关键词： polio   immunization   individual-based model   disease outbreaks   heterogeneity  

摘要： Background. Pockets of undervaccinated individuals continue to raise concerns about their potential to sustain epidemic transmission of vaccine-preventable diseases. Prior importations of live polioviruses (LPVs) into Amish communities in North America led to their recognition as a potential and identifiable linked network of undervaccinated individuals. *** integral We developed an individual-based model to explore the potential transmission of a LPV throughout the North American Amish population. *** integral Our model demonstrates the expected limited impact associated with the historical importations, which occurred in isolated communities during the low season for poliovirus transmission. We show that some conditions could potentially lead to wider circulation of LPVs and cases of paralytic polio in Amish communities if an importation occurred during or after 2013. The impact will depend on the uncertain historical immunity to poliovirus infection among members of the community. *** integral Heterogeneity in immunization coverage represents a risk factor for potential outbreaks of polio if introduction of a LPV occurs, although overall high population immunity in North America suggests that transmission would remain relatively limited. Efforts to prevent spread between Amish church districts with any feasible measures may offer the best opportunity to contain an outbreak and limit its size.

关键词： 脊髓灰质炎/预防和控制   疾病清除   疾病爆发流行/预防和控制   群体免疫接种   脊髓灰质炎病毒   人口监测   危险性评估  

摘要： 大连市通过加强脊髓灰质炎疫苗常规免疫和开展补充免疫活动,以及加强急性迟缓性麻痹(acute flaccid paralysis,AFP)病例监测,连续23年维持无脊髓灰质炎(以下简称脊灰)状态。但现阶段大连市维持无脊灰仍面临着挑战:随时存在脊灰野病毒(wild poliovirus,WPV)输入风险,有机会发生疫苗相关麻痹型脊灰病例。为继续维持无脊灰状态,直至全球消灭脊灰,大连市要继续按照国家要求,加强常规免疫,保持高水平AFP病例监测质量以及随时做好WPV输入的应急准备。

关键词： polio   eradication   dynamic modeling   disease outbreaks   inactivated poliovirus vaccine   oral poliovirus vaccine  

摘要： Background. The Global Polio Eradication Initiative plans to stop all oral poliovirus vaccine (OPV) after wild poliovirus eradication, starting with serotype 2. Stakeholders continue to discuss the role of using inactivated poliovirus vaccine (IPV) to manage the risks of circulating vaccine-derived polioviruses (cVDPVs) during the end game. *** integral We use a poliovirus transmission and OPV evolution model to explore the impact of various routine immunization policies involving IPV on population immunity dynamics and the probability and magnitude of cVDPV emergences following OPV cessation. *** integral Adding a single IPV dose to an OPV-only routine immunization schedule at or just before OPV cessation produces very limited impact on the probability of cVDPV emergences and the number of expected polio cases in settings in which we expect cVDPVs in the absence of IPV use. The highest-cost option of switching to a 3-dose IPV schedule only marginally decreases cVDPV risks. Discontinuing supplemental immunization activities while introducing IPV prior to OPV cessation leads to an increase in cVDPV risks. *** integral Introducing a dose of IPV in countries currently using OPV only for routine immunization offers protection from paralysis to successfully vaccinated recipients, but it does little to protect high-risk populations from cVDPV risks.

关键词： polio eradication   dynamic modeling   disease outbreaks   oral poliovirus vaccine  

摘要： Background. Oral poliovirus vaccine (OPV) results in an ongoing burden of poliomyelitis due to vaccine-associated paralytic poliomyelitis and circulating vaccine-derived polioviruses (cVDPVs). This motivates globally coordinated OPV cessation after wild poliovirus eradication. *** integral We modeled poliovirus transmission and OPV evolution to characterize the interaction between population immunity, OPV-related virus prevalence, and the emergence of cVDPVs after OPV cessation. We explored strategies to prevent and manage cVDPVs for countries that currently use OPV for immunization and characterized cVDPV emergence risks and OPV use for outbreak response. *** integral Continued intense supplemental immunization activities until OPV cessation represent the best strategy to prevent cVDPV emergence after OPV cessation in areas with insufficient routine immunization coverage. Policy makers must actively manage population immunity before OPV cessation to prevent cVDPVs and aggressively respond if prevention fails. Sufficiently aggressive response with OPV to interrupt transmission of the cVDPV outbreak virus will lead to die-out of OPV-related viruses used for response in the outbreak population. Further analyses should consider the risk of exportation to other populations of the outbreak virus and any OPV used for outbreak response. *** integral OPV cessation can successfully eliminate all circulating live polioviruses in a population. The polio end game requires active risk management.

关键词： inactivated poliovirus vaccine   polio eradication   polio   routine immunization  

摘要： Background. The Strategic Advisory Group of Experts on Immunization (SAGE) has recommended introduction of at least 1 dose of inactivated poliovirus vaccine (IPV) at >= 14 weeks of age through the routine immunization program in countries currently not using IPV. *** integral We analyzed all available unrestricted data obtained from the Demographic and Health Surveys since 2005 in sub-Saharan Africa (31 countries) and in South and Southeast Asia (9 countries) to determine coverage of the following injectable vaccines delivered through the routine immunization schedule: diphtheria-tetanus-pertussis vaccine dose 1 (DTP1), DTP2, DTP3, and measles vaccine. Coverage with these vaccines was used as a proxy measure of likely 1- and 2-dose IPV coverage. *** integral Coverage with 1 dose of IPV is expected to be lowest when offered with DTP3 (median coverage, 73%) and highest when offered with DTP1 (median coverage, 90%). The median DTP1-DTP3 drop-out rate was 14%, which equates to an additional 12 million children not receiving IPV if IPV is offered with DTP3, rather than with DTP1. An increased geographical clustering of children who have not received IPV is expected in sub-Saharan Africa and Asia if IPV is offered with DTP3, rather than with DTP1. Coverage with 2 doses of IPV is expected to be lowest if IPV is administered with DTP3 and measles vaccine (69%) and highest if administered with DTP1 and DTP2 (84%). *** integral Coverage with 1 dose of IPV is expected to be lowest if it is administered at the DTP3 visit. At present, there is insufficient evidence to determine whether the SAGE-recommended IPV schedule for the polio endgame would maximize population immunity to type 2 poliovirus.

关键词： polio   eradication   population immunity   OPV   IPV  

摘要： Background. India presented many challenges to the global effort to eliminate the transmission of wild polioviruses (WPVs) and poliomyelitis, with the last case of WPV type 2 in the world reported in northern India in 1999 and WPV types 1 and 3 circulating until early 2011. *** integral We used a differential equation-based model to characterize the dynamics of poliovirus transmission and various opportunities to increase and maintain high population immunity to poliovirus transmission for 2 high-risk areas in northern India. We explored options that India probably considered before 2011, to demonstrate the impact of strategies to accelerate WPV elimination and sustain high population immunity. We also characterized the impact of current and potential future vaccination strategies and explored the potential trade-offs associated with the various strategies. *** integral National immunization policy choices impact population immunity, which leads to different numbers of expected paralytic cases and risks of circulating vaccine-derived poliovirus outbreaks. Assuming that India maintains high vaccination intensity everywhere, we do not anticipate issues with outbreaks of circulating vaccine-derived poliovirus type 2 infection following globally coordinated cessation of type 2-containting oral poliovirus vaccine use. We find a relatively modest potential role for inactivated poliovirus vaccine. *** integral National policy makers should consider the impacts of their vaccine choices on population immunity to poliovirus transmission.

关键词： seroprevalence   wild poliovirus   vaccination strategy   oral polio vaccine   immunization campaigns  

摘要： Background. Despite intensified use of monovalent oral poliovirus type 1 vaccine and improved coverage of immunization campaigns, wild poliovirus type 1 persisted in Indian states of Uttar Pradesh and Bihar during 2006 to 2009. *** integral A serosurvey was conducted among cases of acute flaccid paralysis in the 25 high-polio-incidence districts of western Uttar Pradesh. Children were recruited by age group (6-11 months, 12-24 months, and 25-69 months) from among cases reported through the acute flaccid paralysis surveillance system between November 2008 and August 2009. *** integral Seroprevalence for type 1 wild poliovirus was > 96.4% for each age group. The seroprevalence of wild poliovirus types 2 and 3 increased with age, from 36.7% to 73.4% for type 2 and from 39.0% to 74.1% for type 3. In addition to the number of type-specific vaccine doses, father's level of education, being from a Muslim family, height for age, and female sex were the socioeconomic risk factors associated with seronegativity to poliovirus. *** integral The seroprevalence and risk factors identified in this study were consistent with the epidemiology of polio, and the findings were instrumental in optimizing vaccination strategy in western Uttar Pradesh with respect to the choice of OPV types, the frequency of supplementary immunization campaigns, and the urgency to improve routine immunization services.

关键词： poliovirus excretion   primary immune deficiency   vaccine-derived polioviruses   OPV  

摘要： Background. Persons with primary immune deficiency disorders (PID), especially those disorders affecting the B-cell system, are at substantially increased risk of paralytic poliomyelitis and can excrete poliovirus chronically. However, the risk of prolonged or chronic excretion is not well characterized in developing countries. We present a summary of a country study series on poliovirus excretion among PID cases. *** integral Cases with PID from participating institutions were enrolled during the first year and after obtaining informed consent were tested for polioviruses in stool samples. Those cases excreting poliovirus were followed on a monthly basis during the second year until 2 negative stool samples were obtained. *** integral A total of 562 cases were enrolled in Bangladesh, China, Iran, Philippines, Russia, Sri Lanka, and Tunisia during 2008-2013. Of these, 17 (3%) shed poliovirus, including 2 cases with immunodeficient vaccine-derived poliovirus. Poliovirus was detected in a single sample from 5/17 (29%) cases. One case excreted for more than 6 months. None of the cases developed paralysis during the study period. *** integral Chronic polioviruses excretion remains a rare event even among individuals with PID. Nevertheless, because these individuals were not paralyzed they would have been missed by current surveillance;therefore, surveillance for polioviruses among PID should be established.

关键词： poliovirus   polio eradication   laboratory containment   polio endgame   OPV cessation  

摘要： Background. The first steps (phase 1) toward laboratory containment of poliovirus after eradication are a national survey of biomedical facilities and a global inventory of such facilities retaining wild poliovirus (WPV) infectious and potentially infectious materials. *** integral We reviewed published reports on national laboratory surveys and inventories of WPV materials from each of the 3 polio-free World Health Organization (WHO) regions (the European Region, completed in 2006;the Western Pacific Region, completed in 2008;and the Region of the Americas, completed in 2010), as well as reports on progress in polio-free countries of the remaining 3 regions (the African Region, the Eastern Mediterranean Region, and the WHO South-East Asia Region). *** integral Containment phase 1 activities are complete in 154 of 194 WHO Member States (79%), including all countries and areas of the polio-free regions and most polio-free countries in the remaining 3 regions. A reported 227 209 biomedical facilities were surveyed, with 532 facilities in 45 countries identified as retaining WPV-associated infectious or potentially infectious materials. *** integral Completion of containment phase 1 global activities is achievable within the time frame set by the Polio Eradication and Endgame Strategic Plan 2013-2018.

关键词： 脊髓灰质炎,麻痹型   疫苗  

摘要： 患儿，男，2013年6月2日出生，散居。患儿为足月产儿，出生后健康，无药物过敏史，无家族史及既往病史，服OPV前精神状况均较好。患儿自出生至发病以来，均未曾到过外地，无外来人口接触史；无与其他麻痹患者和服苗患者的接触史。患儿于2013年8月21日即2月龄首次服用口服脊灰减毒活疫苗（ OPV ）后发病。本乡和临乡以及患儿所在县的各级各类医疗机构开展了AFP病例的主动搜索，未发现15岁以下出现麻痹症状儿童。临床表现：9月5日出现发热，就诊于卫生院，给予口服药物治疗。9月8日，出现肢体麻痹。于9月11日到河北省儿童医院就诊，查体：右上肢肌力肌张力正常，桡骨膜反射及肱二头肌反射存在，痛觉存在，温觉查体不配合；左上肢肌力Ⅱ级，肌张力减低，桡骨膜反射及肱二头肌反射减弱；双下肢肌力Ⅱ级，肌张力减低，双膝、跟腱反射未引出，痛觉存在，温觉查体不配合；双巴氏征、克氏征、布氏症阴性。辅助检查：脑脊液：白细胞25×106／L，单核细胞21×106／L，多核细胞4×106／L，葡萄糖2．29 mmol／L，蛋白0．40 g／L。肌电图：双侧腓总神经、左正中神经、尺神经运动神经传导CMAP波幅减低，双侧胫前肌、股四头肌、三角肌、左侧外展拇短肌机电图示神经源性损害。诊断为脊髓炎、上呼吸道感染、肛瘘，入院治疗并进行康复训练。9月28日出院，右上肢肌力肌张力正常，左上肢肌力Ⅳ级，肌张力基本正常，双桡骨膜反射及肱二头肌反射可引出；双下肢肌力Ⅱ级，肌张力减低，双膝、跟腱反射未引出，双巴氏征、克氏征、布氏症阴性。实验室检测结果：2013年9月13、14日采集患儿双份合格便标本，经省CDC脊灰实验室检验，分离出Ⅰ型病毒，10月16日送国家脊灰实验室进一步鉴定，检测结果为Ⅰ型病毒VP1区核苷酸序列变异数为6个。10月22日采集患儿所在村7名接触者便送省CDC脊灰实验室检验，均为阴性。10月22日、11月6日分别采集患儿第3、4份粪便标本送省脊灰实验室，均为阴性。诊断结果及依据启动了市、县两级预防接种异常反应调查诊断专家组，根据该病例的流行病学调查结果和临床资料，按照《疫苗相关麻痹型脊髓灰质炎病例诊断依据及治疗参考意见》，专家组认定该患儿符合脊灰疫苗相关病例诊断依据。患儿的麻痹症状均较发病初期有一定好转，但均留有残留性麻痹。其中，患儿左上肢和右上肢肌力为3级，右上肢肌力4级，左下肢肌力2级，跟腱反射、膝反射减弱。