REGIONAL COMMITTEE Fifty-eighth Session Colombo, Sri Lanka 6-10 September 2005
Provisional Agenda item 13 SEA/RC58/9 18 July 2005
POLIO ERADICATION: FINAL STRATEGY The Tenth Meeting of Health Secretaries of countries of the SEA Region, held in Dhaka on 3-4 July 2005, deliberated, among other subjects, on Polio eradication: Final strategy, which is also an Agenda item of the fifty-eighth session of the Regional Committee. The background document (SEA/HSM/Meet.10/5) prepared for the meeting is attached. During its deliberations, the Meeting of Health Secretaries discussed the status of polio eradication in the SEA Region and the final strategies necessary to attain the final goal. Member States recognized the need for regional solidarity and the need to work together to eradicate polio and maintain their polio-free status, given that some Member States were at a more advanced stage than others in their capacity to maintain polio-free status. Member States reaffirmed their commitment to eradicating polio and the final strategies, including verification of eradication and eventual cessation of OPV use in routine immunization. Nonetheless, Member States expressed concern about the potential for importation and the threat that this represented to their polio-free status. They acknowledged the importance of maintaining high immunization coverage levels, improving sanitation, maintaining high AFP surveillance sensitivity and being prepared for outbreak detection and response. The meeting recommended that Member States should make every effort to interrupt the final chains of indigenous and imported wild-type poliovirus transmission. In addition, in order to maintain their polio-free status, countries should ensure that adequate resources are provided for increasing and maintaining high routine OPV3 coverage and highly sensitive AFP surveillance. Finally, Member States should start the process of developing their national long-term routine immunization policy for the post-polio era. The Agenda item is now submitted to the Regional Committee for its consideration.
WORLD HEALTH ORGANIZATION
REGIONAL OFFICE FOR SOUTH-EAST ASIA
Tenth Meeting of Health Secretaries of Countries of SEAR Dhaka, Bangladesh, 3-4 July 2005
SEA/HSM/Meet.10/5 7 June 2005
Polio Eradication: Final Strategy
CONTENTS 1. BACKROUND 2. GLOBAL STATUS OF POLIO ERADICATION 3. STATUS OF POLIO ERADICATION IN THE SOUTH-EAST ASIA REGION 4. STATUS OF THE CERTIF ICATION PROCESS IN THE SOUTH-EAST ASIA REGION 5. STATUS OF LABORATORY CONTAINMENT IN THE SOUTH-EAST ASIA REGION 6. OPV CESSATION - THE FINAL STRATEGY FOR POLIO ERADICATION 7. RISKS ASSOCIATED WITH OPV CESSATION 8. PRIORITIES FOR SEAR 9. ISSUES 9.1 9.2 9.3 9.4 9.5 Interrupting the Final Chains of Wild-type Poliovirus Transmission in India Strengthening Surveillance for Polio Cases and Polioviruses Preparing for the Synchronous Cessation of Oral Poliomyelitis Vaccine Use Ensuring Sufficient Financing Injectable Polio Vaccine (IPV) 1 1 1 2 3 3 4 5 5 5 6 6 6 7 7 8 8
10. RECOMMENDAT IONS 11. REFERENCES 12. GLOSSARY OF TERMS
1.
BACKROUND In 1988, the World Health Assembly through resolution WHA41.28 established the goal of global 'interruption of wild poliovirus transmission' and committed its Member States to this goal. Towards this end, countries implemented the following strategies: (i) achieving high routine immunization coverage of all infants with at least three doses of oral polio vaccine (OPV); (ii) conducting national immunization days; (iii) conducting high-quality surveillance for acute flaccid paralysis (AFP); and (iv) conducting moppingup operations to interrupt the final chains of wild-type poliovirus transmission. In 1999, when it appeared certain that the target of interrupting wild-type poliovirus transmission by the year 2000 would not be met, the World Health Assembly, in resolution WHA52.22, called on all Member States to accelerate eradication strategies by increasing the number and frequency of supplementary immunization activities (SIAs) and intensifying these by adding house-to-house days to the fixed post or booth day. Since then, Afghanistan, India, Pakistan, Nigeria, Niger and Egypt remain the only polio endemic countries. On 15 January 2004, the WHO Director-General, the spearheading partners of the Global Polio Eradication Initiative and health ministers of these countries and others that were re-infected, signed the Geneva Declaration for the Eradication of Poliomyelitis, committing themselves to interrupting the final chains of poliovirus transmission through intensified immunization campaigns. Subsequent meetings were reconvened on 13 January 2005, 4 February 2005, and 30 May 2005 to assess progress in completing the activities set out in the Geneva Declaration and to identify the actions needed to interrupt poliovirus transmission in 2005.
2.
GLOBAL STATUS OF POLIO ERADICATION When the World Health Assembly adopted resolution WHA41.28 and the Global Polio Eradication Initiative (GPEI) was launched in 1988, wild-type poliovirus was endemic in more than 125 countries. By early 2005, the annual number of polio cases reported globally had been reduced by over 99 percent. Additionally, endemic wild polioviruses had been eliminated from all but six countries (Nigeria, India, Pakistan, Niger, Afghanistan and Egypt), demonstrating the success of polio eradication strategies. Following the large polio epidemic of 2003-2004 in west and central Africa, which spread to 16 previously polio-free countries, a massive 'intensified' effort has been launched and is anticipated to stop polio transmission globally in the near future.
3.
STATUS OF POLIO ERADICAT ION IN THE SOUTH-EAST ASIA REGION In WHO’s South-East Asia Region (SEAR), India reported 134 cases in 2004, historically the lowest ever, most of which were from western Uttar Pradesh. Bihar was the other state most affected. As on 30 May 2005, a total of 15 confirmed wild-type1 polio cases with onset in 2005 were reported in India, seven from Bihar, five from Uttar Pradesh, and one each from Jharkhand, Delhi, and Uttaranchal. The latest date of onset in Bihar was 22 February in Siwan district and in Uttar Pradesh it was 24 February in Hathras district. The Greater Mumbai area continues to have low level local transmission of wild poliovirus with positive environmental samples detected on 13
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and 20 April. Genetic data indicates that only two clusters of wild-type 1 poliovirus remain active in 2005, down from 10 in 2003 and four in 2004. Wild-type 3 poliovirus has not been seen in Bihar since January 2004 and the last type 3 case in India was on 24 December 2004 in Rampur district of Uttar Pradesh. Based on a review of the epidemiologic and programmatic data, the India Expert Advisory Group for Polio Eradication (IEAG) met in May 2005 and concluded that polio could be interrupted completely in 2005 by sustaining and improving the innovative approaches being taken to reach every child, including the 'underserved' and 'transit site' strategies. The IEAG at its meeting recommended that India should conduct multistate, sub-national immunization days (SNIDs) in June, August, September and November 2005, NIDs in January and February 2006, and two SNIDs again during March to May 2006. The IEAG also recommended the use of monovalent oral polio vaccine type 1 (mOPV1) in the highest endemic areas in India. The vaccine was developed and licensed in India through a joint collaborative project between an Indian manufacturer, the national regulatory bodies, UNICEF and WHO in a record time of four months. It was used in the highest risk areas during the NIDs in April and May 2005. It will be used in selected areas in some of the subsequent rounds. Efforts are under way to ensure that the vaccine will be available for future use. Implemented with high quality, these rounds and the use of mOPV1 should successfully interrupt the final chains of transmission in India. Political commitment to complete the job remains very high. However, the risk of importation threatens polio eradication in SEAR. After four years of being polio-free, Nepal, in late 2004, reported a wild-type 1 poliovirus from a healthy child who became infected by a visiting polio case from India. Timely and aggressive surveillance and immunization prevented the spread of this virus. In April 2005, importation of wild-type 1 poliovirus from Saudi Arabia and Sudan into an underimmunized population resulted in a poliomyelitis outbreak in Indonesia after a gap of ten years. Circulation of the virus is currently limited to three contiguous districts in West Java province, though intensified surveillance is being conducted to determine the extent of spread, if any. Mopping-up operations were conducted in Banten, West Java and Jakarta provinces targeting 6.4 million children less than five years of age, with the possibility of an extension of these rounds into other provinces as the epidemiology of the outbreak unfolds. The i mportation into Indonesia represents the farthest that the poliovirus has travelled out of Africa in recent times. It illustrates the risk of international spread of the virus into polio-free countries in the world and the threat to the investment that these countries have made in eradicating polio. It is a harsh but timely reminder that no country in SEAR is safe so long as any country in the world has wild-type poliovirus transmission. It highlights the need for countries to maintain high quality surveillance and high levels of routine immunization for infants with at least three doses of OPV.
4.
STATUS OF THE CERTIFICATION PROCESS IN THE SOUTH-EAST ASIA REGION Certification will be conducted on a regional basis three years after the last polio case and in the context of high quality AFP surveillance. Countries will not be individually certified. The International Commission for the Certification of Poliomyelitis in SEAR
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(ICCPE), which serves as the regional certification commission, will certify the Region to be polio free based on the country report submitted to it by the National Certification Committee (NCC) of that country and on site visits by its members to selected countries. It has reviewed and accepted the country report from Bangladesh, Bhutan, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka and Thailand. It recognizes that these countries are free from indigenous polio, and requires an annual update from them. The priority for the Region is to accelerate the certification process in the remaining countries, including India. High quality AFP surveillance is the basis for certification. All countries need to maintain surveillance during certification, OPV cessation and for a time after OPV cessation. The certification process is therefore crucial in ensuring that standards of surveillance are met and maintained and that sufficient population immunity is achieved among all sectors of society, including minorities, the under-served and migrant populations.
5.
STATUS OF LABORATORY CONTAINMENT IN THE SOUTH-EAST ASIA REGION Laboratory containment is a component of certification. A ll countries in SEAR must complete the Phase II activities set out in the 2n d edition of the Global Action Plan (GAP II)1 for the laboratory containment of wild polioviruses. The activities are (i) identification of laboratories with wild poliovirus infectious materials or potential wild poliovirus infectious materials, and destruction of all unneeded materials; (ii) preparation of an inventory of laboratories that retain such materials and report to the ICCPE and institution of enhanced bio-safety level-2 (BSL-2/Polio) measures for safe handling; and (iii) plan for global certification. They will begin one year after polio eradication. In SEAR, 10 countries have an officially appointed National Task Force and a National Plan of Action. Timor-Leste is yet to start containment activities. Implementation of the plan of action has been completed by 9 countries. India will complete the activities in 2006. Six countries (Bhutan, Democratic People’s Republic of Korea, Indonesia, Maldives, Myanmar, Sri Lanka) have submitted the final report for review; Bangladesh, Nepal and Thailand will submit the report shortly. A total of 10 534 bio-medical laboratories in the Region have been surveyed; one laboratory (vaccine production unit, Biofarma, Bandung) is storing wild poliovirus infectious materials and 17 laboratories (three in Sri Lanka, six in Thailand and eight in Bangladesh) are storing potential wild poliovirus infectious materials.
6.
OPV CESSATION - THE FINAL STRATEGY FOR POLIO ERADICATION India is poised to interrupt wild-type poliovirus transmission in 2005. The strategies are well refined and in place. Any slackening of effort or decline in commitment at country, regional or global level would have serious disastrous consequences for the children of India, large numbers of whom would be paralyzed annually, in addition to the threat to the children of other polio-free neighbouring countries. Once regional and global eradication of wild-type poliovirus is confirmed, the final strategy for polio eradication is the synchronous global cessation of use of OPV in the routine immunization programme. Once polio is eradicated, there is no need to immunize against it.
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Although OPV is the only recommended vaccine for eradicating polio, scientific data which have become available since 1999 show that its continued use in a poliofree world will result in paralytic disease due to vaccine-associated paralytic poliomyelitis (VAPP) and outbreaks due to circulating vaccine-derived polioviruses (cVDPVs). VAPP cases will occur at a rate of 2-4 cases per one million birth cohort, wherever OPV is used. WHO estimates that in SEAR the highest burden of VAPP would occur in India at the rate of 2 cases per one million birth cohort. Four polio outbreaks due to cVDPVs have been documented globally since 2000, resulting in a total of 31 polio cases, in Hispaniola (in 2000-2001), the Philippines (in 2001), Madagascar (in 2002) and China (in 2004). A fifth outbreak was described retrospectively in Egypt. While low routine immunization coverage probably contributes to the conditions that give rise to cVDPVs, and mass campaigns with OPV eventually stopped each reported outbreak, it appears that even major improvements in routine polio immunization coverage would be unlikely to prevent future polio outbreaks due to such events. Continued use of OPV would, rarely, lead to prolonged excretion (> 6 months) of a VDPV from a person with a severe primary immunodeficiency syndrome. Theoretically, these 'iVDPVs' could reintroduce poliovirus into the general population. In 40 years of OPV use, 28 iVDPVs had been documented by end-2004, including one in Thailand in 2003. None had been shown to cause secondary cases. Four of these were 'chronic' iVDPVs (excretion > 36 months), all of which occurred in high-income countries. For these reasons, once wild-type poliovirus eradication is confirmed, use of OPV in routine immunization programmes must cease. The Advisory Committee on Poliomyelitis Eradication2 (ACPE), which is the international oversight body for global polio eradication, stated at its meeting in Geneva in September 2004, that continued use of OPV after eradication of wild poliovirus would compromise the goal of a poliofree world. Its use would not be compatible with the global eradication goal. Despite these shortcomings, successful eradication depends on maintaining high coverage with this vaccine until the point of simultaneous OPV cessation. Decreases in OPV immunization coverage prior to the time of OPV cessation would put polio-free countries at risk of wild poliovirus importations and cVDPVs. Unlike smallpox, the eventual cessation of OPV must be synchronized across all countries so that the risk of cVDPV decreases rapidly and uniformly throughout the world, thus ensuring that no country is at risk of importing a cVDPV from an area where OPV use continues. The international oversight bodies that guide the Global Polio Eradication Initiative concluded in 2003 and 2004 that OPV cessation should occur as soon as possible after the interruption of wild poliovirus transmission globally, while population immunity against polio and surveillance sensitivity for acute flaccid paralysis remain high3. WHO estimates that following the last circulating wild-type poliovirus, the entire process of cessation, i.e. from certification to cessation to the post-OPV era, could take at least eight years for completion.
7.
RISKS ASSOCIATED WITH OPV CESSATION There are risks associated with OPV cessation. There is an estimated 65-90% chance of a cVDPV outbreak occurring somewhere in the world during the first year after simultaneous OPV cessation. This risk will fall to 5-15% by the end of the second year, and will reduce further to 1-5% by the end of the third year4.
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The medium and long-term risks, and also the greatest threat to polio eradication globally, is the chance re-introduction of a wild, vaccine-derived or Sabin strain of poliovirus from a polio vaccine manufacturing site, a research facility or a diagnostic laboratory. This risk is low and will diminish further as all countries fully implement and verify appropriate bio-containment of polioviruses. Achieving appropriate containment of all polioviruses will be extremely important given that the potential harmful consequences of a poliovirus re-introduction will increase substantially as poliosusceptible individuals accumulate after OPV cessation. The risk of reintroduction of a vaccine-derived poliovirus from an iVDPV is still lower for the reasons noted above. These risks, though small, can be further reduced through international implementation of appropriate risk management strategies before, during and after OPV cessation. Implementation of these risk management strategies – or prerequisites – will require close oversight by national policy makers. WHO guidance on OPV cessation can be found in the document WHO/POLIO/05.02, entitled Cessation of routine oral polio vaccine (OPV) use after global polio eradication: Framework for National Policy Makers in OPV-Using Countries.
8.
PRIORITIES FOR SEAR The regional priorities are: • • Interrupting wild poliovirus transmission in India; this is the over-riding priority. Confirming polio eradication through regional certification three years after the last polio case in the Region and appropriate bio-containment of all polioviruses. Maintaining highly sensitive AFP surveillance for all polioviruses in order to achieve certification, and for OPV cessation. AFP surveillance reviews will be conducted as p art of the process of enhancing surveillance sensitivity and quality. In SEAR countries which rely on an externally funded network of surveillance medical officers or surveillance officers, maintenance of these networks will be critical. Increasing routine OPV3 coverage uniformly in all countries at the sub-national level. Ensuring that every country has a polio outbreak response plan. Establishing procedures for synchronized OPV cessation in the Region, including destruction of trivalent OPV (tOPV) stocks, and assisting Member States in establishing a long-term routine immunization policy. Ensuring that a stockpile of monovalent OPV (mOPV) against all three wildtype polioviruses is established in a country of SEAR. Such a stockpile would be readily accessible to the countries of the Region.
•
• • •
•
9.
ISSUES
9.1 Interrupting the Final Chains of Wild-type Poliovirus Transmission in India In polio-endemic areas in north India the transmission of polioviruses is particularly efficient. Mass campaigns are required to reach more than 95% of children with OPV in
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the infected areas, every six weeks until transmission stops. The intensity of these campaigns may have to be continued into 2006 in order to consolidate the progress to date. To interrupt the remaining chains of transmission of wild-type 1 poliovirus, a new monovalent OPV was developed and licensed in India. This vaccine was used in the highest risk areas during the mass campaigns in April and May 2005. The benefits to the programme are expected to be decisive.
9.2 Strengthening Surveillance for Polio Cases and Polioviruses Surveillance that does not meet certification standards at the sub-national level, and that misses minority, migrant and floating populations, could fail to detect ongoing poliovirus transmission. Surveillance for acute flaccid paralysis must be enhanced in all countries, especially where importations have recently occurred, those areas recently or currently affected by conflict and/or with uncertain population figures. Enhanced surveillance must also be sustained over a period of years that will encompass certification and OPV cessation. This will require sustained commitment at the highest political levels.
9.3 Preparing for the Synchronous Cessation of Oral Poliomyelitis Vaccine Use The Advisory Committee on Polio Eradication (ACPE) has recommended synchronous cessation of the use of OPV as early as three years after interruption of wild-type poliovirus transmission worldwide, as continued use of the live attenuated polioviruses contained in that vaccine would ultimately be incompatible with eradication. Ceasing the use of the OPV will eventually eliminate poliomyelitis outbreaks due to cVDPVs and VAPP. Safely stopping use of oral poliomyelitis vaccine will require: (i) confirmation of interruption of transmission of wild-type poliovirus globally, (ii) appropriate containment of all poliovirus strains (wild-type, vaccine-derived and Sabin) in laboratories and vaccine-production facilities, (iii) a WHO/UNICEF-managed stockpile of monovalent oral poliomyelitis vaccines with internationally agreed mechanisms for their use, (iv) continued poliovirus surveillance and notification capacity that meet international standards globally, (v) processes for synchronously stopping use of oral poliomyelitis vaccine globally, and (vi) decisions by all countries using oral poliomyelitis vaccine on their long-term poliomyelitis immunization policy for the period following cessation of use of oral vaccine.
9.4 Ensuring Sufficient Financing The planned schedule of mass campaigns in India during the remainder of 2005 is funded, though the flow of funds requires constant adjustment. Immunization activities for 2006 are partially funded. Additionally, countries that are vulnerable to importations also require assistance in funding mass campaigns and enhancing their surveillance. Closing these gaps, identifying funds for the certification activities, including enhanced surveillance, required till the end of 2008, and ensuring funding for eventual cessation of the use of oral poliomyelitis vaccine, especially the building of a stockpile of mOPV, will require the confirmation of multi-year pledges for 2004-2008 and the participation of other international development donors.
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9.5 Injectable Polio Vaccine (IPV) Each OPV-using country must decide whether or not it will stop all routine immunization against polio after OPV cessation. At that time, the injectable polio vaccine (IPV) would be the only option available for such countries. WHO recommends that OPV-using countries do not routinely introduce IPV. However, if a country decides to continue routine immunization with IPV5, the following factors should be taken into consideration: costs and benefits, the impact on other disease control programmes, major programmatic implications of IPV introduction – such as the need to increase cold chain capacity, changing the pertussis component of combination vaccines, use of vaccine with a different preservative, and the marginal reduction of the already-small risks associated with OPV cessation. WHO is currently assisting some polio-free countries in evaluating the potential role of IPV in their national immunization programme, and will continue to review the role of IPV as additional data are collected on the risks associated with OPV cessation.
10. RECOMMENDATIONS (1) Every effort should be made to interrupt the final chains of transmission of polio in India in 2005. (2) All Member States should enhance AFP surveillance to guide the interruption of the final chains of transmission, certify eradication, and detect potential importation and cVDPVs. They should ensure that the targets for the surveillance indicators are exceeded at the sub-national level and that minority, migrant and floating populations and conflict-affected areas are periodically assessed by the surveillance system. As enhanced surveillance must be sustained over several years, this will require resource commitments from Member States. (3) Every Member State should fully implement and verify appropriate containment of wild and vaccine-derived polioviruses and prepare for Sabin-virus containment. (4) Member States should use the Reaching Every District (RED) approach to increase and maintain high OPV3 coverage (>90%) at district level, to ensure that minority, conflict-affected, migrant and floating populations are covered. This will minimize the risk of spread of imported polio virus and the emergence of cVDPV. The RED approach is a key component of the Global Immunization Vision and Strategy (GIVS), which is WHO/UNICEF’s long term global strategy to fight vaccine preventable diseases. The recently concluded World Health Assembly endorsed the GIVS. (5) As a demonstration of their commitment and state of preparedness, all Member States should have an outbreak response plan that is reviewed and approved at the highest political levels. (6) Every Member State should decide – based on analysis of risks, benefits and opportunity costs – whether or not to stop all routine immunization against polio after OPV cessation. After cessation, inactivated polio vaccine would be the only option for continued routine immunization. (7) Every Member State should develop a plan and mechanisms for the eventual cessation of use of OPV in its routine immunization programme and destruction of remaining stocks of trivalent OPV.
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11. REFERENCES 1. 2. 3. 4. 5. 6. 7. WHO Global Action Plan for Laboratory Containment of Wild Polioviruses (GAP II), Second edition. World Health Organization, Geneva, Switzerland, 2003. (WHO/V&B/03.11) Hull HF, Lee JW. Sabin, Salk or sequential? The Lancet. March 1996. Conclusions and Recommendations of the Advisory Committee on Polio Eradication (ACPE), Geneva, Switzerland, 21-22 September 2004. WHO Informal Consultation on Identification and Management of Vaccine-derived Polioviruses. September 2003, Geneva, Switzerland. Duintjer-Tebbens RJ et al. Risks of Paralytic Disease due to Wild or Vaccine-derived Poliovirus after Eradication (Submitted). WHO presentation at 3rd WHO/UNICEF Informal Consultation with IPV and OPV Manufacturers. June 2004, Geneva, Switzerland. WHO Cessation of routine oral polio vaccine (OPV) use after global polio eradication: Framework for National Policy Makers in OPV-Using Countries. (WHO/POLIO/05.02)
12. GLOSSARY OF TERMS ACPE AFP BSL cVDPV GIVS GPEI ICCPE IEAG Advisory Committee on Poliomyelitis Eradication acute flaccid paralysis bio-safety level vaccine-derived polioviruses that circulate and may cause paralytic poliomyelitis Global Immunization Vision Strategy Global Polio Eradication Initiative International Certification Commission for Polio Eradication in SEAR: this is the regional certification commission. India Expert Advisory Group for polio eradication: a panel of national and international polio experts which meets ad hoc to review progress in India and advise Government of India and partners on most appropriate strategies to achieve rapid interruption of polio transmission. inactivated polio vaccine immunodeficient excretors of vaccine-derived polioviruses monovalent oral polio vaccine monovalent oral polio vaccine type 1 National Certification Committee for Polio Eradication National Immunization Days oral polio vaccine reaching every district strategy WHO’s South-East Asia Region
IPV iVDPV mOPV mOPV1 NCC NIDs OPV RED SEAR
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SNIDs tOPV VAPP
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Sub-national Immunization Days trivalent oral polio vaccine vaccine-associated paralytic poliomyelitis: paralytic poliomyelitis with residual weakness 60 days after onset of paralysis and having adequate stool specimens test negative for wild-type poliovirus in a WHO accredited laboratory but positive for vaccine virus and the case is evaluated by an expert committee which considers additional data such as exposure history and potential epidemiological link to confirmed polio cases. vaccine-derived polioviruses: these are viruses that show a greater than 1% genetic drift from Sabin (vaccine) virus. World Health Assembly World Health Organization
VDPV WHA WHO
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