Data from: Global yellow fever vaccination coverage from 1970 to 2016: an adjusted retrospective analysis

Background: Substantial outbreaks of yellow fever in Angola and Brazil in the past 2 years, combined with global shortages in vaccine stockpiles, highlight a pressing need to assess present control strategies. The aims of this study were to estimate global yellow fever vaccination coverage from 1970 through to 2016 at high spatial resolution and to calculate the number of individuals still requiring vaccination to reach population coverage thresholds for outbreak prevention. Methods: For this adjusted retrospective analysis, we compiled data from a range of sources (eg, WHO reports and health-service-provider registeries) reporting on yellow fever vaccination activities between May 1, 1939, and Oct 29, 2016. To account for uncertainty in how vaccine campaigns were targeted, we calculated three population coverage values to encompass alternative scenarios. We combined these data with demographic information and tracked vaccination coverage through time to estimate the proportion of the population who had ever received a yellow fever vaccine for each second level administrative division across countries at risk of yellow fever virus transmission from 1970 to 2016. Findings: Overall, substantial increases in vaccine coverage have occurred since 1970, but notable gaps still exist in contemporary coverage within yellow fever risk zones. We estimate that between 393·7 million and 472·9 million people still require vaccination in areas at risk of yellow fever virus transmission to achieve the 80% population coverage threshold recommended by WHO; this represents between 43% and 52% of the population within yellow fever risk zones, compared with between 66% and 76% of the population who would have required vaccination in 1970. Interpretation: Our results highlight important gaps in yellow fever vaccination coverage, can contribute to improved quantification of outbreak risk, and help to guide planning of future vaccination efforts and emergency stockpiling.背景：过去两年安哥拉与巴西暴发大规模黄热病（yellow fever）疫情，叠加全球疫苗储备短缺问题，凸显了评估现有防控策略的迫切需求。本研究旨在以高空间分辨率估算1970年至2016年的全球黄热病疫苗接种覆盖率，并计算仍需接种疫苗的人群数量，以达到防控疫情暴发的人群接种阈值。方法：本项调整型回顾性分析整合了1939年5月1日至2016年10月29日期间，多来源的黄热病疫苗接种活动数据（如世界卫生组织（World Health Organization, WHO）报告、卫生服务提供者登记系统）。为考量疫苗接种运动的目标设定不确定性，我们计算了三类人群接种覆盖率以覆盖多种备选场景。我们将这些数据与人口统计信息相结合，追踪不同时段的疫苗接种覆盖率，以估算1970年至2016年间，黄热病病毒传播风险国家内各二级行政区划（second-level administrative division）中，曾接种过黄热病疫苗的人群比例。结果：总体而言，自1970年以来疫苗覆盖率已实现显著提升，但当前黄热病风险区域内的接种覆盖率仍存在显著缺口。我们估算，在黄热病病毒传播风险区域内，仍有3.937亿至4.729亿人口需接种疫苗，才能达到世界卫生组织推荐的80%人群接种阈值；该人群占黄热病风险区域总人口的43%至52%，而1970年时这一需接种人群占比为66%至76%。解读：本研究结果凸显了黄热病疫苗接种覆盖率存在的重要缺口，可为疫情暴发风险的量化优化提供支撑，并有助于指导未来疫苗接种工作规划与应急疫苗储备。