Perspectives from the Global Poliomyelitis Eradication Initiative
H.F. Hull,* C. de Quadros,** J. Bilous,*** G. Oblapenko,**** J. Andrus,***** R. Aslanian,****** H. Jafari,****** J.-M. Okwo Bele,******* & R.B. Aylward*
Ten years after the year 2000 target was set by the World Health Assembly, the global poliomyelitis eradication effort has made significant progress towards that goal. The success of the initiative is built on political commitment within the endemic countries. A partnership of international organizations and donor countries works to support the work of the countries. Interagency coordinating committees are used to ensure that all country needs are met and to avoid duplication of donor effort. Private sector support has greatly expanded the resources available at both the national and international level. At the programmatic level, rapid implementation of surveillance is the key to success, but the difficulty of building effective surveillance programmes is often under estimated. Mass immunization campaigns must be carefully planned with resources mobilized well in advance. Programme strategies should be simple, clear and concise. While improvements in strategy and technology should be continuously sought, changes should be introduced only after careful consideration. Careful consideration should be given in the planning phases of a disease control initiative on how the initiative can be used to support other health initiatives.
The target to eradicate poliomyelitis by the year 2000 was set by a World Health Assembly resolution in 1988, which specified that global eradication was to be achieved within the Expanded Programme on Immunization (EPI) and within the context of strengthening primary health care (1). Since that target was set, significant progress has been achieved. However, global poliomyelitis eradication can be achieved on time only if the necessary political support and financial resources are secured. While success is not yet assured, the lessons learned during the past 10 years are relevant to the planning of future eradication initiatives. This article summarizes the perspectives from experiences with the poliomyelitis initiative in the hope that other diseases can be eradicated in the most efficient manner possible.
Strategies for Poliomyelitis Eradication
WHO, building on the initial successes in the Americas, defined four principle strategies for global poliomyelitis eradication: high routine immunization coverage -- countries should achieve 90% immunization coverage in all districts by the year 2000; national immunization days (NIDs) -- during these mass campaigns, all children aged less than 5 years, irrespective of their prior immunization status, should receive two doses of oral poliovirus vaccine (OPV) in rounds spaced approximately 1 month apart; surveillance for acute flaccid paralysis (AFP) -- all AFP cases must be reported with clinical, epidemiological and laboratory investigation; and mopping-up immunization -- house-to-house immunization campaigns should be conducted in high-risk areas identified through disease surveillance. These strategies have been discussed in detail elsewhere (2,3).
Once wild poliovirus transmission has been interrupted, eradication must be certified by the Global Commission for the Certification of Poliomyelitis Eradication, which first met in 1995. Under the auspices of this commission, national committees are convened in all countries to collect evidence conclusively demonstrating that poliomyelitis has been eradicated. The certification process focuses primarily on the performance of the surveillance system, but also reviews information on the performance of the immunization system and documentation of preparedness to control any imported cases that may occur. Although each country must provide individual data, certification is on a WHO regional basis.
Progress in Implementing Strategies
Routine coverage with three doses of OPV worldwide has remained above 80% since 1990. Coverage is lowest in the African Region, where 12 countries are unable to immunize even 50% of infants born. As of March 1998, at least one round of NIDs had been conducted in all polio-endemic countries with the exception of the Democratic Republic of the Congo, Liberia, Sierra Leone, and Somalia. In 1997, more than 450 million children were immunized during NIDs in 80 countries worldwide. AFP surveillance has been implemented in 142 countries. Ten polio-endemic countries did not have national AFP surveillance as of March 1998. The rate of AFP cases reported is substantially below the target of 1 per 100,000 annually in the African Region, where AFP surveillance is in the early phases of implementation. In the South-East Asia Region, surveillance is improving rapidly, following the posting of a large cadre of surveillance medical officers in India.
Disease Incidence and Challenges
The number of poliomyelitis cases reported to WHO declined by 88% between 1988 (35 252 cases) and 1996 (4074 cases). As of April 1998, 3376 cases were reported for 1997 (4). However, reporting is incomplete and the final total for 1997 will approach 4000 cases. Poliomyelitis eradication was certified in the Americas in 1994, the last case being reported from Peru in September 1991 (5). At the time of writing, one year had elapsed since the last case of poliomyelitis was reported from the WHO Western Pacific Region. In the European Region, six virologically confirmed cases were reported in 1997, all from south-eastern Turkey. West and central Africa remain heavily endemic, with the Democratic Republic of the Congo and Nigeria serving as major reservoirs of wild poliovirus. South Asia is the other major global reservoir with Afghanistan, Bangladesh, India, Nepal and Pakistan remaining heavily endemic. Wild poliovirus, type 2, was identified in 1997 from only three countries -- Afghanistan, India and Pakistan.
The progress achieved proves that existing technology and the WHO-recommended strategies are sufficient to eradicate poliomyelitis worldwide. The challenges that remain, however, are significant. Eradicating the disease in the remaining endemic countries will be particularly difficult because of their relative poverty, poor health infrastructure, difficult geography, dispersed populations, and ongoing armed conflict. In the most difficult countries, a substantial part of the cost of eradication must come from external sources. WHO estimates that in excess of US$ 1000 million of funds from international sources will need to be spent in the period 1998-2005 to stop wild poliovirus transmission and then certify global eradication. Mobilizing these resources and maintaining the political commitment to complete the work in the face of declining incidence are the major challenges that face the initiative. Additional challenges are the containment of laboratory strains of wild poliovirus and reaching consensus on a strategy for stopping immunization after eradication.
Lessons for Future Eradication Initiatives
Progress towards poliomyelitis eradication has been rapid in the last 10 years, faster than some would have predicted. Within that progress, however, are both successes and failures. Just as smallpox eradication served as the foundation for poliomyelitis eradication, the successes and failures of the latter offer lessons for future eradication and elimination initiatives.
The single most important factor in the continuing success of poliomyelitis eradication is political commitment within the endemic countries. Eradication activities are conducted by the countries with the assistance of the international community. In the Americas, 80% of the cost of eradication was borne by the countries (6), while in China and Indonesia, that proportion was over 90%. The financial and human resources required for poliomyelitis eradication are, however, normally beyond the capacity of the ministry of health. Successful mass immunization campaigns require multisectoral cooperation with the involvement of the ministries of finance, transport, information, women's affairs and religious affairs, among others. The military often provides necessary transport and communication facilities. Achieving this level of intersectoral support usually requires the involvement of the head of state. Fortunately, visible and successful immunization campaigns are politically attractive and bring home the message that good health is good politics. For poliomyelitis eradication to succeed in heavily endemic countries, political commitment must be sustained for a period of at last 3-5 years.
However, eradication cannot be achieved in most polio-endemic countries without the assistance of the international community. Partnerships must be forged to ensure that sufficient resources are made available to the endemic countries. Global poliomyelitis eradication is possible because of the partnership of the governments of the endemic countries with WHO, UNICEF, Rotary International, AUSAID, CIDA, DANIDA, DFID, USAID and the governments of Japan, Norway and other countries; CDC and JICA provided critical technical support. The building of a successful coalition takes time. Each organization brings its particular strengths, and understanding the culture of each organization is vital.
Partnership is made manifest through Inter-agency Coordination Committees (ICCs), particularly at the national and regional level. Regular meetings of the ICC partners and representatives of the governments review the human and financial requirements for the eradication activities. The function of the ICCs is to ensure that all needs are met without duplication of effort. Partnership is also very much in evidence at annual meetings of the Global and Regional Technical Consultative Groups, during which technical staff and representatives of partner organizations meet to review progress and recommend changes in technical policy. Transparency regarding changes in programme policy facilitates the funding process.
Although the majority of financial support for poliomyelitis eradication has come from governments, significant support from the private sector has clearly accelerated the initiative. The most visible example is Rotary International, which by the end of the initiative, would have contributed more than US$ 400 million in private funds and millions of hours of volunteer time. Additional private sector support has come from businesses which paid for advertising, provided transportation, procured local commodities, and provided meals for vaccinators in the field. Individual volunteers have supported NIDs through social mobilization, transport of vaccine and vaccination staff, and free service at immunization posts. The eradication initiative has also benefited from the advocacy efforts of Rotarians and other influential persons who mobilized political support and financial resources in both endemic and polio-free countries.
The theme of partnership also extends to the area of intercountry and interregional cooperation. Microbial agents do not respect international boundaries. Since border areas are often poorly served by many government services including health, one solution to cross-border transmission has been multi-country NIDs; operation MECACAR is one such example, in which 19 countries coordinated their NIDs and immunized 60 million children (7). Specific cross-border immunization campaigns have been conducted where migratory populations have been an important reservoir. Rapid exchange of epidemiological information across international borders and interregional boundaries is vital.
Accelerated development of reliable surveillance is vital to the success of the initiative (8). For example, several countries that had apparently stopped poliovirus transmission did not have surveillance data to demonstrate that this was the case. As a result, NIDs continued for several years more than was, perhaps, necessary. In other countries, transmission of wild polioviruses might have been interrupted sooner if surveillance data had been available to identify high-risk populations. Since the cost of surveillance is less than a tenth of the total cost of poliomyelitis eradication, rapid development of surveillance systems should be seen not just as a necessity, but also as a cost-saving measure.
The difficulty of establishing surveillance is often underestimated. Surveillance is much less visible than immunization campaigns and is often perceived as a lower priority. Delays in developing surveillance systems result from a number of factors. Establishing AFP reporting and building the capacity for case investigation typically takes several years. Physicians and other clinical health care personnel who are likely to see cases must be trained to the rationale and methods for AFP surveillance. Active surveillance through weekly visits to health facilities that are most likely to see such cases are usually required. Case investigation teams must be trained and provided with transport and travel allowances. Electronic communication does not substitute for the face-to-face meetings required to build effective teams. In the laboratory network, training laboratory staff and retaining them is a continuing challenge. A stock of reagents and disposable supplies must be maintained for all network laboratories. Although every attempt was made to use existing, functional virology laboratories, capital equipment purchases are often necessary. Assessing equipment needs, securing funds, procuring, and shipping are all time-consuming activities.
Monitoring the quality of surveillance through the use of standard, internationally comparable performance indicators is central to success. Reporting must be complete and timely to permit effective action. As poliomyelitis incidence decreases, reporting of AFP cases becomes increasingly important because these could possibly be poliomyelitis. Surveillance indicators were developed to monitor the effectiveness of the surveillance system. The most important of these are the AFP rate, the percentage of AFP cases with two adequate stool specimens, and the timeliness and completeness of reporting by district. Supervisory visits to the field are necessary and often reveal problems and solutions that could not be appreciated from the central level. Laboratory performance must also be measured in a similar, but more comprehensive manner. Laboratories must be formally accredited and regularly demonstrate their proficiency with blinded samples. Useful laboratory process indicators are the percent of specimens with non-polio enteroviruses and the percent of specimens analysed within 28 days of receipt of the sample.
The availability of simple and safe technology has been central to the successful implementation of poliomyelitis eradication strategies. Because OPV is administered orally, many countries have used trained volunteers as vaccinators (9). This approach greatly expands the work force available to conduct NIDs, increases the speed with which NIDs can be conducted, and raises the coverage achieved. The ultimate volunteer vaccinator is the head of state. The opportunity for high-level politicians to be filmed immunizing children both increases the political support for the initiative and sends a powerful message to government and health workers alike.
Successful immunization campaigns require adequate planning and budgeting for logistics and social mobilization, extending down to the district level. Campaigns conducted without sufficient lead time and the necessary planning and resource mobilization have been substandard. With sufficient forward planning and coordination with donors, multiyear grants were made in some countries, permitting technical staff to focus on programme implementation rather than fundraising. In planning, one must also recognize that the cost of bringing together the child and the intervention greatly exceeds that of the intervention itself. The cost per child per year for two doses of OPV is approximately US$ 0.20. However, the average cost of training, social mobilization and operations to deliver that vaccine is US$ 0.80 per child. In the most difficult countries, operational costs can rise to US$ 3 per child immunized.
Technological changes that simplify logistics and reduce costs produce the greatest advantages to the initiative. For smallpox, these were the jet injector and then the bifurcated needle. One important technological advance for the poliomyelitis eradication initiative is the individual vaccine vial monitor (VVM), a thermosensitive marker which changes colour when exposed to heat. VVMs allow a vaccinator with minimal training to tell at a glance if a vaccine vial has been exposed to excessive heat. They increase confidence that the vaccine is potent at the time of administration and permit OPV to be taken out of the cold chain. The genetically engineered murine L20B cell line is another new technology that is currently being introduced into network laboratories. This change is expected to reduce the workload and markedly increase the reliability of cell culture for the identification of polioviruses. Technology, which was proposed but not incorporated into the eradication initiative, include using IPV and stabilizing OPV with deuterium oxide. These technical changes provided only marginal improvements in efficiency and/or could not be made available in time to make a significant impact. The search for improved technology should continue as the initiative progresses, but efforts should promote quantum leaps rather than incremental gains.
Similarly, strategies must be continuously reviewed to improve efficiency and, where possible, make changes that reduce cost and simplify logistics. Changes in strategy that have been adopted by the poliomyelitis eradication initiative include the following: an emphasis on hospital-based, active surveillance to increase AFP case detection; elimination of routine collection of specimens from case-contacts (benefits were small while overloading laboratory capacity); and a de-emphasis of localized outbreak response immunization (scientific review indicated minimal impact on virus transmission). Strategists must keep in mind that frequent or unnecessary changes in strategy produce confusion. Complexity must also be avoided since activities are conducted by field staff in developing countries. Accordingly, strategies must be simple and consistent and changed only after careful consideration.
While other health initiatives may benefit from the eradication initiative, requests to combine other activities with the eradication activities must be considered carefully. In the course of the poliomyelitis eradication initiative, for example, vitamin A capsules have been administered during NIDs, while measles vaccine and tetanus toxoid have been administered to selected high-risk populations, and dracunculiasis searches have been conducted in a major guinea-worm reservoir. However, caution must be exercised so that the objectives of the eradication activity are not compromised. Thorough planning is necessary so that adequate human and financial resources are secured for the additional tasks.
Recently there has been considerable debate over the impact of poliomyelitis eradication activities on primary health care (10). The Taylor Commission reviewed the issues in the Americas after eradication was achieved there (11); the report was supportive, but the sociological approach taken provided insufficient documentation to resolve the debate. Another study has been started, but the results are unlikely to be available until the final phases of the initiative. Although poliomyelitis eradication has increased immunization coverage and improved the quality of services in countries with poorly developed immunization programmes and sustained the level of coverage in countries with good immunization services, this information has not been systematically collected or disseminated. Future initiatives should include early documentation of all the benefits including reduced morbidity and mortality. It may, therefore, be useful to consider during the planning phases the benefits to other health systems from eradication activities.
While the last case of poliomyelitis is still several years in the future, the success of the global poliomyelitis eradication initiative can serve as a model for future disease eradication and elimination initiatives. As strategies for those initiatives are being defined and consensus to move forward is built, political support and funding for the final and most difficult phase of eradication must continue. Since failure of the poliomyelitis (or dracunculiasis) eradication initiatives would jeopardize support for any future eradication initiative, significant challenges must be met. The global poliomyelitis eradication initiative remains on track and global certification is expected shortly after the turn of the century. When that occurs, every child in every country will be free of the risk of poliomyelitis forever.
* World Health Organization, Geneva, Switzerland.
** Pan American Health Organization, Washington, DC, USA.
*** WHO Regional Office for the Western Pacific, Manila, Philippines.
**** WHO Regional Office for Europe, Copenhagen, Denmark.
***** WHO Regional Office for South-East-Asia, New Delhi, India.
****** WHO Regional Office for the Eastern Mediterranean, Alexandria, Egypt.
******* World Health Organization, Harare, Zimbabwe.
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