Western Pacific Region. Maintaining polio-free status

Western Pacific Region Maintaining polio-free status Regional strategic plan 2008-2012

Foreword When the Western Pacific Region was certified polio-free on 29 October 2000, we all realized that this achievement opened a new chapter in the book of human endeavors for health. Not only were we saving countless children from polio, but we also were setting an example for other regions. We proved that no matter how daunting a goal may be, it can be achieved if we share the same vision, commit ourselves to achieving it, and work together in a spirit of solidarity. Two years later, in 2002, the WHO European Region was likewise certified polio-free and interruption of global wild poliovirus transmission was expected in the near future. The number of countries in which polio was endemic had declined from 125 in 1988 to 6 by the end of 2003. However, global progress was threatened by a resurgence of polio in Africa, which resulted in a regional spread of wild poliovirus type 1 from Nigeria into 21 previously polio-free countries, followed by an intercontinental spread to the Middle East and South-East Asia (Indonesia). Likewise, continuing endemic polio transmission in northern India resulted in an intercontinental spread of wild poliovirus, also into the proximity of our Region (Nepal). Importations of wild poliovirus into the Western Pacific Region were reported in Singapore (2006, from Nigeria) and Australia (2007, from Pakistan). Fortunately, these episodes did not result in subsequent cases or polio outbreaks because of the preparedness of Member States. At the earliest, we are expecting interruption of wild poliovirus transmission globally by the end of 2009, and global certification earliest by the end of 2012. The challenge to the Western Pacific Region and its Member States is to sustain acute flaccid paralysis surveillance and polio immunization at the levels needed for the early detection of, and response to, wild poliovirus importations and emergence of circulating vaccine-derived poliovirus. To support Member States in this task, we have, in close consultation with all key partners, developed the Regional Strategic Plan for the Maintenance of Polio-free Status 2008-2012 to spell out technical requirements, to clarify roles and responsibilities for certification bodies in the period between regional and global certification, and to be used for advocacy purposes and fund-raising. By continuing our efforts to keep the Western Pacific polio-free, we are significantly supporting the Global Polio Eradication Initiative to focus all its energy on the remaining areas of transmission and setting encouraging examples that even seemingly insurmountable problems can be solved as long as the highest levels of determination and political commitment are put into place. i

Executive summary With the extended time-frame for global wild poliovirus eradication and subsequent certification, Member States, National Immunization Programmes, WHO and other polio partners have to make longer-term preparations to have the necessary, human, technical and financial, resources available to maintain high quality immunization and surveillance systems. Subsequently, the WHO Western Pacific Regional Office developed the Regional Strategic Plan for the Maintenance of Polio-free Status 2008-2012. Besides describing current performance levels, the plan provides recommendations (pages 18-27) as well as estimates for external funding requirements (Annex 6) for the following key areas of action: ensuring continuous political commitment and support; maintaining high-level immunity against polio; sustaining high-quality surveillance for polio; preparedness for controlling wild poliovirus importations and circulating vaccine derived poliovirus; meeting requirements for poliovirus laboratory containment; maintaining the certification process; preparing for post-eradication; and ensuring appropriate financial and human resources. Reported routine immunization coverage against polio has been maintained at levels similar to previous years and at certification time, with the large majority of countries achieving over 70%. However, the reported coverage may overestimate protection as it is known that immunity gaps continue to exist in some areas. This has also been indicated by various vaccine derived poliovirus episodes in the Western Pacific Region. Universal high routine coverage becomes increasingly important as capacities to conduct preventive supplementary immunization activities go down. Although there is variation between the years and areas, most countries maintain adequate levels of acute flaccid paralysis case reporting and regular data analysis at appropriate subnational levels is being conducted to identify and respond to surveillance gaps. Since certification, over 75 000 acute flaccid paralysis cases have been investigated. The overall key quality indicators have remained stable, but there are areas with poorer performance. The regional poliovirus laboratory network remains key to provide timely and accurate virological information. It is currently comprised of one global specialized (Japan), two regional reference (Australia, China), nine national and 31 Chinese provincial poliovirus laboratories. All laboratories participate in annual proficiency tests provided by the Global Polio Laboratory Network and undergo regular external accreditation. All laboratories except the provincial laboratory in Tibet (China) are currently accredited and performing under general WHO standards. ii

Addressing the ongoing risk of wild poliovirus importation into poliomyelitis-free countries is crucial. Most countries have recently conducted risk assessments and have updated or enhanced their preparedness plans; these capacities have to be maintained. With China and Japan having submitted their final quality assessment on Phase 1 wild poliovirus laboratory containment in November 2008, survey activities have been completed in all countries and national inventories established. Planning has to commence for requirements in Phase 2, for which implementation will have to begin one year after detection of wild poliovirus anywhere in the world. The Technical Advisory Group on Immunization and Vaccine Preventable Disease in the Western Pacific Region reviewed the draft strategic plan during its 17th meeting in July 2008 and endorsed its general principles and key areas for action. Afterwards, the draft plan underwent further detailed review by National Immunization Programmes and key partners. Finally, the strategic plan was endorsed by the Regional Commission for the Certification of Poliomyelitis Eradication in the Western Pacific Region during its 14th meeting in December 2008. Maintaining the polio-free status of the Region must continue to receive attention in order to protect the enormous investments already made by each country and area. A resurgence of polio, due to either wild poliovirus or circulating vaccine-derived poliovirus, would result in huge additional resource requirements, as shown in the control of polio outbreaks following importations into polio-free areas, and cause enormous burdens for national health systems, which already have to address many other concerns. iii

List of abbreviations ACPE Advisory Committee on Polio Eradication AFP acute flaccid paralysis ELISA enzyme-linked immunosorbent assay GAP II WHO Global Action Plan for Wild Poliovirus Laboratory Containment, 2nd edition HBAS hospital-based active surveillance HbsAg hepatitis B surface antigen ICC interagency coordinating committee IHR International Health Regulations ITD intratypic differentiation IPV inactivated poliovirus vaccine JRF WHO/UNICEF Joint Reporting Form for Vaccine Preventable Diseases NCC National Certification Committee NID National Immunization Day NIP National Immunization Programme NPEV non-polio enterovirus NRA national regulatory authority NWFP North West Frontier Province OPV oral poliovirus vaccine (trivalent) mopv1 monovalent oral poliovirus vaccine type 1 mopv3 monovalent oral poliovirus vaccine type 3 PPHSN Pacific Public Health Surveillance Network PT proficiency test RCC Regional Commission for the Certification of Poliomyelitis Eradication SIA supplementary immunization activity TAG Technical Advisory Group on the Expanded Programme on Immunization and Poliomyelitis Eradication VAPP vaccine-associated paralytic polio VDPV vaccine-derived poliovirus avdpv ambiguous vaccine-derived poliovirus cvdpv circulating vaccine-derived poliovirus ivdpv vaccine derived poliovirus related to immune deficient person VPD vaccine-preventable disease WHA WHO World Health Assembly XLA X-linked agammaglobulinemia iv

Table of contents Introduction 1 Global polio eradication initiative 2 Maintaining the polio-free status in the Western Pacific Region 4 o Certification process 4 o Immunization coverage 5 o Quality of polio/afp surveillance 7 - Wild poliovirus importations into the WPR since certification 10 Singapore 2006 10 Australia 2007 11 - Vaccine-derived polioviruses 11 o Regional poliovirus laboratory network 12 o Risk assessment for spread of imported wild poliovirus 14 o Wild poliovirus laboratory containment 15 Key areas for action 18 o Ensuring continuous political commitment and support 18 Member States 19 WHO 19 Partners 19 o Maintaining high-level immunity against polio 19 - Routine immunization 19 Member States 20 - Supplementary Immunization 20 Member States 20 WHO 20 o Sustaining high-quality surveillance for polio 21 - AFP surveillance 21 Member States 21 WHO 22 - Polio laboratory network 22 Member States 22 WHO 23 o Preparedness for controlling wild poliovirus importations and cvdpv 23 Member States 23 WHO 24 o Meeting requirements for poliovirus laboratory containment 25 Member States 25 WHO 25 o Maintaining the certification process 25 RCC 25 NCC 26 o Preparing for post-eradication 26 Member States 26 WHO 27 o Ensuring appropriate financial and human resources 27 Member States 28 WHO 28 v

FIGURES Figure 1 - Wild poliovirus infected districts, 12 May 2008-11 Nov 2008 3 Figure 2 - Declaration of certification of polio-free status in Kyoto, Japan 4 Figure 3 - Reported national polio3 coverage 5 Figure 4 - Regional non-polio AFP rate and % of cases with adequate stool samples 1992-2008 8 Figure 5 - Non-polio AFP rate by country in the WPR 2005-2007 9 Figure 6 - Polio laboratory network in the Western Pacific Region 12 Figure 7 - Polio laboratory network performance indicators 2005-2008 14 TABLES Table 1 - Supplementary immunization against polio in the WPR 2001-2008 6 Table 2 - Poliovirus isolation in the WPR 2001-2007 10 ANNEXES Annex 1 - Reported polio3 coverage 2000-2007 Annex 2 - WPR polio vaccine schedules Annex 3 - VDPV in the WPR summary 2001-2007 Annex 4 - Key indicators AFP surveillance and polio laboratory performance Annex 5 - WHA59 Resolution 1 polio Annex 6 - Draft cost estimates 2008-2012 for countries and WPRO vi

Introduction The WHO Western Pacific Region was certified as polio-free on 29 October 2000, more than three years after the onset of the last indigenous wild poliovirus case in Cambodia in March 1997. Almost two years later, on 22 June 2002, the WHO European Region was likewise certified polio-free and interruption of global wild poliovirus transmission was expected in the near future. The number of countries in which polio was endemic declined from 125 in 1988 to six by the end of 2003. However, global progress was threatened by a resurgence of polio in Africa at that time. Discontinuation of supplementary immunization activities (SIAs) in parts of northern Nigeria during the period 2003 2004 and the ongoing failure to reach children in many countries with routine immunization services resulted in regional spread of wild poliovirus type 1 from Nigeria into 21 previously polio-free countries, followed by intercontinental spread to the Middle-East and Asia (Indonesia). Continuing endemic polio transmission in northern India similarly resulted in intercontinental spread of wild poliovirus type 1 to Angola and Lebanon, as well as contiguous spread to Nepal. Importations continued in 2006 and 2007, with polio entering into Bangladesh and Myanmar in the WHO South-East Asia Region and into Singapore (2006, from Nigeria) and Australia (2007, from Pakistan). Fortunately, the wild poliovirus importation episodes into the Western Pacific Region did not result in subsequent cases and polio outbreaks. Despite the encouraging global progress in suppressing wild poliovirus type 1 in all endemic countries, wild poliovirus transmission continues in four endemic countries and several countries with outbreaks following importations. The persistence of wild poliovirus transmission has once again led to a shift in the anticipated timeline towards global certification, with interruption of wild poliovirus transmission globally now expected earliest at the end of 2009, and global certification earliest at the end of 2012. The challenge to the Western Pacific Region and its Member States continues to be to sustain quality acute flaccid paralysis (AFP) surveillance and polio immunization at the levels needed for the early detection of and response to both, wild poliovirus importations and emergence of circulating vaccine-derived poliovirus (cvdpv). In view of this multi-year time-frame for global certification, the Regional Commission for the Certification of Poliomyelitis Eradication in the Western Pacific Region (RCC) during its 13th meeting in December 2007 suggested to WHO to develop of a Regional Strategic Plan for the Maintenance of Polio-free Status to spell out technical requirements, to clarify roles and responsibilities for certification bodies in the period between regional and global certification, and to be used for advocacy purposes and fund-raising. 1

Global Polio Eradication Initiative In 1988, the WHO World Health Assembly (WHA) resolved to eradicate poliomyelitis. Subsequently, the Global Polio Eradication Initiative reduced the worldwide incidence of polio associated with wild polioviruses from an estimated 350 000 cases in 1988 to 1997 cases in 2006. It also reduced the number of countries that have never succeeded in interrupting wild poliovirus transmission from more than 125 to four Afghanistan, India, Nigeria and Pakistan (Figure 1). Circulation of type-2 wild poliovirus was last observed in October 1999. In February 2007, during a stakeholders meeting convened by WHO, a decision was made to accelerate eradication efforts during 2007 2008 and to set milestones to monitor progress. Programmatic strategies implemented in 2007 included: expanding the use of type-1 monovalent oral poliovirus vaccine (mopv1) to eliminate transmission of type-1 wild poliovirus (before type 3 wild poliovirus) and targeting the use of type 3 monovalent OPV (mopv3) in selected areas. In 2007, substantial progress was made towards limiting the geographical extent and number of cases of type-1 wild poliovirus transmission in India; these gains were the result of intensive supplementary immunization activities (SIAs) and an increased use of mopv1 in affected areas. However, significant transmission of type 3 wild poliovirus occurred in the states of Bihar and Uttar Pradesh owing to the focus on eliminating type-1 wild poliovirus, the limited supply of mopv3 in India, the restricted use of trivalent OPV during SIAs in 2007 and the underlying insufficiency of routine immunization coverage. In 2008, 18 districts are infected with type 1 wild poliovirus, compared to 40 districts for the same period in 2007 (a 55% reduction). Interrupting type 1 poliovirus transmission in India as soon as possible remains a primary strategic objective of the Global Polio Eradication Initiative. The key to success is sustaining the political momentum that has brought India so close to eradicating type 1 poliovirus. In 2007, the incidence of type-1 wild poliovirus cases and the number of affected districts decreased substantially in Nigeria. However, this decline was sustained; in 2008, the type-1 wild poliovirus case count was higher than during the equivalent period in 2007. The proportion of children who were missed during SIAs and routine immunization remains critically high (>10%) in certain states in Nigeria. Major efforts to strengthen routine immunization services and the quality of SIA implementation continue. In 2008, 87 cases were reported in Pakistan and 22 cases in Afghanistan. The spread of poliovirus was due to a combination of factors, including: deteriorating security in known endemic areas (resulting in increased population movements); increased susceptibility of populations in areas free of the disease due to fewer SIAs during the last 12 months; suboptimal vaccination coverage in key areas; and an immunity gap for type 3 virus in key districts of North West Frontier Province due to the suboptimal vaccination coverage and compounded by the emphasis given to the use of mopv1 in these same districts. 2

Figure 1: Wild poliovirus infected districts, 12 May 2008 11 November 2008 (WHO Headquarters dataset as of 11 November 2008) district infected with wild poliovirus type 1 district infected with wild poliovirus type 3 district infected with wild poliovirus type 1 and 3 Recognizing the short- and long-term risks to polio eradication, the World Health Assembly adopted Resolution WHA61.1 in May 2008, urging all remaining polio-affected Member States to ensure that every child is vaccinated during every SIA, and requesting the WHO Director-General to set, if and when appropriate, a date for the eventual cessation of OPV use in routine immunization programmes. The technical feasibility of eradicating polio has been demonstrated repeatedly by the ability to interrupt transmission of wild poliovirus in areas with comprised security and limited health infrastructure, such as Somalia. In 2007, the feasibility was highlighted again with the substantial progress made towards interrupting type-1 wild poliovirus transmission in India. Further information about the global polio situation is available on the following website: http://www.polioeradication.org. 3

Maintaining the polio-free status in the Western Pacific Region Certification process On 29 October 2000, the Regional Commission for the Certification of Poliomyelitis (RCC) concluded that the transmission of indigenous wild poliovirus had been interrupted in all countries and areas of the Western Pacific Region. As such, the Region was certified as poliofree (Figure 2). Figure 2: Declaration of certification of polio-free status in Kyoto, Japan The RCC required national and subregional certification committees to continue to function until global certification is achieved in order to fulfil its obligations to the Global Certification Commission. Prior to regional certification, following the 1996 Plan of Action Certification of the Eradication of Poliomyelitis in the Western Pacific Region, all countries had been required to establish National Certification Committees (NCCs) and develop national certification plans. A subregional committee was appointed for the Pacific island countries and areas due to their unique epidemiological situation. 4

Since regional certification, the RCC has continued to meet on an annual basis to review written progress reports from all countries and areas. The reports place particular emphasis on ongoing surveillance, maintenance of high immunization rates, wild poliovirus importation preparedness, laboratory containment of wild poliovirus infectious and potentially infectious materials, and evidence of continued political commitment on the part of governments. In addition to these sections, the reports contain a brief executive summary and references to recommendations made by the RCC during its previous meeting, where applicable. Guidelines are prepared each year to facilitate the completion of these reports. NCCs are requested not only to review and endorse the report, but also to contribute to a summary of conclusions and recommendations. Progress reports have to be presented to the RCC with a cover letter signed by the NCC chairperson or designated representative. After their meeting, the RCC sends individualized letters, signed by the chairperson, to all NCC chairpersons. The letters put forth their main general findings and conclusions and all country-specific recommendations. Active NCCs remain in place in almost all countries. In countries with small populations and limited technical expertise, some NCCs also function as expert panels to review and classify AFP cases. Immunization coverage Reported routine immunization coverage against polio has been maintained at levels similar to previous years and at certification time; with the large majority of countries achieving over 70%. The latest reported data are reflected in Figure 3 and details per country (2000 2007) included in Annex 1 (source: 'Joint Reporting Form on Vaccine Preventable Diseases' JRF) Figure 3: Reported national polio3 coverage Source: Joint Reporting Form (JRF) on Vaccine Preventable Diseases, 2007 (JRF, 2006 for Guam; JRF, 2005 for Brunei Darussalam) 5

However, the reported coverage may overestimate protection as it is known that immunity gaps continue to exist in some areas, particularly in the Lao People's Democratic Republic, Papua New Guinea, some Pacific island countries and areas, and high-risk communities and populations in China and the Philippines. This has also been indicated by various vaccinederived poliovirus (VDPV) episodes in the Region (details in the surveillance section). National immunization schedules vary greatly. Currently, 12 countries and areas are using inactivated poliovirus vaccine (IPV) and 24 are using OPV. Japan and Macao (China) are planning to shift from OPV to IPV in the near future. With the Region free of wild poliovirus for over 10 years, the risk of vaccine associated paralytic polio (VAPP) and VDPV is increasingly influencing vaccination policy changes. Two countries still give an OPV birth dose, and 20 out of 36 provide polio vaccine booster doses (details in Annex 2). Supplementary immunization with OPV has been gradually reduced since certification, mainly due to a lack of funding. It is usually conducted in high-risk areas (HR). See Table 1. Table 1: Supplementary immunization against polio in the Region, 2001 2008 Year Country Type # rounds Target # 2001 Cambodia SIA 2 HR 103 000 China SIA 2 HR 28 million Lao People s Democratic Republic SIA 2 HR 200 000 Viet Nam SIA 2 HR 550 000 2002 China SIA 2 HR 28 million Philippines NID 2 cvdpv 12 million Viet Nam SIA 2 HR 315 000 2003 Cambodia SIA 2 HR 159 000 China SIA 2 HR Lao People s Democratic Republic SIA 2 HR 280 000 Papua New Guinea SIA 1 49 000 Viet Nam SIA 2 HR 150 000 2004 China SIA 2 HR Papua New Guinea SIA 1 18 000 Viet Nam SIA 2 HR 850 000 2005 Cambodia SIA 1 HR 158 000 China SIA 2 HR 13 million Philippines SIA 2 HR 600 000 Viet Nam SIA 2 HR 2.6 million 2006 Cambodia SIA 2 cvdpv 815 000 China SIA 2 HR 23 million Viet Nam SIA 2 HR 3 million 2007 China SIA 2 HR 25 million 2008 China SIA 2 HR Lao People s Democratic Republic SIA 2 HR 200 000 6

The polio outbreak in Indonesia in 2005 triggered SIAs throughout the Region, particularly in the Philippines and Viet Nam. Activities conducted from 2001 to 2007 are listed in Table 3, with planned SIAs in 2008 indicated in italics. It should be noted that in addition to the activities listed here, China conducted various response SIAs following detection of VDPV. Otherwise, strong priority is placed on strengthening routine immunization systems but progress often remains slow. Quality of polio and AFP surveillance In the majority of countries in the Western Pacific Region, polio surveillance is based on reporting and investigation of AFP cases; public health staff at various levels are supposed to conduct active searches for cases on a regular basis. In several countries and areas, such as Australia, Hong Kong (China), New Zealand, and Singapore, all practitioners or key physicians, mainly paediatricians and other hospital clinicians, are supposed to notify AFP cases involving children less than 15 years of age to designated surveillance units, which then coordinate a complete investigation. The Republic of Korea has conducted a special active AFP study in the greater Seoul area from 2001 to 2007 and environmental surveillance projects, supplemented by case reporting from 105 sentinel hospitals. Supplementary nationwide enterovirus surveillance has been recently strengthened with more active participation of sentinel hospitals. In Japan, the virological surveillance of enteroviruses including polioviruses has been the key element of infectious agents surveillance ongoing since 1970. In the 20 Pacific island countries and areas, which, for certification purposes, were considered as an epidemiological block, a hospital-based active surveillance (HBAS) network structure is in place. It comprises 58 hospitals distributed throughout the 20 countries and areas, and involves 20 national coordinators, 58 hospital coordinators, and over 200 key paediatric clinicians. The reporting mechanism in most countries continues to require a copy of the completed monthly active surveillance form to be sent from the hospital coordinator to the national coordinator and copied to WHO at least every three months. Surveillance data including laboratory data are regularly submitted to WHO, reviewed for data quality and system performance levels and published in the weekly polio surveillance bulletin. When new quality indicators are recommended by global polio advisory bodies, they are communicated to national immunization programmes. Compliance is usually satisfactory. Immediately after certification, the Technical Advisory Group on the Expanded Programme on Immunization and Poliomyelitis Eradication in the Western Pacific Region (TAG) concluded that any future modification of surveillance standards could only take place under circumstances of consistently high quality performance of AFP and laboratory surveillance, together with supportive scientific evidence. Reducing the requirement of AFP surveillance to a single stool specimen from each AFP case was discussed in terms of reducing stool sample collection and shipment costs and laboratory workload. 7

However, in view of a risk of lower surveillance sensitivity, especially if laboratory performance is variable, and giving the wrong message to surveillance staff when the Region remains at exposure to importation, countries decided to continue with the practice of two adequate stool specimens. Depending on local circumstances, countries were given the option to cease 60-day follow-up for AFP cases when two adequate stools tested negative for poliovirus. However, few countries have opted for this approach. In Australia, follow-up is not required by the Polio Expert Committee (the national expert panel) if a case can be classified as non-polio AFP on the information available. Meanwhile, all other surveillance standards should be maintained at certification levels as recommended by the RCC or other global polio advisory bodies. Since certification, more than 75 000 AFP cases have been investigated and the overall key quality indicators have remained stable; with a regional non-polio AFP rate consistently above 1 per 100 000 children under 15 years of age and the adequate stool sample collection rate almost reaching 90% (Figure 4). Figure 4: Regional non-polio AFP rate and percentage of cases with adequate stool samples, 1992 2008 (dataset as of 17 November 2008, annualized for 2008) Non-polio AFP rate 2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 non-polio AFP rate 0.03 0.35 0.75 1.21 1.17 1.35 1.43 1.40 1.49 1.39 1.47 1.39 1.61 1.39 1.83 1.62 1.15 % AFP cases with adequate specimens 20% 27% 45% 71% 79% 83% 86% 86% 90% 88% 88% 88% 88% 88% 89% 90% 85% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% % AFP cases with adequate specimens Although there has been variation between the years, most countries maintain adequate levels of AFP case reporting. The RCC requests regular data analysis at appropriate subnational levels to identify and respond to surveillance gaps. 8

Countries that did not achieve a minimum rate of 1 per 100 000 in children under 15 years in 2007 were Australia (0.68) the Republic of Korea (0.3), the Lao People s Democratic Republic (0.7; with continued concerns about low performance) and New Zealand (0.5). Notable performance improvements occurred in Papua New Guinea where reporting reached minimum requirements after several years of struggling. See Figure 5. Figure 5: Non-polio AFP rate by country in the Western Pacific Region, 2005 2007 (dataset as of 20 May 2008) 4.00 3.50 3.00 2005 2006 2007 Non-polio AFP rate 2.50 2.00 1.50 1.00 0.50 0.00 Australia Brunei Darussalam Cambodia China Hong Kong, China Korea, Republic of Lao PDR Macao, China Malaysia Mongolia New Zealand PIC Papua New Guinea Philippines Singapore Vietnam Further details about AFP surveillance performance are available on the following website: http://www.wpro.who.int/sites/epi/documents/polioweeklybulletin.htm Expert panels that review and classify AFP cases as required are in place in almost all countries. Meetings are held either face-to-face or as teleconferences, often synchronized with the reporting dates of WHO Headquarters for the quarterly publication of AFP surveillance data in the WHO Weekly Epidemiological Record. In some countries like Malaysia and the Philippines, expert panels review all cases in order to ensure that clinical investigation and management results concur with a final diagnosis other than polio and supplement lower adequate stool sample collection rates. In several countries, AFP surveillance is being supplemented by stool surveys in healthy children and stool sample collection from AFP case contacts. Others identify polioviruses through enterovirus surveillance systems. Following the recommendations of the Global Polio Eradication Initiative, surveillance was expanded after certification to also search for VDPV and required laboratory testing methods for intratypic differentiation (ITD) were introduced. Since 2003, poliovirus isolates from all sources have been reported to WHO and standard tests have been applied to all poliovirus isolates with discordant ITD results. 9

Identification of poliovirus isolates from AFP cases and other sources (mainly healthy children and contacts of AFP cases) appears to be influenced by several factors, including reduction of supplementary OPV immunization, level of general enterovirus testing for clinical samples and changes in immunization schedule (shift from OPV to IPV). Table 2: Poliovirus isolation in the Western Pacific Region, 2001 2007 Year # AFP cases # AFP cases with stool samples # AFP cases with PV isolates # poliovirus isolates # wild poliovirus # isolates with discordant ITD # VDPV AFP cases non- AFP* AFP cases non- AFP AFP cases 2001 6530 6405 469 576 0 3 2002 6835 6691 501 612 0 58 2003 6397 6252 365 452 90 0 38 5 0 1 2004 6521 6404 391 445 217 0 39 24 4 7 2005 6680 6594 348 405 268 0 32 13 3 3 2006 7011 6909 310 369 176 1** 20 15 2 8 2007 6237 6214 241 323 146 1*** 5^ 2^ 4 0 * reporting requirement to WHO Western Pacific Regional Office since 2003 ** importation into Singapore; paralysis in Nigeria *** Importation into Australia; paralysis in Pakistan ^ due to ELISA reagent shortage sequencing performed as 2nd ITD PV poliovirus non- AFP Wild poliovirus importations into the Western Pacific Region since certification Singapore 2006 On 19 May 2006, the national polio laboratory in Singapore reported isolation of a type 1 wild poliovirus from a stool sample of a female child aged 2 years and 5 months with AFP. The child had developed paralysis in her home in Dutse, Jigawa State, northern Nigeria on 21 April 2006, before travelling to Singapore with her family to seek medical care. The Government of Singapore rapidly took all the necessary steps to minimize and avert a threat to national public health. The existing sensitive AFP surveillance system allowed for the rapid detection, investigation and response to this case and ensured that any additional cases would have been rapidly identified. Routine immunization coverage in Singapore is high at over 90%. The necessity of conducting supplementary immunization activities in response to this case was voided as the risk of secondary spread of virus and subsequent consequences was assessed as low, together with an excellent sanitation infrastructure in Singapore. 10

Supported by WHO, the Ministry of Health of Singapore responded to the polio case immediately by launching a thorough epidemiological investigation and enhancing surveillance for AFP, including the distribution of a public health alert to all private and public sector paediatricians, neurologists and internal medicine specialists in Singapore. Children with whom the index case had come into direct contact, including two who had returned home to Indonesia and one to the Russian Federation, were traced and stool specimens collected. No additional virus-positive cases were found in Singapore, and no poliovirus was isolated in the tested contacts. Australia 2007 On 13 July 2007, the regional polio reference laboratory in Melbourne, Australia, reported isolation of a type 1 wild poliovirus, from a stool sample of a 22-year-old Pakistani man who had returned to Australia on 1 July to continue his studies. Genetic sequencing of the poliovirus isolated confirmed that it was related to virus in North West Frontier Province (NWFP), one of the last remaining polio-infected areas in Pakistan. The risk of onward spread of the poliovirus was considered low due to a number of factors, particularly Australia's strong routine immunization system and excellent sanitation infrastructure. The Government of Australia still undertook a number of additional steps in response to this importation, including enhancing disease surveillance and distributing a public health alert to public health institutions across the country. No further wild polioviruses were found. This was one of the first events reported under the new International Health Regulations (IHR 2005) which came into force on 15 June 2007. Vaccine-derived polioviruses Since certification, three polio outbreaks have occurred due to cvdpv: (1) in 2001 in the Philippines, involving three AFP cases and one positive contact; (2) in 2004 in China, involving two AFP cases and four positive contacts; and (3) from November 2005 to January 2006 in Cambodia, with two AFP cases and one AFP case without VDPV but epidemiologically linked. The immunization response in the Philippines was two rounds of National Immunization Days (NIDs), targeting all children under five years of age and 40% of the target children approached house to house. In China, province-wide SIAs were conducted targeting all children younger than seven years; the two prefectures surrounding the VDPV cases organized three rounds while the remaining two provinces held two rounds. In Cambodia, two rounds of SIAs targeting 200 000 children (approximately 40% of total population) were conducted. In all three episodes, no further VDPVs were found. Fast evolving type 2 and 3 ivdpvs were detected in a child with X-linked agammaglobulinemia (XLA) and AFP in China in 2005, which continued shedding until the child died in 2006. 11

Twenty-four ambiguous VDPVs (avdpvs) have been reported in the Western Pacific Region. Half were identified proactively through AFP surveillance since 2003, while the other half were identified through retrospective laboratory testing after the new ITD standard test requirements had been introduced. Among these avdpv episodes, in four instances, VDPVs were also isolated from healthy contacts, indicating limited transmission (China, 2000, 2006 and 2007; Lao People s Democratic Republic, November 2004-February 2005). However, as in each event not more than one AFP case was identified, the current definition of cvdpv was not applicable. Further details on VDPV identification in the Western Pacific Region can be found in Annex 3. Regional poliovirus laboratory network The polio laboratory network in the Western Pacific Region is comprised of one global specialized (Japan), two regional reference (Australia, China), nine national and 31 Chinese provincial poliovirus laboratories (see Figure 6). Figure 6: Polio laboratory network in the Western Pacific Region, 2008 PHI Global Specialized Lab (1) CCDC Regional Reference Lab (2) KCDC NIID National Lab doing ITD (3) National Lab w/o ITD (6) NIHE GVU RITM China Provincial Lab (31) Pasteur I. IMR SGH IMR(to VIDRL) VIDRL IESR All laboratories participate in annual proficiency tests (PT) provided by the Global Polio Laboratory Network and undergo regular external accreditation. All laboratories except the provincial laboratory in Tibet (China) are currently accredited and performing under general WHO standards. 12

Countries and areas without their own poliovirus laboratories have access to an accredited laboratory within the regional network. Brunei Darussalam, Papua New Guinea and the Pacific island countries and areas submit their samples to the Regional Reference Laboratory in Australia; Macao (China) to the laboratory in Hong Kong (China) and the Lao People s Democratic Republic and Cambodia to the Global Specialized Laboratory in Japan. Three national-level laboratories (Hong Kong [China], New Zealand, Singapore) are also accredited for ITD. Due to the continued global shortage of enzyme-linked immunosorbent assay (ELISA) reagents, ITD is performed by PCR/PCR-RFLP methods and sequencing of the VP1 genomic region; sequencing capacity has recently been established at the national laboratory in Singapore. Other ITD performing laboratories had such capacity already in place. Poliovirus isolation and typing results in 2007 were available within 28 days of receipt for 96% of samples (95% in 2008; with all national-level and provincial laboratories achieving the target). The non-polio enterovirus (NPEV) isolation rate was 9% (same in 2008), slightly below target at similar levels as in previous years. Regular analysis is required at country levels if minimum rates may indicate problems during sample storage and transportation (reverse cold chain) and/or laboratory testing. Availability of ITD results within 14 days of receipt was 58% (76% in 2008) and 52% within 60 days of paralysis onset (37% in 2008); these decreased performance indicators were mainly due to continued global shortage of ELISA ITD reagents and new, stricter biosafety requirements in China, affecting timely transportation of specimens and isolates. See Figure 7 for polio laboratory network performance indicators (2005 2008). The new checklists emphasizing the timely reporting of cell sensitivity testing and management, supervision and biosafety were introduced to the global polio laboratory network in January 2008. It is also planned to introduce the new test algorithm for poliovirus isolation and characterization for the Western Pacific Region polio laboratory network as recommended by the Global Polio Laboratory Network Meeting in June 2006 and by the 17 th TAG meeting in July 2008, while national laboratories are still encouraged to perform neutralization test (NT) for polioviruses. Implementing the new algorithm is expected to reduce the laboratory reporting time for poliovirus isolation and ITD from 42 days to 21 days. 13

100% 80% Figure 7: Polio laboratory network performance indicators, 2005 2008 (dataset as of 17 November 2008 97% 96% 96% 95% 83% 76% 88% 79% 99% 94% 73% 2005 2006 2007 2008 88% 86% 60% 58% 55% 52% 60% 63% 40% 40% 37% 20% 10% 10% 9% 9% 0% NPEV isolation rate % NPL results within 28 days ITD within 14 days of receipt ITD within 28 days of receipt ITD within 60 days of onset ITD within 90 days of onset Further details about AFP surveillance performance are available on the following website: http://www.wpro.who.int/sites/epi/documents/polioweeklybulletin.htm Risk assessment for spread of imported wild poliovirus The risk for wild poliovirus importation into Western Pacific Region countries continues, especially when polio outbreaks occur in close geographical proximity and/or in places with frequent population movements (e.g. the 2005 polio outbreak in Indonesia). The risk was further confirmed by recent importations into less expected places (e.g. Australia and Singapore). One of the requirements for regional certification is for countries to have a national preparedness plan in place and consider detection of wild poliovirus as a national public health emergency. Mainly stimulated by the extended polio outbreak in Indonesia in 2005, the WHO Regional Office for the Western Pacific has developed a regional emergency protocol for wild poliovirus importation, which it regularly updates, and has drafted regional guidelines on responding to the detection of wild poliovirus and VDPV. WHO has also supported countries to update their national plans to include detection of and response to VDPVs. Several Member States outside the Pacific have national plans that take into account the standing recommendations made by the Advisory Committee for Polio Eradication (ACPE) in 2004 and the World Health Assembly in 2006 (WHA59.1), as well as new reporting requirements under the IHR (2005). Some countries are in the process of updating their national plans (e.g. Australia, China, Lao People s Democratic Republic). 14

For the Pacific island countries and areas, the WHO Regional Office for the Western Pacific updated in 2005 the generic plan of action for the Response to Importation of Wild Poliovirus in the Pacific Islands Countries, which was endorsed by the Subregional Certification Commission. This plan of action has been distributed to all EpiNet Teams in the Pacific, and is also available on the Pacific Public Health Surveillance Network (PPHSN) website. Adaptation in 2009 is planned by the national programmes of Fiji and Solomon Islands. In times of frequent and long-distance international travel, wild poliovirus importations cannot be prevented. A risk analysis has been performed for all countries to determine the levels of risk if wild poliovirus were introduced. Based on general risk criteria and annual reports to the RCC, the chance of widespread circulation is currently considered as such: Low risk high reported routine coverage 1 and good quality surveillance 2 for polio Australia, Brunei Darussalam, China (majority of provinces), Hong Kong (China), Japan, Macao (China), Malaysia, Mongolia, New Zealand, the Republic of Korea, Singapore, majority of Pacific island countries and areas Medium risk high reported routine coverage and good quality surveillance for polio but pockets of lower coverage in specific communities with limited access to health care services: Cambodia, Philippines (some provinces), Solomon Islands, Vanuatu, Viet Nam Medium to high risk (large) pockets of poorly immunized communities, surveillance gaps at subnational level but low population density Lao People s Democratic Republic (also VDPV 2004 2005), Papua New Guinea High risk high population density, (large) pockets of poorly immunized communities, surveillance gaps at subnational level China in some provinces (also cvdpv 2004), Philippines in some provinces (also cvdpv 2001) Wild poliovirus laboratory containment Maintaining polio-free status includes keeping accurate and updated national inventories of wild poliovirus infectious and potentially infectious materials still retained in laboratories to ensure they are safely stored under biosafety conditions. 1 At 80% 2 Based on key indicators non-polio AFP rate, adequate stool sample rate, supplementary surveillance activities, hygienic conditions, etc. 15

Laboratory containment in the Region commenced in 1998 with the development of a regional plan of action, endorsed by the RCC. This plan was amended in 1999 based on the Global Action Plan and Timetable for Safe Handling and Maximum Laboratory Containment of Wild Polioviruses and Potentially Infectious Materials and the amendments also endorsed by the RCC. During its fourth meeting, the RCC concluded that for certification of polio-free status, all countries must have made substantial progress towards completion of Phase 1 laboratory containment of wild poliovirus infectious and potentially infectious materials. The RCC recommended that all NCCs should place a high priority on containment and requested all countries to develop a national plan of action and appoint a responsible body to oversee the containment process. In September 1999, at its fiftieth session, the Regional Committee for the Western Pacific passed a resolution (WPR/RC50.R2) requesting the Regional Director to work closely with countries to ensure that substantial progress towards Phase 1 laboratory containment of wild poliovirus infectious and potentially infectious material was attained for regional certification. Subsequently, in November 1999, the Regional Director sent the WHO document entitled Regional Guidelines on the Implementation of Phase I of Laboratory Containment of Wild Poliovirus Infectious/Potentially Infectious Materials to all Member States. By October 2000, all countries in the Region had developed a national plan of action and identified a national authority to implement these plans. Nine countries completed the national inventory before the meeting, whereas 21 countries accomplished it in 2001-2002. Due to a large and complex infrastructure of biomedical laboratories, the development of the Global Action Plan for Laboratory Containment of Wild Polioviruses, 2 nd edition (GAP II) in 2003 and VDPV emergence in the Region, four countries China, Japan, the Philippines and the Republic of Korea conducted subsequent survey phases applying GAP II requirements. While the Philippines and the Republic of Korea completed Phase 1 in 2006, China and Japan completed activities within 2008. All countries except China and Japan prepared laboratory containment quality assessment reports, which were subjected to external review by several senior containment experts. After the consolidation of their conclusions on the thoroughness and reliability of the national surveys and inventories, findings were presented and recommendations made at the 11th RCC meeting in December 2005. Since then, the RCC has concluded that 34 countries have successfully completed Phase I laboratory containment (national/subregional survey and inventory). With China and Japan submitting their final quality assessment reports to the 14th RCC meeting in December 2008, completion of Phase 1 laboratory containment for the whole Region is completed. Four countries in the Western Pacific Region are currently holding wild poliovirus infectious and/or potentially infectious materials: Australia, China, Japan and the Republic of Korea. The RCC has reminded all Member States that a major objective of Phase 1 wild poliovirus laboratory containment is to encourage laboratories to eliminate unnecessary wild poliovirus (including VDPV) infectious and potential infectious materials and provide documentation of actions. 16

The RCC endorsed the ACPE recommendation of November 2007 that all polio-free countries and Regions should complete Phase 1 wild poliovirus laboratory containment by the end of 2008. It also highlighted that that implementation of poliovirus containment is independent of global certification and could be required as early as 2010. Future poliovirus laboratory containment requirements will be defined in the 3rd edition of the WHO Global Action Plan, which is currently under preparation. 17

Key areas for action While the Western Pacific Region was certified polio-free over seven years ago, ongoing transmission of wild poliovirus in other parts of the world and emergence of VDPVs within the Region pose a continuing risk to the polio-free status of all countries of the Region. Continued attention must be given to three key areas. The first is maintaining what has been achieved to date, i.e. high levels of routine immunization and surveillance, both AFP and poliovirus surveillance. Secondly, emphasis must be placed on identifying and correcting programmatic deficiencies. This includes specific populations with poor immunization coverage and subnational areas with poor quality surveillance. Thirdly, specific activities are required before global certification and eventual discontinuation of OPV could take place. This includes poliovirus laboratory containment, informed decision-making on introduction of IPV and technical and political consultations on future OPV cessation. The main elements of this strategic plan, particularly cost estimates, are based on the current assumption that global wild poliovirus transmission is expected to be interrupted by the end of 2009; with global certification expected three years after, namely the end of 2012. Another assumption is that the finalization of global certification agreements will result in the synchronous cessation of global routine OPV use. Ensuring continuous political commitment and support Continuing absence of polio from the Region and multiple other health priorities pose a serious risk that political commitment to and support of national efforts to maintain polio-free status gradually decline, including external financial support. Efforts need to focus not only high quality programme implementation, but also advocacy to national governments and all partners to protect the enormous investments in the programme already made by each country and area. A resurgence of polio, whether due to imported wild poliovirus or cvdpv, would be tragic and would cause enormous burdens for national health systems, which already have to address many other concerns. In September 2005, at the fifty-sixth session of the Regional Committee, Member States unanimously adopted the regional goals of measles elimination and hepatitis B control (i.e. reduction of the chronic hepatitis B virus infection rates among children five years of age to less than 2%, measured by seroprevalence of hepatitis B surface antigen/hbsag) by 2012. In that same resolution, Member States were urged to maintain the polio-free status by sustaining high-quality acute flaccid paralysis surveillance and high immunization coverage of polio vaccines. 18