Academic journal article Bulletin of the World Health Organization

Supplementary Polio Immunization Activities and Prior Use of Routine Immunization Services in Non-Polio-Endemic Sub-Saharan Africa/Campagnes De Vaccination Antipoliomyelitique Supplementaire et Recours Anterieur Aux Services De Vaccination De Routine En Afrique Subsaharienne Non-Polio-endemique./Actividades Suplementarias De Inmunizacion Contra la Poliomielitis Y USO

Academic journal article Bulletin of the World Health Organization

Supplementary Polio Immunization Activities and Prior Use of Routine Immunization Services in Non-Polio-Endemic Sub-Saharan Africa/Campagnes De Vaccination Antipoliomyelitique Supplementaire et Recours Anterieur Aux Services De Vaccination De Routine En Afrique Subsaharienne Non-Polio-endemique./Actividades Suplementarias De Inmunizacion Contra la Poliomielitis Y USO

Article excerpt

Introduction

Since the late 1980s, use of supplementary immunization activities

(SIAs) has been a key strategy of the Global Polio Eradication Initiative (GPEI). SIAs are mass vaccination campaigns that aim to administer additional doses of oral poliovirus vaccine (OPV) to each child aged < 5 years, regardless of their vaccination history. In doing so, SIAs attempt to remedy the limited ability of routine immunization services to reach at-risk children with the number of OPV doses required to generate immunity. (1,2) In many countries, SIAs have largely contributed to the 99% global reduction in the incidence of paralytic poliomyelitis observed since the 1988 launch of the GPEI. (2-4)

Despite the central role of SIAs in eradication efforts, setbacks in the GPEI have been attributed to low-quality SIAs. (5) Target dates for eradication have repeatedly been pushed back and, at present, transmission of wild poliovirus remains endemic in Afghanistan, Nigeria and Pakistan. Four countries where circulation of wild poliovirus had stopped (Angola, Chad, Democratic Republic of the Congo and South Sudan) have been labelled as having "re-established polio transmission" and several other countries previously considered to be "polio free" have reported cases of acute flaccid paralysis due to wild poliovirus strains originating from northern Nigeria. (6,7) A wild poliovirus "importation belt" thus stretches from Senegal to the Horn of Africa. To achieve eradication, the 2010-2012 GPEI strategic plan sets strict targets of > 90% coverage for each SIA conducted in the importation belt. Even in such highly immunized populations, however, outbreaks may still occur if much lower coverage is achieved for particular subpopulations. (8) In particular, the influence of SIAs on population-level immunity against polio may be lowered if children who do not access routine immunization services (and are thus less likely to be immune to polio and other vaccine-preventable diseases) also participate less frequently in SIAs.

Very limited data on patterns of SIA participation are available that consider past use of routine immunization services. In a study of the 1997 Madagascar SIA, Andrianarivelo and colleagues (9) reported significantly increased SIA-associated immunity among children who had not used routine immunization services or had missed routine OPV doses. Currently collected data on SIA coverage do not include an assessment of the immunization history of children who were not vaccinated during SIAs. The effectiveness of polio SIAs at supplementing routine immunization services in non-polio-endemic sub-Saharan African countries is thus not known. In this article, we test the hypothesis that children who did not use routine immunization services before an SIA were less likely to participate in that SIA, compared with children who were users of routine services. We also measured SIA participation among users of routine immunization services who were compliant with the routine OPV immunization schedule, compared with users who were non-compliant.

Methods

Data collection and study groups

We used three data sources: Demographic and Health Surveys (DHSs), Multiple Indicator Cluster Surveys (MICSs) and the 2010 Mobile Technology for Community Health (MoTeCH) survey (Appendix A, available at: http://www.columbia.edu/-sh2813/appendix-02292012sh.pdf). The first two sources are nationally representative household-based surveys conducted, on average, every 3-6 years in several sub-Saharan countries. The MoTeCH survey is a household-based survey conducted among women residing in the Kassena-Nankana East and West districts in Ghana's Upper East Region. In all surveys, data on participation in SIAs and use of routine immunization services were collected in a similar manner. Mothers were asked to provide vaccination information for their surviving children < 5 years old. (10-12) They were first asked whether their child had ever had a health card. …

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