Li Ka Shing Centre for Healthcare Analytics Research and Training, St. Michael's Hospital, Toronto, ON M5B1W8, Canada;
Eliot Phillipson Clinician-Scientist Training Program, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada.
Proc Natl Acad Sci U S A. 2018 Feb 13;115(7):1593-1598. doi: 10.1073/pnas.1711923115. Epub 2018 Jan 29.
Pakistan is one of three countries in which endemic transmission of poliovirus has never been stopped. Insecurity is often cited but poorly studied as a barrier to eradicating polio. We analyzed routinely collected health data from 32 districts of northwest Pakistan and constructed an index of insecurity based on journalistic reports of the monthly number of deaths and injuries resulting from conflict-related security incidents. The primary outcomes were the monthly incidence of paralytic polio cases within each district between 2007 and 2014 and the polio vaccination percentage from 666 district-level vaccination campaigns between 2007 and 2009, targeting ∼5.7 million children. Multilevel Poisson regression controlling for time and district fixed effects was used to model the association between insecurity, vaccinator access, vaccination rates, and polio incidence. The number of children inaccessible to vaccinators was 19.7% greater (95% CI: 19.2-20.2%), and vaccination rates were 5.3% lower (95% CI: 5.2-5.3%) in "high-insecurity" campaigns compared with "secure" campaigns. The unadjusted mean vaccination rate was 96.3% (SD = 8.6) in secure campaigns and 88.3% (SD = 19.2) in high-insecurity campaigns. Polio incidence was 73.0% greater (95% CI: 30-131%) during high-insecurity months (unadjusted mean = 0.13 cases per million people, SD = 0.71) compared with secure months (unadjusted mean = 1.23 cases per million people, SD = 4.28). Thus, insecurity was associated with reduced vaccinator access, reduced polio vaccination, and increased polio incidence in northwest Pakistan. These findings demonstrate that insecurity is an important obstacle to global polio eradication.
巴基斯坦是三个从未停止过脊髓灰质炎病毒地方性传播的国家之一。不安全因素经常被提及，但作为消除脊灰炎的障碍，其研究却很少。我们分析了来自巴基斯坦西北部 32 个地区的常规收集的卫生数据，并根据新闻报道的每月因与冲突有关的安全事件而导致的死亡和受伤人数，构建了一个不安全指数。主要结果是 2007 年至 2014 年期间每个地区每月麻痹性脊灰炎病例的发病率，以及 2007 年至 2009 年 666 次地区级疫苗接种运动的脊灰炎疫苗接种率，目标人群为约 570 万儿童。使用多水平泊松回归控制时间和地区固定效应，对不安全因素、疫苗接种人员的可及性、疫苗接种率和脊灰炎发病率之间的关系进行建模。在“高不安全”疫苗接种运动中，无法接触到疫苗接种人员的儿童人数增加了 19.7%（95%CI：19.2-20.2%），疫苗接种率降低了 5.3%（95%CI：5.2-5.3%）。在“安全”疫苗接种运动中，未调整的平均疫苗接种率为 96.3%（SD=8.6），在“高不安全”疫苗接种运动中为 88.3%（SD=19.2）。脊灰炎发病率在“高不安全”月份增加了 73.0%（95%CI：30-131%）（未调整的平均发病率为每百万人 0.13 例，SD=0.71），与“安全”月份（未调整的平均发病率为每百万人 1.23 例，SD=4.28）相比。因此，在巴基斯坦西北部，不安全因素与疫苗接种人员可及性降低、脊灰炎疫苗接种减少和脊灰炎发病率增加有关。这些发现表明，不安全因素是全球消灭脊灰炎的一个重要障碍。
