Progress toward poliomyelitis eradication--India, January 2005-June 2006

The global eradication of poliomyelitis has reached a critical stage. The disease remains endemic in only four countries (Afghanistan, India, Nigeria, and Pakistan), which have reported most of the cases in 2006. India is the most populous of the polio-endemic countries. Beginning in 2005, the Government of India (GOI) and its partners intensified eradication efforts by implementing additional immunization and surveillance strategies, including introduction of monovalent oral poliovirus vaccine types 1 and 3 (mOPV1 and mOPV3, respectively). The number of reported cases decreased from 134 in 2004 to 66 in 2005. However, cases have resurged in 2006; as of June 25, 2006, a total of 60 cases had been reported. Although intense local transmission continues in certain areas (i.e., western Uttar Pradesh [UP]), interruption of wild poliovirus (WPV) transmission in India is feasible with continued effective interventions. This report summarizes progress toward polio eradication in India from January 2005 through June 2006.     

Progress toward poliomyelitis eradication---India, January 2010--September 2011

The Global Polio Eradication Initiative was launched in 1988. In 1995, when eradication activities were initiated in India, an estimated 50,000 polio cases were occurring each year. By 2006, transmission of indigenous wild poliovirus (WPV) had been interrupted in all countries except India, Afghanistan, Pakistan, and Nigeria. During 2006--2009, India annually reported 559 to 874 cases of confirmed WPV, with cases centered in the northern states of Uttar Pradesh and Bihar. These cases accounted for 43% of confirmed cases of WPV reported worldwide during this period. However, in 2010, only 42 WPV cases were reported in India, and in 2011, only one WPV case had been confirmed as of October 31. This report updates previous reports and summarizes progress toward polio eradication in India during January 2010--September 2011. Throughout India, the most recent confirmed WPV type 3 (WPV3) case occurred on October 22, 2010, in Jharkhand, and the most recent confirmed WPV type 1 (WPV1) case occurred on January 13, 2011, in West Bengal; WPV2 has not been reported in India since 1999. Importation of WPV into India is a risk, and undetected low-level WPV transmission is a possibility, requiring high vaccination coverage in all states, continued focus on children in migrant and underserved populations, sensitive surveillance for prompt detection of any WPV, and preparedness to mount a robust emergency vaccination campaign in response to any WPV cases.     

Progress toward poliomyelitis eradication --- India, January 2009-October 2010

India is one of only four countries (including Afghanistan, Nigeria, and Pakistan) where wild poliovirus (WPV) transmission has never been interrupted. Historically, WPV transmission in India has centered largely in Uttar Pradesh and Bihar, two states with low routine vaccination coverage, large migrant and remote populations, and lower relative vaccine effectiveness than other areas of the country. However, during a 9-month period from November 2009 to August 2010, no WPV type 1 (WPV1) cases were reported in Uttar Pradesh or Bihar. This report summarizes the substantial progress made in India toward polio eradication during January 2009-October 2010, according to data reported as of December 4, and updates previous reports. During January-October 2010, only 40 WPV cases were confirmed in India, a 94% decrease from the 626 WPV cases confirmed during the same period in 2009; the decrease likely resulted, in large part, from the introduction of bivalent oral poliovirus vaccine types 1 and 3 (bOPV). Increasingly important contributors to WPV transmission are large migrant subpopulations; surveys have indicated that up to 11% of children aged <5 years in these subpopulations were missed during supplementary immunization activities (SIAs). Interruption of all WPV transmission in India will require maintaining high levels of immunity in Uttar Pradesh and Bihar and additional efforts directed toward children in migrant subpopulations that are not vaccinated as readily during SIAs.     

Progress toward poliomyelitis eradication--Pakistan and Afghanistan, 2007

Of the four countries worldwide where wild poliovirus (WPV) transmission has never been interrupted, Pakistan and Afghanistan are considered a single epidemiologic block. Use of intense poliomyelitis eradication measures, including close coordination between the two countries and increased use of monovalent oral poliovirus vaccines (mOPVs) against type 1 WPV (WPV1) and type 3 WPV (WPV3), has reduced WPV transmission to historically low levels. However, despite these efforts, in 2007 both types of WPV continued to circulate in areas of Pakistan and Afghanistan. Ongoing conflicts and security concerns in remote areas with rugged terrain limit access to children and decrease vaccination coverage from routine and supplementary immunization activities (SIAs) in border areas of both countries where WPV transmission is endemic. In other WPV-endemic areas of Pakistan, where security and access concerns do not exist, operational problems in implementing SIAs resulted in inadequate vaccination of children, which failed to interrupt WPV transmission. This report updates previous reports and describes polio eradication activities in Pakistan and Afghanistan during January-December 2007 (data as of March 22, 2008). Further progress toward polio eradication will require continued measures to address security concerns in portions of both countries and problems with implementing SIAs in secure areas of Pakistan.     

Progress toward interruption of wild poliovirus transmission--worldwide, January 2006-May 2007

Progress toward global polio eradication continued during 2006 and the first 5 months of 2007, although the number of countries where wild poliovirus (WPV) transmission has never been interrupted remained at four (Afghanistan, India, Nigeria, and Pakistan). Continuing challenges included intense WPV circulation in northern India during 2006, low vaccination coverage with oral polio vaccine (OPV) during supplemental immunization activities (SIAs) in Nigeria, and security problems preventing access to children during SIAs along the Afghanistan-Pakistan border. Programmatic strategies to address these challenges consisted of large-scale use of type 1 monovalent oral polio vaccine (mOPV1), targeted programs (e.g., cross-border synchronization of polio campaigns) to reach more children through SIAs, and introduction of new laboratory procedures to confirm cases more rapidly. This report summarizes these strategies and overall progress toward global polio eradication.     

Progress toward poliomyelitis eradication--Nigeria, January 2007-August 12, 2008

Nigeria is one of only four countries that have never interrupted poliovirus transmission (the others are Afghanistan, India, and Pakistan). A resurgence in wild poliovirus (WPV) transmission occurred in Nigeria during 2003-2004 after a loss of public confidence in oral poliovirus vaccine (OPV) and suspension of supplementary immunization activities (SIAs)* in several northern states. Subsequently, WPV spread within Nigeria and ultimately into 20 previously polio-free countries during 2003-2006. Even after national SIAs resumed, limited acceptance and ongoing operational problems resulted in low polio vaccination coverage and continued WPV transmission. Beginning in 2006, health authorities in Nigeria introduced new initiatives to control the spread of WPV, including a focus on interrupting type 1 WPV (WPV1) transmission and use of monovalent type 1 OPV (mOPV1) for most of the SIAs to increase vaccine effectiveness. Nigeria also instituted changes in SIA implementation to increase community acceptance of vaccination. Subsequently, 285 polio cases were reported in Nigeria in 2007, the lowest number since sensitive surveillance has been in place. As of August 12, 2008, confirmed polio cases reported in Nigeria totaled 556 (including 511 WPV1 cases), compared with 176 cases (53 WPV1) reported during the same period in 2007. This report updates overall progress toward polio eradication in Nigeria during 2007-2008. Given the increase in WPV transmission thus far in 2008, urgent measures are needed to reach all children during SIAs to bring WPV under control in Nigeria.     

Progress toward poliomyelitis eradication--India, 2003

Since the World Health Assembly resolved in May 1988 to eradicate poliomyelitis, the estimated global incidence of polio has decreased >99%, and three World Health Organization (WHO) regions (Americas, Western Pacific, and European) have been certified as polio-free. Since 1994, when the countries of the WHO South-East Asia Region (SEAR) began accelerating polio-eradication activities, substantial progress toward that goal has been made. By 2001, poliovirus circulation in India had been limited primarily to the two northern states of Uttar Pradesh and Bihar, with 268 cases reported nationwide. However, a major resurgence of polio occurred during 2002, with 1,600 cases detected nationwide, of which 1,363 (85%) were in Uttar Pradesh and Bihar. This report summarizes the status of polio eradication activities in India during 2003 and describes the actions being taken to reduce poliovirus transmission.     

Progress toward poliomyelitis eradication--Nigeria, 2005-2006

Only four countries (Afghanistan, India, Nigeria, and Pakistan) have never experienced interruption of poliovirus transmission. Nigeria had the largest number of cases in 2006, accounting for 1,129 (56%) of the 2,002 cases reported globally. However, major innovations to the national polio-eradication program in Nigeria were initiated in 2006. These innovations, if sustained, should advance the Global Polio Eradication Initiative. Nigeria (2006 population: 140 million) experienced a resurgence in wild poliovirus (WPV) transmission during 2003-2004 after a loss of public confidence in oral polio vaccine (OPV) and suspension of supplementary immunization activities (SIAs) in certain northern states. Subsequently, WPV spread within Nigeria and into 19 polio-free countries. Even after national SIAs recommenced, limited acceptance and ongoing operational problems resulted in low vaccination coverage and continued poliovirus transmission. The number of confirmed polio cases in Nigeria attributed to both WPV type 1 (WPV1) and type 3 (WPV3) increased from 782 in 2004 to 830 in 2005 and to 1,129 in 2006 (as of March 23, 2007). To increase the effectiveness of polio-eradication measures and community acceptance of vaccination, in 2006, health authorities in Nigeria introduced monovalent type 1 OPV (mOPV1) vaccine and changed the way SIAs were implemented. This report summarizes these new approaches and overall progress toward polio eradication in Nigeria during 2005-2006.     

What needs to be done for polio eradication in India?

Even if wild poliovirus persists in one country only, global polio eradication cannot be achieved, because of the risk of exportation of wild virus to other countries. Among the countries where polio cases are still occurring, India happens to be the largest country. India cannot become polio free unless Uttar Pradesh and Bihar become polio free. There was a quick decline in polio incidence in some states in India, while other states reported decline slowly, but, Uttar Pradesh and Bihar have never been polio free since the polio eradication programme was launched in 1995. Despite increase in number of pulse polio immunization (PPI) rounds since year 2000 and introduction of monovalent polio vaccine type 1 (mOPV1) and type 3 (mOPV3) in Uttar Pradesh in 2005, there has been no respite in polio incidence in Uttar Pradesh and Bihar. Lately, majority of polio cases being reported from other states are occurring in migrant population from Uttar Pradesh and Bihar, and also molecular study shows that polioviruses being detected in other states have origin in Uttar Pradesh or Bihar. Thus, there is an urgent need to develop a new vaccine or strategy specifically for Uttar Pradesh and Bihar.     

Role of genetic factors in polio eradication: new challenge for policy makers

In 1988 the World Health Assembly passed resolution WHA 41.28, for global eradication of poliomyelitis by the year 2000 by providing immunization exclusively with oral polio vaccine (OPV). India happens to be the largest country in the world, where polio cases are occurring in large numbers. Despite increase in number of pulse polio immunization (PPI) rounds and introduction of monovalent oral polio vaccines mOPV1 and mOPV3, polio has not been eradicated from India. Global polio eradication cannot be achieved unless polio is eradicated from India because of the risk of exportation of wild poliovirus to other countries. India cannot become polio free unless Uttar Pradesh and Bihar become polio free. Because of genetic and some other factors, OPV cannot eradicate polio from Bihar and Uttar Pradesh. The present scenario strongly suggests that due to some host factors in recipients OPV cannot eradicate polio. Rather than extending the deadline for polio eradication again and again, it is time to prepare strategy for final push to polio.     

Progress toward poliomyelitis eradication--India, 2002

Since the World Health Assembly resolved in May 1988 to eradicate poliomyelitis, the estimated global incidence of polio has decreased >99%, and three World Health Organization (WHO) regions (Americas, Western Pacific, and European) have been certified as polio-free. In 1995, India began accelerating polio eradication activities. By 2001, poliovirus circulation had been limited largely to the two northern states of Uttar Pradesh (UP) and Bihar, with 268 cases reported nationwide. However, in 2002, a major regional resurgence of polio occurred. As of January 25, 2003, a total of 1,556 cases were detected nationwide, of which 1,337 (86%) were in UP and Bihar. This report summarizes the status of polio eradication activities in India during 2002, analyzes the factors contributing to the resurgence, and describes the actions being taken to reduce poliovirus transmission.     

Progress toward poliomyelitis eradication--Afghanistan and Pakistan, January 2004-February 2005

Although poliomyelitis remained endemic in only six countries at the end of 2003, a resurgence of polio occurred in 2004, originating in Nigeria and resulting in the export of wild poliovirus (WPV) into the polio-free countries of western and central Africa. However, progress toward interrupting WPV transmission continued during 2004 in Afghanistan, India, and Pakistan, the only remaining countries in Asia where polio is endemic. This report summarizes progress toward polio eradication in Afghanistan and Pakistan during January 2004-February 2005 and indicates that, with continued support from national and local leaders, interruption of poliovirus transmission in both countries is feasible by the end of 2005.     

Outbreak of polio in adults--Namibia, 2006

After 10 years with no detected wild poliovirus (WPV) transmission in Namibia, an outbreak of poliomyelitis cases occurred in 2006. The outbreak was traced to importation from neighboring Angola of WPV type 1 (WPV1) that originated in India. As of October 2, 2006, a total of 19 cases of polio, with paralysis onset between early May and June 26, had been confirmed by isolation of WPV1 from stool specimens, primarily from young adult males; six of the patients died. This report describes outbreak investigation and response activities and provides an update on routine and supplemental immunization activities (SIAs) and acute flaccid paralysis (AFP) surveillance in Namibia.     

脊髓灰质炎疫苗应用现状及免疫策略进展

1988年,全球消灭脊髓灰质炎（脊灰）倡议行动启动以来,取得了重大进展。2012年,全球报告脊灰223例,较2011年减少〉60%,本土脊灰流行国家减少为尼日利亚、巴基斯坦和阿富汗,脊灰野病毒（Wild Poliovirus,WPV）病例数下降到历史最低水平。但WPV传播仍未被阻断,无脊灰国家/地区仍面临输入WPV的风险。同时,有些国家正面临使用口服脊灰减毒活疫苗（Oral Poliomyelitis Attenuated Live Vaccine,OPV）所致疫苗衍生脊灰病毒的风险。目前,不同国家/地区评估各自的脊灰发病风险,依据OPV、脊灰病毒灭活疫苗（Inactivated Poliovirus Vaccine,IPV）的风险和收益,不同国家/地区采用不同的免疫策略：仅使用IPV、序贯使用IPV/OPV和仅使用OPV。2013年,世界卫生组织《全球消灭脊灰终结战略计划》中提出,2014年全球阻断WPV传播,2015年所有国家应至少使用1剂IPV,停用OPV中的Ⅱ型组分;2018年完成消灭WPV证实后,停用OPV。现对OPV和IPV的应用现状以及免疫策略进行简述。     

OPV cannot eradicate polio from India: do we need any further evidence?

Polio eradication programme was launched in India in 1995, and polio eradication was expected to occur by 2000. Remarkable decline in polio incidence occurred, but, polio was not eradicated. Majority of polio cases are occurring in two states viz., Uttar Pradesh and Bihar. It is also being observed that majority of polio cases had received many doses of polio vaccine. In 2005 monovalent OPV1 (mOPV1) and monovalent OPV3 (mOPV3) were also introduced in Uttar Pradesh and Bihar, but, number of polio cases increased 10-fold in 2006. In 2007 number of vaccination rounds were increased to one round every month, but in 2007 number of polio cases increased further. In 2005 there were 66 polio cases whereas in 2006 and 2007 number of polio cases increased to 676 and 863, respectively. Some genetic factors in children from Uttar Pradesh and Bihar appear to be responsible for poor antibody generation by OPV. Some mutations in polio viruses may be responsible for development of resistance to antibodies generated by OPV and a reason for the recent steep rise in polio incidence since 2006. Because of these two factors, OPV cannot eradicate polio from India.     

Progress toward poliomyelitis eradication--poliomyelitis outbreak in Sudan, 2004

After the World Health Assembly of the World Health Organization (WHO) resolved in 1988 to eradicate poliomyelitis globally, the number of countries in which polio is endemic declined from 125 to six by 2003. However, in 2004, polio cases caused by wild poliovirus (WPV) originating from northern Nigeria were reported in 11 countries--Benin, Botswana, Cameroon, Guinea, Mali, Saudi Arabia, Burkina Faso, Central African Republic, Chad, Cote d'Ivoire, and Sudan--reestablishing transmission in the latter five countries. Sudan, a member state of the WHO Eastern Mediterranean Region, initiated poliomyelitis eradication activities in the northern area of the country in 1994 and in the south in 1998. Since 1998, Sudan has made substantial progress in implementing polio eradication strategies, with no WPV reported from May 2001 through April 2004. However, in May 2004, a WPV case was detected in West Darfur, and a polio outbreak is currently affecting 17 of the country's 26 states. This report describes the outbreak and response and provides an update on acute flaccid paralysis (AFP) surveillance and supplementary immunization activities (SIAs) in Sudan. The outbreak underscores the importance of continued SIAs in polio-free countries with low routine vaccination coverage, even in areas with moderate to low population density, as well as the need to ensure uniformly high-quality AFP surveillance.     

Progress toward poliomyelitis eradication--India, January 2004-May 2005

Since 1988, the global incidence of polio has decreased by more than 99%, and three World Health Organization (WHO) regions (Americas, Western Pacific, and European) have been certified as polio-free . India, the largest of the six countries where polio remains endemic, experienced a large polio outbreak (1,600 cases) in 2002. Since then, the Government of India (GOI) has accelerated its polio eradication activities by increasing the number and quality of supplementary immunization activities (SIAs), which reduced the number of reported cases to 225 in 2003, 134 in 2004, and 18 in 2005 (as of June 18). During 2004 and early 2005, taking advantage of the geographic restriction of wild poliovirus (WPV) circulation, GOI and its partners launched several immunization and surveillance strategies to maximize the probability of eliminating poliovirus transmission in India. With continued high-quality interventions, interruption of WPV transmission in India by the end of 2005 appears feasible. This report summarizes progress toward polio elimination during January 2004-May 2005 toward that end.     

Progress toward global eradication of poliomyelitis, 2001

From the initiation of the global poliomyelitis eradication initiative in 1988 through 2001, the number of countries where polio is endemic decreased from 125 to 10, and the number of reported polio cases decreased by >99% from an estimated 350,000 to <1,000. Wild type 2 poliovirus has not been detected worldwide since October 1999. The American and Western Pacific Regions of the World Health Organization (WHO) have been certified free of indigenous wild poliovirus. Current challenges to global polio eradication efforts include ongoing intense transmission in northern India, continued importations of wild poliovirus into polio-free areas, and the detection of circulating vaccine-derived poliovirus (cVDPV). This report summarizes global progress in polio eradication during 2001 and the current status of the initiative.     

Resurgence of wild poliovirus type 1 transmission and consequences of importation--21 countries, 2002-2005

After the 1988 World Health Assembly resolution to eradicate poliomyelitis globally, the number of polio-endemic countries decreased from 125 in 1988 to six (Afghanistan, Egypt, India, Niger, Nigeria, and Pakistan) in 2003. However, during 2002-2005, a total of 21 previously polio-free countries were affected by importations of wild poliovirus (WPV) type 1 from the six remaining countries (primarily Nigeria) where WPV was endemic; four countries (Indonesia, Somalia, Sudan, and Yemen) had outbreaks of >100 polio cases. By the end of 2005, WPV transmission in all 21 countries except Somalia had been interrupted or substantially curtailed. This report summarizes WPV importations into polio-free countries during 2002-2005 and the status of WPV transmission in these countries as of January 24, 2006, and describes actions that polio-free countries can take to improve importation preparedness.     

Strategies for eradication of poliomyelitis--the Indian experience.

Substantial progress has been made towards achieving global eradication of poliomyelitis by the end of the year 2000; the goal set by the World Health Assembly in May 1988. The basic strategies to eradicate polio are: attaining high routine coverage with at least three doses of OPV; conducting national immunization days (NIDs) in polio endemic countries; establishing a sensitive system of acute flaccid paralysis (AFP) surveillance to track wild poliovirus circulation; and conducting "mopping-up" immunization when polio is reduced to focal transmission. By the end of 2000. India was in the midst of the sixth National Immunization Days (NIDs). Surveillance system for Acute Flaccid Paralysis (AFP) continued to achieve the recommended non-polio AFP rate of at least 1 per 100,000 population < 15 years per year (1.88 for week 51 ending 23rd December 2000), the adequate stool specimen collection rate was 83% that met the target of > 80%. Some States in the south and west have started to implement mopping-up immunization campaigns as the end-stage strategy to eliminate the last remaining foci of transmission. While most of India appears to be well placed to eradicate polio by the end of 2000 or shortly thereafter, concerns remain about low coverage in parts of the densely populated northern States of Uttar Pradesh and Bihar where high intensity transmission persists. The Government of India has embarked upon an intensified strategy that relies on extra rounds of NIDs; house-to-house immunization to reach previously missed children; and aggressive mopping-up campaigns including pre-emptive mopping-up in the known reservoirs in Uttar Pradesh and Bihar. Extensive microplanning and supervision of the supplementary immunization activities is critical to achieve the target of polio eradication.