新资料，以便更好地评估无菌性脑膜炎或其他与特定疫苗株相关病状的的风险。
HIV感染儿童接种卡介苗的安全性问题
根据新获得的证据，委员会审核了关于HIV感染儿童接种卡介苗（BCG）的政策。在阿根廷和南非进行的回顾性研究表明，在出生时接种卡介苗和之后出现艾滋病的HIV感染儿童中发生播散性BCG疾病的风险更高。据报告，HIV感染儿童中与疫苗接种有关的风险可能超过了疫苗预防严重结核病的利益，尤其是因为BCG对HIV感染儿童的结核病预防效果还不清楚。
世卫组织目前推荐对所有居住在结核病呈高度地方性流行地区的婴儿和居住在低地方性流行的国家但有特别暴露危险的婴儿和儿童给予单次BCG接种。免疫功能受损者禁忌接种BCG，世卫组织也不推荐对已出现HIV感染症状的儿童接种BCG 。
GACVS的结论是：最近的发现表明HIV感染儿童发生播散性BCG疾病的风险较高，故对已知感染了HIV的儿童不应给予BCG接种。
委员会认识到，在对母亲和婴儿的诊断和治疗服务有限的地方很难在出生时确定婴儿是否已感染HIV。在这种情况下，所有婴儿在出生时都应该继续给予BCG接种而无论其是否暴露于HIV，尤其是考虑到在高HIV患病率人群中结核病也呈高度地方性流行。建议对母亲已知是HIV 感染者且出生时接种了BCG的婴儿进行密切随访，以便早期发现和及时治疗任何BCG相关并发症。在具有良好HIV服务的地方，对HIV感染儿童尽可能做到早期发现和给予抗病毒治疗，可以考虑对母亲已知是HIV 感染者的婴儿推迟BCG接种，直到确认这些婴儿没有感染HIV时再接种。
关于Menactra®脑膜炎球菌疫苗和格林-巴利综合征的的最新情况
会议介绍了在美国接种四价脑膜炎球菌结合疫苗（Menactra®）后发生格林-巴利综合征(GBS)的最新情况报告6。截止到2006年9月，美国疫苗不良事件报告系统总共收到17份病例报告（在接种后6周发生GBS）。对相关资料进行分析后提示：接种该疫苗后可能使发生GBS的风险轻微上升（每一百万剂发生1.25例[95%可信限：0.058-5.993]），但是由于报告系统的局限性和GBS本底发病率的不确定性，对这一发现应持审慎态度。
大流行性流感疫苗
委员会讨论了关于全球监测大流行性流感疫苗安全性的计划。委员会强调了建立有力的联络点网络以共享信息和在季节性流感疫苗接种时对该系统进行试点的重要性。该网络旨在确保会员国能迅速、及时获取关于大流行性和季节性流感疫苗安全性的信息，提供能够处理紧急查询的专门资源的途径，启动和协调有关的反应。正在开发网站平台以支持为会员国的各利益相关方收集和传播信息。应仔细筹划这一流感疫苗安全性网络并考虑到大流行可能带来的限制。
鉴于已建成了数个全球传染病、药品或疫苗监测系统，且这些系统可能适合于大流行性流感疫苗安全性监测的某些方面，故全球上市后监测网络的目标是协调各种可利用的资源和支援处理能力不足的地区。尽管正在建立针对大流行性流感疫苗的监测系统，但最初可利用季节性流感疫苗安全性监测作为替代手段。GACVS 将组建一个工作小组努力完成这一目标。该小组将结合一系列世界卫生组织人用大流行性流感疫苗管理预案研讨会开展工作。
在印度使用的流行性乙型脑炎疫苗的安全性
GACVS 审议了印度专家小组的报告。该报告对2006年夏季在印度4个邦使用SA 14-14-2株流行性乙型脑炎减毒活疫苗开展加强免疫后报告的严重不良事件病例进行了评估。免疫接种对象为年龄从1至15岁的儿童，人数超过930万人。共报告了65例严重不良事件病例，其中22人死亡。绝大部分严重不良事件被认为与疫苗无关。发现2起免疫接种后类脑炎综合征聚集病例，一起可能是自然的乙型脑炎聚集病例，而另一起列为不明病因的急性脑病综合征，但没有对其他可能的病因开展彻底的调查。
委员会认为报告的不良事件总数相对于目标人群来说很低，而脑病和脑炎病例聚集发生这种类型看来又不大可能与疫苗有关。但是对严重不良事件更好地加以定义，采用标准病例分类方法，如“布赖顿协作计划”（the Brighton Collaboration）的定义，更积极主动地开展调查工作是有价值的。GACVS建议今后开展强化免疫时应该同时加强AEFI监测和病历调查工作。
肺炎球菌结合疫苗的安全性
应免疫战略咨询专家组(SAGE)要求，委员会评审了肺炎球菌结合疫苗的安全性。会议期间完成并介绍了有关肺炎球菌结合疫苗安全性所有证据的综合性评述。资料来源于62项研究，包括随机对照试验和上市后研究。虽然在一些研究中出现不明显的和无规律的呼吸道反应增多的迹象，但这些明显的影响并不具有普遍性。
关于7价肺炎球菌结合疫苗和其他肺炎球菌结合疫苗的安全性证据是可靠的。自从2000年7价肺炎球菌结合疫苗获准上市以来，在美国得到广泛使用，最近在加拿大和一些欧洲国家使用，没有发现任何重要安全问题的报告。有大量证据表明，如发展中国家引进疫苗，目前可获得的肺炎球菌结合疫苗将会对肺炎球菌疾病和总的婴儿死亡率有显著影响。但是正如引进任何新疫苗一样，为发现可能是罕见的和意想不到的影响，开展监测工作十分重要。
委员会的运作模式和其他信息
除在《疫情周报》发表之外，委员会的工作范围及其既往决议、建议和行动及委员会的运作模式已发表于《美国公共卫生杂志》7。更多关于本文中讨论的问题和委员会的职责的信息可参阅GACVS网站：http://www./vaccine_safety/en/。委员会同意在下一次2007年6月的会议上将进一步讨论疫苗配方的安全性问题和更新关于人乳头瘤病毒疫苗和轮状病毒疫苗安全性的综述。
1 见WER No. 41, 1999, pp.337-338。
2 GACVS邀请了其他专家提出证据并参加有关腮腺炎疫苗毒株、在印度使用的流行性乙型脑炎疫苗的安全性、青少年和年轻人的疫苗接种包括与安全性评估有关的偶合病状问题以及肺炎球菌结合疫苗的安全性审议的讨论。
3 见WER No. 28, 2005, pp. 242–247。
4 见WER No. 28, 2006, pp. 273–278。
5 见WER No. 32, 2003, pp 282–284。
6 见WER No. 2, 2006, pp. 15–18。
7 A global perspective on vaccine safety and public health: the Global Advisory Committee on Vaccine Safety. American Journal of Public Health, 2004, 94:1926-1931.
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Global Advisory Committee on Vaccine Safety, 29-30 November 2006
The Global Advisory Committee on Vaccine Safety (GACVS), an expert clinical and scientific advisory body, was established by WHO to deal with vaccine safety issues of potential global importance independently from WHO and with scientific rigour.1 GACVS held its fifteenth meeting in Geneva, Switzerland, on 29–30 November 2006.2 The committee discussed a number of general issues relevant to all vaccines as well as a number of vaccine-specific issues. Discussions of vaccine-specific issues pertained both to long-standing vaccines as well as to new vaccines or vaccines still under development. The following issues, among others, were considered.
General issues
Monitoring vaccine safety
At previous meetings3, 4, the GACVS requested that global vaccine pharmacovigilance be strengthened, particularly within the context of the WHO Programme for International Drug Monitoring. Aspects in particular need of attention include data transmission by countries, assurance of data quality, and the processing and analysis of data, including timely signal detection and action. As a result of the above-mentioned request, a subgroup of 6 GACVS members was formed to work closely with the secretariat to ensure that the initiative continues to move forward in a timely fashion.4 A report of the subgroup’s activities was presented to the full committee. The specific terms of reference of this subgroup are: to advise WHO regarding the development of a high-quality system for reporting, detecting, analysing and communicating adverse events following immunization (AEFI) at a global level; and to advise WHO, the WHO Collaborating Centre for International Drug Monitoring based in Uppsala, Sweden, (known as the Uppsala Monitoring Centre or UMC) and Member States on specific issues relating to implementing activities aimed at achieving the first goal. To achieve this goal, specific objectives and deliverables have been agreed upon, and these will be undertaken by the subgroup over the next couple of years. A high priority will be to raise the profile and awareness of pharmacovigilance within the immunization community using existing WHO networks and other means.
A report on a visit to Uppsala by representatives of the secretariat and subgroup was presented. Key areas for action include: (i) increasing vaccine-specific expertise at the UMC through the creation of a position dedicated to vaccine safety; (ii) assisting in the recruitment of additional volunteer expert reviewers who can assess potential vaccine safety signals; and (iii) engaging scientific experts to consider what types of methods are best for detecting vaccine safety signals. Deficiencies with respect to vaccines in the anatomical therapeutic chemical and defined daily dose (ATC/DDD) classification and WHO’s Drug Dictionary need to be addressed. A programme of work is planned to review and propose modifications appropriate to vaccines to the ATC/DDD; these proposals will be presented to the WHO Collaborating Centre for Drug Statistics Methodology, Oslo, Norway, at its forthcoming meeting.
Report of the WHO Expert Committee on Biological Standardization
The work of the WHO Expert Committee on Biological Standardization was summarized. The committee establishes global norms and standards that help define biological medicinal products of assured quality, including the quality, efficacy and safety specifications that are used for prequalification of vaccines.
The committee met most recently during 23–27 October 2006. At that meeting, 3 new written standards were established: for human papillomavirus vaccines, for meningococcal A conjugate vaccine, and for the regulatory expectations for stability evaluations of vaccines. The committee also established 15 new reference preparations, which are global measurement standards that guide manufacturers and regulatory authorities on the activity of biological medicines. Finally, the committee endorsed a number of new projects in the area of quality standards and commented on a number of regulatory issues, including regulatory preparedness for pandemic influenza vaccines and the licensing of vaccines procured through United Nations agencies.
During discussion of the committee’s report, GACVS noted that developing processes to share safety information from clinical trials of vaccines would be beneficial and requested that the secretariat explore ways to do this.
Safety of vaccine formulations
This session stemmed from a recommendation made at the last GACVS meeting that the committee should start looking proactively into the real and perceived safety of preservatives and other inactive ingredients in vaccine formulations. The limited information provided about excipients, in contrast to the active components, in vaccines was highlighted. This is a challenge for drug regulators and industry in the areas of quality assurance, and it is likewise a challenge for health professionals in terms of communicating risks. The infrequent administration of vaccines makes it unlikely that small amounts of excipients are toxic. However, this may change with the development of therapeutic vaccines, which might be administered repeatedly. A mechanism must be established to secure more information about detailed vaccine formulations and to rigorously review the safety of excipients.
A GACVS subgroup was established to examine this issue in further detail. The subgroup will report on its work, including identifying priorities and establishing a listing of excipients and conceivable adverse effects, at the June 2007 meeting of the committee.
Vaccinating adolescents and young adults: problems with coincidental pathologies and safety assessments
There is likely to be an increased focus on the vaccination of adolescents both for new vaccines, such as human papillomavirus vaccines, and for some previously available vaccines. The committee was presented with preliminary modelling work performed using health utilization data from a health maintenance organization (a type of private health insurer) in the United States. This work indicates there is a high likelihood of the coincidental occurrence of various pathologies in close proximity to vaccinations. This is especially the case for gynaecological and autoimmune disorders, and such observations may lead to public concern about vaccine safety. The committee recognized that this issue deserves more attention. Countries moving towards introducing vaccines aimed at adolescents and young adults should endeavour to secure population-specific and age-specific baseline rates of specific conditions in the relevant age-group (for example, rates of autoimmune disease). This will assist any investigation of safety issues that may surface. Any signal generated by surveillance will require thorough investigation using appropriate epidemiological methods before conclusions can be drawn.
Issues associated with specific vaccines
Safety of mumps vaccine strains
At the request of the immunization Strategic Advisory Group of Experts (SAGE), the committee was asked to update the 2003 comprehensive review of the safety of mumps vaccine strains, paying particular attention to the risk of vaccine-derived meningitis. A review of the safety profile based on an updated literature search and data provided by some vaccine manufacturers was presented to the committee.
Similar to its previous review,5 GACVS noted that cases of aseptic meningitis and estimates of incidence rates have been reported following the use of Urabe, Leningrad–Zagreb, Hoshino, Torii, and Miyahara strains from various surveillance systems and epidemiological studies. Given the variability in the quality of these studies and in the methods used, no clear conclusion on differences in risk between these vaccine strains can be drawn. The data up to now have revealed low rates of aseptic meningitis and no cases of virologically proven meningitis following the use of Jeryl–Lynn and RIT 4385 strains. There is only limited information about the Leningrad-3 strain. No data were available to assess the safety of the S79 strain.
Mass vaccination campaigns using mumps–measles–rubella vaccine that contained mumps vaccine strains associated with an increased risk of aseptic meningitis have resulted in clusters of adverse events that disrupted programmes. Recognition of the clustering of cases of aseptic meningitis has potentially been enhanced during mass immunization campaigns due to increased sensitivity of AEFI surveillance. This has been observed with Urabe and Leningrad–Zagreb strains. As of the date of this meeting, all reported cases of vaccine-derived mumps meningitis have recovered. Some of these were laboratory diagnosed cases and had little, if any, clinically significant disease. Despite the occurrence of these cases, the perceived risk–benefit ratio of utilization of the Urabe and Leningrad–Zagreb mumps vaccines over several years in routine programmes in developing countries has been considered acceptable. However, if mumps vaccine strains that have been associated with an increased risk of aseptic meningitis are to be used in mass campaigns, immunization programmes should implement appropriate strategies for communicating risk and managing cases in order to handle possible reports of clusters of aseptic meningitis.
Further studies undertaken to compare the safety profile of different mumps vaccine strains should be carefully designed to discriminate between potential strain variability and age-specific risk in different populations. Standardization of case definitions and quantification of severity will help in interpreting results.
GACVS is pleased with the steps taken to establish a repository of mumps vaccine virus strains at the National Institute for Biological Standards and Control, Potters Bar, England, and urges the acceleration of work to gain insight into the biological determinants of risk from the different strains. The committee requests to be informed of any new data pertaining to the safety of mumps vaccines so that a better assessment can be made of the risk of aseptic meningitis or other conditions associated with specific strains.
Safety of BCG vaccine in HIV-infected children
The committee has reviewed the policy on the use of bacille Calmette–Guérin (BCG) vaccination for children infected with HIV in light of new evidence. Data from retrospective studies from Argentina and South Africa indicate there is a substantiated higher risk of disseminated BCG disease developing in children infected with HIV who are vaccinated at birth and who later developed AIDS. The reported risk associated with vaccinating HIV-infected children may outweigh the benefits of preventing severe tuberculosis, especially since the protective effect of BCG against tuberculosis in HIV-infected children is not known.
WHO currently recommends administering a single dose of BCG vaccine to all infants living in areas where tuberculosis is highly endemic as well as to infants and children at particular risk of exposure to tuberculosis in countries with low endemicity. BCG vaccine is contraindicated in people with impaired immunity, and WHO does not recommend BCG vaccination for children with symptomatic HIV infection.
GACVS concluded that the recent findings indicated there is a high risk of disseminated BCG disease developing in HIV-infected infants and therefore BCG vaccine should not be used in children who are known to be HIV infected.
The committee recognizes the difficulty in identifying infants infected with HIV at birth in settings where diagnostic and treatment services for mothers and infants are limited. In such situations, BCG vaccination should continue to be given at birth to all infants regardless of HIV exposure, especially considering the high endemicity of tuberculosis in populations with high HIV prevalence. Close follow up of infants known to be born to HIV-infected mothers and who received BCG at birth is recommended in order to provide early identification and treatment of any BCG-related complication. In settings with adequate HIV services that could allow for early identification and administration of antiretroviral therapy to HIV-infected children, consideration should be given to delaying BCG vaccination in infants born to mothers known to be infected with HIV until these infants are confirmed to be HIV negative.
Update on Menantra® and Guillain-Barré syndrome
An update on the reported occurrence of Guillain-Barré syndrome (GBS) after vaccination with a tetravalent conjugated meningococcal vaccine (Menactra®)6 in the United States was presented. As of September 2006, a total of 17 cases had been reported to the US Vaccine Adverse Event Reporting System as occurring within 6 weeks after vaccination. Analysis of the data suggests that there may be a small increased risk (1.25 cases per million doses distributed; 95% confidence interval, 0.058–5.993) of GBS after vaccination with Menactra®, but this finding should be viewed with caution, given the limitations of the reporting system and the uncertainty regarding background incidence rates of GBS.
Pandemic influenza vaccines
The committee discussed plans for the global monitoring of the safety of pandemic influenza vaccine. The committee emphasized the importance of developing a robust network of contact points to share information and pilot the system during seasonal influenza immunization. The network is intended to ensure that Member States have rapid and timely access to safety information concerning pandemic and seasonal influenza vaccines, to provide access to dedicated resources able to address urgent queries, and to initiate and coordinate relevant responses. A web-based platform to support the collection and dissemination of information to relevant stakeholders in Member States is being developed. The formation of this influenza vaccine safety network should be carefully planned and should consider the possible limitations imposed by the pandemic.
Recognizing that the availability of several global surveillance systems for communicable diseases, drugs or vaccines may be relevant to certain aspects of monitoring the safety of pandemic influenza vaccines, the global post-marketing surveillance network aims to coordinate resources and supplement areas not sufficiently addressed. Although the system is being developed for pandemic influenza vaccines, it would initially use seasonal influenza vaccine safety monitoring as a proxy. A subgroup of GACVS will be formed to pursue this goal in connection with the series of WHO regulatory preparedness workshops on human vaccines for pandemic influenza.
Safety of Japanese encephalitis vaccination in India
GACVS considered the report from an Indian expert panel that assessed the reported cases of serious adverse events following immunization campaigns with the live, attenuated SA 14-14-2 Japanese encephalitis vaccine in 4 Indian states during the summer of 2006. These campaigns reached >9.3 million children aged between 1 year and 15 years. A total of 65 serious adverse events were reported, 22 of which were fatal. Most serious adverse events were considered to be unrelated to the vaccine. A total of 2 clusters of encephalitis-like syndromes were identified after immunization, 1 probably representing cases of natural Japanese encephalitis and another classified as acute encephalopathy syndrome of unknown etiology; thorough investigation into possible alternative etiologies has not been conducted.
The committee considered that the overall number of reported serious adverse events appeared low for the target population and that the type of clustering of encephalopathy and encephalitis cases made it unlikely that they were related to the vaccine. However, a better definition of cases of serious adverse events, using standard case classifications, such as the Brighton Collaboration definitions, and more active case investigation would be valuable. GACVS recommended that future immunization campaigns should be accompanied by strengthened AEFI monitoring and investigation activities.
Safety of pneumococcal conjugate vaccine
At the request of SAGE, the committee reviewed the safety of pneumococcal conjugate vaccines. A comprehensive review of all evidence on the safety of pneumococcal conjugate vaccines was conducted and presented. Data from 62 studies, including randomized controlled trials and post-marketing studies, were included in the review. While there has been a weak and inconsistent signal of increases in reactive airway conditions in some studies, these apparent effects have not been consistently observed.
The evidence on the safety of the 7-valent pneumococcal conjugate vaccine and other pneumococcal conjugate vaccines is reassuring. Reports since the licensure of the 7-valent pneumococcal conjugate vaccine in 2000 and widespread use in the United States and, more recently, in Canada and some European countries, have not identified any major safety concerns. There is substantial evidence that when introduced into developing countries, the presently available pneumococcal conjugate vaccines will have a considerable impact on pneumococcal disease and overall infant mortality. Nevertheless, as with the introduction of any new vaccine, it will be important to conduct surveillance for possible rare and unexpected effects.
Modus operandi of the committee and additional information
In addition to publications in the Weekly Epidemiological Record, the scope of the committee’s work and past decisions, recommendations and actions, as well as its modus operandi, have been published in the American Journal of Public Health.7 More information about the topics discussed in this article as well as the committee’s terms of reference can be found on the GACVS web site at http://www./vaccine_safety/en/. The committee agreed to discuss further the safety of vaccine formulations and to update its review of the safety of human papillomavirus and rotavirus vaccines at its next meeting in June 2007.
- See No. 41, 1999, pp.337-338
- GACVS invited additional experts to present evidence and participate in the discussions on the safety of mumps vaccine strains, the safety of Japanese encephalitis vaccine in India, the vaccination of adolescents and young adults including problems associated with coincidental pathologies in terms of safety assessments, and the review of safety of conjugate pneumococcal vaccine.
- See No. 28, 2005, pp. 242–247.
- See No. 28, 2006, pp. 273–278.
- See No. 32, 2003, pp 282–284.
- See No. 2, 2006, pp. 15–18.
- A global perspective on vaccine safety and public health: the Global Advisory Committee on Vaccine Safety. American Journal of Public Health, 2004, 94:1926-1931.
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3、性传播感染 Sexually transmitted infections
性传播感染是主要通过人与人的性接触而传播的感染。有30多种不同的性传播细菌、病毒和寄生虫。
最常见的性传播感染包括淋病，衣原体感染，梅毒，滴虫病，软下疳，生殖器疱疹，尖锐湿疣，人类免疫缺陷病毒(艾滋病毒)感染和乙型肝炎感染。
其中一些，尤其是艾滋病毒和梅毒，还可能在妊娠和生育期间由母亲传播给孩子，并可通过血液制品和组织移植来传播。
Sexually transmitted infections (STIs) are infections that are spread primarily through person-to-person sexual contact. There are more than 30 different sexually transmissible bacteria, viruses and parasites.
The most common conditions they cause are gonorrhoea, chlamydial infection, syphilis, trichomoniasis, chancroid, genital herpes, genital warts, human immunodeficiency virus (HIV) infection and hepatitis B infection.
Several, in particular HIV and syphilis, can also be transmitted from mother to child during pregnancy and childbirth, and through blood products and tissue transfer.
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