Global public health mandates in a diverse world: the polio eradication initiative and the expanded programme on immunization in sub-Saharan Africa and South Asia
Introduction
In 1988, encouraged by the elimination of poliomyelitis in Americas, the World Health Assembly passed the resolution for global polio eradication by the year 2000 [1]. Polio eradication programs were launched in many South Asian countries in 1995 and in most sub-Saharan African countries in 1996 [2], [3], [4], [5], [6]. The global polio eradication program employed the following strategies to ensure universal coverage of polio vaccination: (a) routine immunization of infants with at least three doses of polio vaccination under the Expanded Program of Immunization (EPI); (b) intensified efforts such as National Immunization Days (NIDs) to deliver polio vaccine through mass campaigns to all children less than 5 years; (c) surveillance of acute flaccid paralysis to detect transmission of poliovirus; and (d) house-to-house mopping-up immunization campaigns in the final stages of the program [5], [7]. While the goal of global polio eradication by the year 2000 was not reached, WHO expects that the transmission of wild poliovirus will soon be interrupted [8].
The polio eradication initiative has achieved a reduction in the number of poliomyelitis cases and deaths to a minute fraction of the 1988 levels [8], [9], substantially decreasing or eliminating the risk of polio not only in high-income, but also in middle- and low-income countries. In addition to this direct benefit, indirect benefits were anticipated; in particular, to increase the levels of, and equity in, coverage of non-polio EPI vaccinations administered through routine health services by strengthening of health systems, by increasing awareness about immunization, and by enhancing political commitment for immunization [7], [10], [11], [12], [13], [14]. The indirect benefits actually achieved by the campaign include widespread vitamin A distribution; enhanced global surveillance capacity; and improved worldwide cooperation between enterovirus laboratories [11], [13]. The evidence regarding effects on non-polio, routine immunisation services remains controversial [15]. Some researchers raised concerns that polio mass campaigns have adversely affected the non-polio EPI vaccine coverage by disrupting the routine health service delivery [11], [16], [17], [18], [19]. Others argue that the effects of declining economies, or of major health system reforms, were responsible for lower EPI antigen coverage rates in some countries or population segments [15].
The conceptual framework for the hypotheses and analyses of the study is given in Fig. 1. The study’s conceptual framework draws on [20] and other works [10], [14], [18], [21], [22], [23].
Implementation of a polio eradication initiative in addition to ongoing routine immunization requires full commitment and close coordination of political executives, civil services, health as well as non-health departments, non-government and community-based organizations at different levels (national, regional, district and village) as shown in Fig. 1. However, on the supply-side, the capacity for carrying out different activities across various actors and across different levels may depend on various factors—political [24], organizational [25], managerial, financial, social and cultural—that may result in wide variation in polio and non-polio vaccination during the campaign. On the demand-side, the effect of immunization programs depends on social and geographical aspects in which the programs operate [21].
Socio-economic inequities within a community may also influence health outputs, resulting in parallel inequities in vaccination coverage rates, unless deliberate efforts are made to reduce the inequities [26]. The health systems in different countries may have different capacities and political will to reach the most disadvantaged children. Hence, wide variations in the impact of polio initiative on changes in social equity in immunization coverage may be expected.
Substantial additional inputs have gone into vaccination-related services and infrastructure during the intensified polio eradication efforts [7], [8], [10], [11], [12], [13], [14]. However, given the diverse supply and demand side determinants of vaccination outcomes in Asian and sub-Saharan African countries, the effect of polio eradication initiative on routine immunization may be different with important implications for sustainability of the EPI. Once the circulation of wild poliovirus will have been terminated, intensified efforts in vaccination may cease, and the extra inputs into the EPI may no longer be available. Given this constraint, it is unclear whether routine immunization programs will in future still be able to ensure population immunity against polio, as well as equitable coverage of other EPI vaccines. To examine this question, we assessed: (a) whether the implementation of NIDs was associated with increasing the EPI coverage rates, thus compensating for negative effects of economic decline and other factors on the EPI coverage and equity; (b) whether today’s routine EPI services, combined with intensified efforts such as NIDs, are ensuring universal and equitable vaccine coverage; and (c) whether in post-polio eradication scenario, additional efforts would be required to sustain universal and equitable EPI coverage.
Section snippets
Study settings
We included three South Asian and twelve sub-Saharan African countries listed in Table 1. Our selection was determined by the availability of comparable data “before” and “after” the implementation of NIDs under the polio eradication program. The countries in the study are characterized by mid- to lower levels of health system performance [27], and substantial social challenges to immunization coverage [28] (see Table 1 for details). India, Nigeria and Niger have persistent wild poliovirus
Changes in access to polio and non-polio EPI vaccines
Table 2 shows the changes in polio-1 and EPI-1 coverage between pre- and post-interventions surveys. Before the introduction of NIDs, polio-1 varied between 36% in Niger to almost universal coverage in Kenya, Malawi, Rwanda, Tanzania, and Zimbabwe (more than 90%). In the post-intervention surveys, polio-1 varied between 51% in Niger to 99% in Nepal. While significant increases in polio-1 coverage were seen in six countries (Nepal, India, Niger, Cameroon, Cote d’Ivoire and Ghana), it declined
Discussion
The main conclusions of the study are that: (a) the implementation of NIDs was associated with an increase in the EPI in some countries—India, Nepal, Cote d’ Ivoire and Ghana—and a decrease in some—Nigeria and Zimbabwe. In the remaining countries the change in the EPI was equivocal; (b) although in some countries NIDs were associated with a reduction in social inequities in the EPI, in the majority of the countries, social inequities persisted; and (c) as intensive efforts through NIDs may come
Acknowledgements
The authors acknowledge the useful comments and suggestions of the anonymous reviewers. The findings, interpretations and conclusions expressed in this paper are entirely those of the authors alone and do not necessarily represent the views of the institutions they work for.
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