Revelation of an important weakness in polio elimination efforts in Nigeria: a descriptive cross-sectional study of nomadic dynamics in Sokoto and Taraba States, May 2013

Introduction: Operational gaps in the Global Polio Eradication Initiative implementation had been partly responsible for inadequate population immunity and the continued transmission of wild poliovirus in Nigeria before the African Region was declared polio-free in 2020. Missed opportunities to provide services in nomadic populations due to frequent mobility, lack of inclusion in microplans and the remoteness of their settlements were the major challenges. During May 2013 we conducted immunization outreach to nomadic and other underserved communities in Rabah LGA, Sokoto state, and Ardo Kola LGA, Taraba state, in Nigeria to identify and vaccinate children missed during supplemental immunization activities while identifying missed acute flaccid paralysis cases. Methods: An enumeration checklist and data collection instruments on Android cell phones were used to capture socio-demographic data and GPS coordinates on nomadic settlements, households, number of children aged <5 years, children previously missed for vaccination and their locations. Local guides led trained enumerators to underserved communities for the enumeration and vaccination. Data were analyzed using Microsoft Excel 2007. Results: A total of 324 settlements were listed for the two states, and 111 (34.3%) of these were identified as missed when compared with micro-planning for the most recent SIA. In these settlements, 3,533 households and 9,385 children aged <5 years were listed. We administered oral poliovirus vaccine to all 1,946 missed children during the recent or any supplemental immunization activities. Of these, 527 (27.1%) had never been vaccinated. We found no missed acute flaccid paralysis cases. Conclusion: Nomadic populations continue to be underserved, especially for vaccination services. This results in pockets of populations with low herd immunity and increased risk for poliovirus transmission. Community leaders and nomadic settlements should be included in the micro-planning of all supplemental immunization activities to ensure all children receive vaccination services.