消灭脊髓灰质炎行动现状分析及免疫策略建议

脊髓灰质炎曾在全球广泛流行和传播,严重危害儿童健康。自1988年世界卫生大会发起全球消灭脊髓灰质炎行动倡议以来,全球脊髓灰质炎防控工作取得显著进展,但消灭脊髓灰质炎工作仍面临重重挑战。在目前维持无脊髓灰质炎状态下,我国面临的主要问题是疫苗相关麻痹型脊髓灰质炎(vaccine associated paralytic poliomyelitis, VAPP)病例和脊髓灰质炎疫苗衍生病毒(vaccine-derived poliovirus,VDPV)病例的发生。为此,通过回顾消灭脊髓灰质炎工作取得的进展,总结不同国家或地区在消灭脊髓灰质炎过程中所采用的防控策略,尤其是不同国家或地区的脊髓灰质炎疫苗使用经验,分析消灭脊髓灰质炎最后阶段面临的挑战,进而提出应对策略和建议,即科学评价防控措施、适时调整脊髓灰质炎免疫策略、努力消除接种犹豫并提高疫苗接种率,这对早日实现根除脊髓灰质炎的目标是非常有必要的。     

深圳市2005—2012年脊髓灰质炎疫苗相关病例流行病学分析

目的了解深圳市脊髓灰质炎疫苗相关病例(VAPP)发生情况及流行病学特征,为消灭脊髓灰质炎后期脊灰疫苗免疫策略的研究提供基础数据。方法采用流行病学方法对深圳市2005—2012年残留麻痹急性弛缓性麻痹AFP病例个案资料、病原学检测结果、VAPP病例进行分析。结果 2005—2012年共报告残留麻痹病例55例,其中VAPP病例8例,占15.54%;深圳市VAPP病例均为小年龄组小于6月龄的儿童,总发生率0.20/10万,无接触者VAPP病例,其中首次服苗的VAPP发生率为0.51/10万;无明显的地区和时间分布聚集性。结论 VAPP的发生是接种脊髓灰质炎减毒活疫苗难以克服的弱点,为减少VAPP病例及防止脊灰疫苗衍生病毒的发生,应在消灭脊髓灰质炎后期科学、合理地调整消灭脊髓灰质炎的免疫策略。     

单克隆抗体在波兰1981-1990年脊髓灰质炎病毒学和流行病学回顾中的应用

<正>1988年世界卫生大会采纳了2000年全球消灭脊髓灰质炎(简称脊灰)的目标。一个国家消灭脊灰分四个阶段,假设达到了消除脊灰的阶段(如有可靠的报告系统三年无本地病例,脊灰免疫复盖率达80％以上),必须努力追踪与脊灰野病毒有关的每一可能病例。在此情况下,每例病人都应有实验支持,包括型别鉴定,各株的型内特征,以及与疫苗株和原野毒株(本地或输入)的关系。     

野病毒传播阻断后麻痹型脊灰危险的评价

1988年,WHO成员国卫生部长参加的世界卫生大会提出全球消灭脊髓灰质炎(脊灰)的目标。到2002年末,全球216个国家和地区中,209个阻断了本土脊灰野病毒的传播,目前,脊灰已接近消灭,国际上已把注意力集中到政策制定上。     

现阶段脊髓灰质炎流行病学特征及防治对策

<正>脊髓灰质炎(以下简称Polio)是一种古老的急性病毒性传染病,在发展中国家是一个重要的公共卫生问题。1840年Heine首次描述了本病的临床表现。1890年Medin第一次报告了本病的流行。二十世纪初叶已在欧洲、美洲十几个国家流行。二次大战后有更多的国家发生了流行。我国有记载的最早1例发生于1882年,1938年有人搜集各地统计资料后指出,有14个省发生过散在病例。1948及1950年上海发生小流行。我国从1955年开始将本病列为法定传染病,随着疫情报告制度的逐步完善,病例数亦逐年增多。     

1980-2010年鄱阳湖地区土地覆盖与景观格局变化

以1980、2005和2010年鄱阳湖地区的土地覆盖数据为基础,采用GIS、RS及景观生态学的方法,分析1980-2010年该区土地覆盖及景观格局变化情况,并定量分析了土地覆盖类型变化度、斑块面积指数、斑块形状指数、边缘密度指数以及多样性指数等指标,结果表明:1980-2010年,研究区水田、内陆水体、常绿阔叶林和城镇建设用地不仅是该区域的主要土地覆盖类型,而且变化最强烈.总体上,内陆水体、城镇建设用地面积显著增加,水田和旱地面积有所减少.从景观格局变化来看,虽然鄱阳湖地区受到人口增长和经济发展的影响,其景观破碎度变化和景观多样性指数略呈下降趋势,但变化并不大,这反映出前期环境管理对于区域环境保护已经发挥重要作用,但仍然面临长期挑战.     

脊髓灰质炎疫苗研究进展

脊髓灰质炎是由脊髓灰质炎病毒感染所引起的疾病,只能以接种疫苗进行预防。口服脊髓灰质炎疫苗已大幅度降低了全球脊髓灰质炎的发病率,然而,由于疫苗相关麻痹型脊灰和疫苗衍生脊髓灰质炎病毒风险的出现,今后必须停止使用口服脊髓灰质炎疫苗,以彻底根除脊髓灰质炎。消灭脊髓灰质炎野病毒之后,将会严格管理来源于野毒株的传统脊髓灰质炎灭活疫苗生产,而用Sab in株研制的脊髓灰质炎灭活疫苗抗原性及免疫原性与传统脊髓灰质炎灭活疫苗不同。脊髓灰质炎病毒样颗粒可能成为一种可开发的脊髓灰质炎疫苗。     

天花和种痘

<正>世界上最后一次天花病例报告是于1977年10月在索马里。(1978年在英国伯明翰2个实验室感染的病例暂且不论)。1979年12月全球扑灭天花证实委员会宣布世界上已消灭了天花,此项声明在1980年5月8日被33届WHO年会正式批准。     

口服脊髓灰质炎疫苗的安全性:WHO的一项调查结果

<正> 为获得可能与使用口服脊髓灰质炎疫苗(OPV有关的危险性和采取措施降低这种危险性的资料。WHO于1969年组织了一项协作研究。最初五年和十年的研究结果以前已作报道,本文报告 1980～84年的结果。有13个国家为最后五年提供了关于麻痹型病例及免疫接种的资料。     

1980-2010年鄱阳湖地区土地覆盖与景观格局变化

以1980、2005和2010年鄱阳湖地区的土地覆盖数据为基础,采用GIS、RS及景观生态学的方法,分析1980-2010年该区土地覆盖及景观格局变化情况,并定量分析了土地覆盖类型变化度、斑块面积指数、斑块形状指数、边缘密度指数以及多样性指数等指标.结果表明：1980-2010年,研究区水田、内陆水体、常绿阔叶林和城镇建设用地不仅是该区域的主要土地覆盖类型,而且变化最强烈.总体上,内陆水体、城镇建设用地面积显著增加,水田和旱地面积有所减少.从景观格局变化来看,虽然鄱阳湖地区受到人口增长和经济发展的影响,其景观破碎度变化和景观多样性指数略呈下降趋势,但变化并不大,这反映出前期环境管理对于区域环境保护已经发挥重要作用,但仍然面临长期挑战.     

A vision of a world without polio: the OPV cessation strategy.

Once the eradication of wild poliovirus has been confirmed, the public health benefits of routine immunization with OPV will no longer outweigh the burden of disease either due to paralysis caused by OPV (vaccine associated paralytic polio), or by outbreaks caused by circulating vaccine-derived polioviruses. The eventual cessation of OPV use in routine immunization programmes worldwide will become necessary to assure a lasting eradication of polio. As the world moves towards polio eradication and its certification, preparations are therefore being intensified for OPV cessation, and the risk management framework for safe OPV cessation is being put in place. The framework includes bio-containment of all known poliovirus and potentially infected substances, development of an international stockpile of oral polio vaccine, ensuring a mechanism for continued global surveillance and response for polio after eradication has been certified, and national policies if countries decide to continue vaccinating with inactivated polio vaccine (IPV). It is ironic that the vaccine on which the world has depended for polio eradication will itself become a risk to eradication once the transmission of wild poliovirus has been interrupted. Final preparations for the eventual global and simultaneous cessation of OPV will require the same level of international cooperation and coordination that has brought the world to the verge of polio eradication.     

Unraveling the Transmission Ecology of Polio

Sustained and coordinated vaccination efforts have brought polio eradication within reach. Anticipating the eradication of wild poliovirus (WPV) and the subsequent challenges in preventing its re-emergence, we look to the past to identify why polio rose to epidemic levels in the mid-20th century, and how WPV persisted over large geographic scales. We analyzed an extensive epidemiological dataset, spanning the 1930s to the 1950s and spatially replicated across each state in the United States, to glean insight into the drivers of polio’s historical expansion and the ecological mode of its persistence prior to vaccine introduction. We document a latitudinal gradient in polio’s seasonality. Additionally, we fitted and validated mechanistic transmission models to data from each US state independently. The fitted models revealed that: (1) polio persistence was the product of a dynamic mosaic of source and sink populations; (2) geographic heterogeneity of seasonal transmission conditions account for the latitudinal structure of polio epidemics; (3) contrary to the prevailing “disease of development” hypothesis, our analyses demonstrate that polio’s historical expansion was straightforwardly explained by demographic trends rather than improvements in sanitation and hygiene; and (4) the absence of clinical disease is not a reliable indicator of polio transmission, because widespread polio transmission was likely in the multiyear absence of clinical disease. As the world edges closer to global polio eradication and continues the strategic withdrawal of the Oral Polio Vaccine (OPV), the regular identification of, and rapid response to, these silent chains of transmission is of the utmost importance.     

Polio vaccine: the first 50 years and beyond. Summary of the meeting and next steps.

A conference on "Polio vaccine: the first 50 years and beyond" was held in Toronto, Canada, June 2005. The purpose of the conference was to bring together regulators, manufacturers, academics and public health authorities to celebrate the accomplishments of the past 50 years, to consider the challenges of achieving and sustaining polio eradication and to review standardization and regulatory issues around existing and new polio vaccines. In the final session of the conference the following summary of the meeting was presented.     

Quantifying the Impact of Expanded Age Group Campaigns for Polio Eradication

A priority of the Global Polio Eradication Initiative (GPEI) 2013–2018 strategic plan is to evaluate the potential impact on polio eradication resulting from expanding one or more Supplementary Immunization Activities (SIAs) to children beyond age five-years in polio endemic countries. It has been hypothesized that such expanded age group (EAG) campaigns could accelerate polio eradication by eliminating immunity gaps in older children that may have resulted from past periods of low vaccination coverage. Using an individual-based mathematical model, we quantified the impact of EAG campaigns in terms of probability of elimination, reduction in polio transmission and age stratified immunity levels. The model was specifically calibrated to seroprevalence data from a polio-endemic region: Zaria, Nigeria. We compared the impact of EAG campaigns, which depend only on age, to more targeted interventions which focus on reaching missed populations. We found that EAG campaigns would not significantly improve prospects for polio eradication; the probability of elimination increased by 8% (from 24% at baseline to 32%) when expanding three annual SIAs to 5–14 year old children and by 18% when expanding all six annual SIAs. In contrast, expanding only two of the annual SIAs to target hard-to-reach populations at modest vaccination coverage—representing less than one tenth of additional vaccinations required for the six SIA EAG scenario—increased the probability of elimination by 55%. Implementation of EAG campaigns in polio endemic regions would not improve prospects for eradication. In endemic areas, vaccination campaigns which do not target missed populations will not benefit polio eradication efforts.     

Fatigue and Fear with Shifting Polio Eradication Strategies in India: A Study of Social Resistance to Vaccination

Shifting polio eradication strategies may have generated fear and “resistance” to the eradication program in Aligarh, India during the summer of 2009. Participant observation and formal interviews with 107 people from May to August 2009 indicated that the intensified frequency of vaccination was correlated with patients'' doubt in the efficacy of the vaccine. This doubt was exacerbated in a few cases as families were uninformed of the use of monovalent mOPV1, while P3 cases continued to occur. Many families had also come to believe that their children had been adversely affected by OPV after being told the vaccine carried no risk. Though polio is now largely eradicated in India, with only a single case in 2011, greater transparency about changes with vaccination policy may need to be considered to build trust with the public in future eradication programs.     

Some ethical issues arising from polio eradication programmes in India

The World Health Organisation's programme for the eradication of poliomyelitis as currently practised in India raises many ethical issues. In this paper we concentrate on just two. The first is the balance to be struck between the risks and benefits generated by the eradication programme itself. The issue of risks and benefits arises in relation to the choice between two different vaccine types available for polio programmes: oral polio vaccine (OPV) and inactivated polio vaccine (IPV). OPV is the vaccine currently used in the eradication campaign in India. We argue that given the current risks/benefits profile of this vaccine, there is an urgent need to review the programme and take remedial action to address existing problems (at least in India). The second issue we discuss is the fact that there is little effort to gain the informed consent of the parents of vaccinated children, as they are not currently told about the potential limitations of OPV or the possibility of vaccine-induced harm. We suggest that such a policy might be justifiable, given the importance of polio eradication, but only if there is a system of compensation for vaccine-induced harm as part of the eradication programme itself. There is a real danger that if these issues are not addressed then public trust in the eradication programme and vaccination programmes as a whole will be lost.     

Congo polio immunisation campaign gets go ahead

Since the World Health Organization (WHO) set a goal in 1988 of eradicating polio worldwide by 2000, the incidence of the disease has declined by 90% around the world, with national immunization days conducted in more than 120 countries. More than 450 million children were immunized in 1998 alone. Now, with only about 5000 annual cases of polio occurring, complete eradication can be achieved. To that end, and in a first-ever initiative, the heads of the World Health Organization (WHO) and UNICEF, jointly appealed to UN Secretary General Kofi Annan for help in bringing immunization against polio to children in war-torn Democratic Republic of Congo. Mr. Annan subsequently announced an initiative to negotiate several special ceasefire agreements in Congo so that approximately 10 million children under age 5 years can be immunized against poliomyelitis during July-September 1999. Both the president of Congo, Laurent Kabila, and rebel leaders have given their preliminary assurances that weapons will be laid down while Congolese children are sought out and vaccinated. A joint WHO-UNICEF planning mission will travel to Kinshasa in April to advise the Congolese Ministry of Health, which has main responsibility for the areas under governmental control. The $15 million project is expected to cover 3 rounds of immunization to bring population immunity to the highest possible level.     

Interrupting poliovirus transmission -- new solutions to an old problem.

Since the launch of the Global Polio Eradication Initiative (GPEI) in 1988, knowledge as to the nature of circulating polioviruses and the challenges to their interruption has increased tremendously, particularly during the period 2000-2005. By January 2006, however, the systematic application of the standard polio eradication strategies, combined with recent refinements, had reduced the number of countries with ongoing transmission of indigenous wild polioviruses to just four (Nigeria, India, Pakistan, and Afghanistan), the lowest ever in history. In addition, only 8 of the 22 areas that had been re-infected by wild poliovirus in 2003-2005 still required large-scale 'mop-up' activities and circulating vaccine-derived poliovirus (cVDPV) outbreaks were being readily addressed. This progress, despite new challenges late in the GPEI, was greatly facilitated by a range of solutions that included two new monovalent oral polio vaccines (mOPVs), new and robust international standards for polio outbreak response, and renewed political commitment across the remaining infected countries.