Polio Elimination Branch, US Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
African Field Epidemiology Network, Ebonyi State, Nigeria.
Pan Afr Med J. 2023 Jul 14;45(Suppl 2):7. doi: 10.11604/pamj.supp.2023.45.2.39332. eCollection 2023.
ultimately detected in 2016, wild poliovirus (WPV) transmission continued undetected after 2011 in Northeast Nigeria Borno and Yobe States in security-compromised areas, inaccessible due to armed insurgency. Varying inaccessibility prevented children aged <5 years in these areas from polio vaccination interventions and surveillance, while massive population displacements occurred. We examined progress in access over time to provide data supporting a very low probability of undetected WPV circulation within remaining trapped populations after 2016.
to assess the extent of inaccessibility in security-compromised areas, we obtained empirical historical data in 2020 on a quarterly and annual basis from relevant polio eradication staff for the period 2010-2020. The extent of access to areas for immunization by recall was compared to geospatial data from vaccinator tracking. Population estimates over time in security-compromised areas were extracted from satellite imagery. We compared the historical access data from staff with tracking and population esimates.
access varied during 2010-2020, with inaccessibility peaking during 2014-2016. We observed concurrent patterns between historical recalled data on inaccessibility and contemporaneous satellite imagery on population displacements, which increased confidence in the quality of recalled data.
staff-recalled access was consistent with vaccinator tracking and satellite imagery of population displacments. Despite variability in inaccessibility over time, innovative immunization initiatives were implemented as access allowed and surveillance initiatives were initiated to search for poliovirus transmission. Along with escape and liberation of residents by the military in some geographic areas, these initiatives resulted in a massive reduction in the size of the unvaccinated population remaining resident.
野脊髓灰质炎病毒（WPV）于 2016 年最终被发现，在 2011 年后，尼日利亚东北部博尔诺州和约贝州的安全局势受到影响的地区仍持续存在 WPV 传播，但未被发现，这些地区因武装叛乱而无法进入。由于进入这些地区存在不同程度的困难，导致 5 岁以下儿童无法接受脊灰疫苗接种干预和监测，同时也发生了大规模的人口流离失所。我们研究了随着时间的推移，进入这些地区的进展情况，以提供数据支持 2016 年后，在剩余的受困人群中，未被发现的 WPV 传播的可能性非常低。
为了评估安全局势受到影响地区的可达性程度，我们在 2020 年从相关脊灰根除工作人员那里获得了 2010-2020 年期间按季度和年度划分的经验历史数据。通过回忆法评估免疫接种区域的可达性程度，并与疫苗接种员跟踪的地理空间数据进行比较。从卫星图像中提取安全局势受到影响地区的人口估计数据。我们将工作人员的历史访问数据与跟踪和人口估计数据进行了比较。
2010-2020 年期间，进入这些地区的情况各不相同，在 2014-2016 年期间，可达性最低。我们观察到，关于可达性的历史回忆数据与关于人口流离失所的同期卫星图像之间存在同步模式，这增加了回忆数据质量的可信度。
工作人员回忆的可达性与疫苗接种员的跟踪和人口流离失所的卫星图像一致。尽管可达性随时间而变化，但随着进入的机会增加，创新性的免疫接种举措得以实施，并启动了监测举措以寻找脊灰病毒的传播。随着军事在一些地理区域内的居民的逃脱和解放，这些举措使得未接种疫苗的剩余居民人数大幅减少。
