Vaccination is an important and cost-effective disease prevention and control strategy. Despite progress in vaccine development and immunization delivery systems worldwide, populations in areas of conflict (hereafter, “conflict settings”) often have limited or no access to lifesaving vaccines, leaving them at increased risk for morbidity and mortality related to vaccine-preventable disease. Without developing and refining approaches to reach and vaccinate children and other vulnerable populations in conflict settings, outbreaks of vaccine-preventable disease in these settings may persist and spread across subnational and international borders. Understanding and refining current approaches to vaccinating populations in conflict and humanitarian emergency settings may save lives. Despite major setbacks, the Global Polio Eradication Initiative has made substantial progress in vaccinating millions of children worldwide, including those living in communities affected by conflicts and other humanitarian emergencies. In this article, we examine key strategic and operational tactics that have led to increased polio vaccination coverage among populations living in diverse conflict settings, including Nigeria, Somalia, and Pakistan, and how these could be applied to reach and vaccinate populations in other settings across the world.

In September 2015, more than 1 year after reporting its last wild poliovirus (WPV) case in July 2014 (1), Nigeria was removed from the list of countries with endemic poliovirus transmission,* leaving Afghanistan and Pakistan as the only remaining countries with endemic WPV. However, on April 29, 2016, a laboratory-confirmed, circulating vaccine-derived poliovirus type 2 (cVDPV2) isolate was reported from an environmental sample collected in March from a sewage effluent site in Maiduguri Municipal Council, Borno State, a security-compromised area in northeastern Nigeria. VDPVs are genetic variants of the vaccine viruses with the potential to cause paralysis and can circulate in areas with low population immunity. The Nigeria National Polio Emergency Operations Center initiated emergency response activities, including administration of at least 2 doses of oral poliovirus vaccine (OPV) to all children aged <5 years through mass campaigns; retroactive searches for missed cases of acute flaccid paralysis (AFP), and enhanced environmental surveillance. Approximately 1 million children were vaccinated in the first OPV round. Thirteen previously unreported AFP cases were identified. Enhanced environmental surveillance has not resulted in detection of additional VDPV isolates. The detection of persistent circulation of VDPV2 in Borno State highlights the low population immunity, surveillance limitations, and risk for international spread of cVDPVs associated with insurgency-related insecurity. Increasing vaccination coverage with additional targeted supplemental immunization activities and reestablishment of effective routine immunization activities in newly secured and difficult-to-reach areas in Borno is urgently needed.

Introduction. Nigeria is among the 3 countries in which polio remains endemic. The country made significant efforts to reduce polio transmission but remains challenged by poor-quality campaigns and poor team performance in some areas. This article demonstrates the application of geographic information system technology to track vaccination teams to monitor settlement coverage, reduce the number of missed settlements, and improve team performance.Methods. In each local government area where tracking was conducted, global positioning system–enabled Android phones were given to each team on a daily basis and were used to record team tracks. These tracks were uploaded to a dashboard to show the level of coverage and identify areas missed by the teams.Results. From 2012 to June 2015, tracking covered 119 immunization days. A total of 1149 tracking activities were conducted. Of these, 681 (59%) were implemented in Kano state. There was an improvement in the geographic coverage of settlements and an overall reduction in the number of missed settlements.Conclusions. The tracking of vaccination teams provided significant feedback during polio campaigns and enabled supervisors to evaluate performance of vaccination teams. The reports supported other polio program activities, such as review of microplans and the deployment of other interventions, for increasing population immunity in northern Nigeria.

Efforts to interrupt transmission remain impeded by poor SIA implementation in localized areas, anti-polio vaccine sentiment, and limited access to vaccinate children because of insecurity. Sustained improvement in SIA quality, surveillance, and outbreak response and special strategies in security-compromised areas are needed to interrupt WPV transmission in 2014.

Introduction. Poliomyelitis remains a global threat despite availability of oral polio vaccine (OPV), proven to reduce the burden of the paralyzing disease. In Nigeria, children continue to miss the opportunity to be fully vaccinated, owing to factors such as unmet health needs and low uptake in security-compromised and underserved communities. We describe the implementation and evaluation of several activities to create demand for polio vaccination in persistently poor-performing local government areas (LGAs).Methods. We assessed the impact of various polio-related interventions, to measure the contribution of demand creation activities in 77 LGAs at very high risk for polio, located across 10 states in northern Nigeria. Interventions included provision of commodities along with the polio vaccine.Results. There was an increasing trend in the number of children reached by different demand creation interventions. A total of 4 819 847 children were vaccinated at health camps alone. There was a reduction in the number of wards in which >10% of children were missed by supplementary immunization activities due to noncompliance with vaccination recommendations, a rise in the proportion of children who received ≥4 OPV doses, and a decrease in the proportion of children who were underimmunized or unimmunized.Conclusions. Demand creation interventions increased the uptake of polio vaccines in persistently poor-performing high-risk communities in northern Nigeria during September 2013–November 2014.

Background. Cases of paralysis caused by poliovirus have decreased by >99% since the 1988 World Health Assembly's resolution to eradicate polio. The World Health Organization identified environmental surveillance (ES) of poliovirus in the poliomyelitis eradication strategic plan as an activity that can complement acute flaccid paralysis (AFP) surveillance. This article summarizes key public health interventions that followed the isolation of polioviruses from ES between 2012 and 2015.Methods. The grap method was used to collect 1.75 L of raw flowing sewage every 2–4 weeks. Once collected, samples were shipped at 4°C to a polio laboratory for concentration. ES data were then used to guide program implementation.Results. From 2012 to 2015, ES reported 97 circulating vaccine-derived polioviruses (cVDPV2) and 14 wild polioviruses. In 2014 alone, 54 cVDPV type 2 cases and 1 WPV type 1 case were reported. In Sokoto State, 58 cases of AFP were found from a search of 9426 households. A total of 2 252 059 inactivated polio vaccine and 2 460 124 oral polio vaccine doses were administered to children aged <5 year in Borno and Yobe states.Conclusions. This article is among the first from Africa that relates ES findings to key public health interventions (mass immunization campaigns, inactivated polio vaccine introduction, and strengthening of AFP surveillance) that have contributed to the interruption of poliovirus transmission in Nigeria.

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BackgroundGlobal withdrawal of serotype-2 oral poliovirus vaccine (OPV2) took place in April 2016. This marked a milestone in global polio eradication and was a public health intervention of unprecedented scale, affecting 155 countries. Achieving high levels of serotype-2 population immunity before OPV2 withdrawal was critical to avoid subsequent outbreaks of serotype-2 vaccine-derived polioviruses (VDPV2s).Methods and FindingsIn August 2015, we estimated vaccine-induced population immunity against serotype-2 poliomyelitis for 1 January 2004–30 June 2015 and produced forecasts for April 2016 by district in Nigeria and Pakistan. Population immunity was estimated from the vaccination histories of children <36 mo old identified with non-polio acute flaccid paralysis (AFP) reported through polio surveillance, information on immunisation activities with different oral poliovirus vaccine (OPV) formulations, and serotype-specific estimates of the efficacy of these OPVs against poliomyelitis. District immunity estimates were spatio-temporally smoothed using a Bayesian hierarchical framework. Coverage estimates for immunisation activities were also obtained, allowing for heterogeneity within and among districts. Forward projections of immunity, based on these estimates and planned immunisation activities, were produced through to April 2016 using a cohort model.Estimated population immunity was negatively correlated with the probability of VDPV2 poliomyelitis being reported in a district. In Nigeria and Pakistan, declines in immunity during 2008–2009 and 2012–2013, respectively, were associated with outbreaks of VDPV2. Immunity has since improved in both countries as a result of increased use of trivalent OPV, and projections generally indicated sustained or improved immunity in April 2016, such that the majority of districts (99% [95% uncertainty interval 97%–100%] in Nigeria and 84% [95% uncertainty interval 77%–91%] in Pakistan) had >70% population immunity among children <36 mo old. Districts with lower immunity were clustered in northeastern Nigeria and northwestern Pakistan. The accuracy of immunity estimates was limited by the small numbers of non-polio AFP cases in some districts, which was reflected by large uncertainty intervals. Forecasted improvements in immunity for April 2016 were robust to the uncertainty in estimates of baseline immunity (January–June 2015), vaccine coverage, and vaccine efficacy.ConclusionsImmunity against serotype-2 poliomyelitis was forecasted to improve in April 2016 compared to the first half of 2015 in Nigeria and Pakistan. These analyses informed the endorsement of OPV2 withdrawal in April 2016 by the WHO Strategic Advisory Group of Experts on Immunization.